Materiały źródłowe

• #1 Pneumonia Pathology – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526116/

  Pneumonia is an umbrella term for a group of syndromes caused by a variety of organisms that result in infection of the lung parenchyma. […] Pneumonia has been defined as an infection of the lung parenchyma. Rather than looking at it as a single disease, health care professionals must remember that pneumonia is an umbrella term for a group of syndromes caused by a variety of organisms resulting in varied manifestations and sequelae. […] These categories have helped establish the common organisms responsible for each type of pneumonia and helped to formulate treatment guidelines for the efficient management in both in-patient and out-patient setting. […] There is an intricate balance between the organisms residing in the lower respiratory tract and the local and systemic defense mechanisms (both innate and acquired) which when disturbed gives rise to inflammation of the lung parenchyma, i.e., pneumonia. Common defense mechanisms that are compromised in the pathogenesis of pneumonia include:

• #2 Pneumonia – Wikipedia

  https://en.wikipedia.org/wiki/Pneumonia

  Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms. […] Pneumonia frequently starts as an upper respiratory tract infection that moves into the lower respiratory tract. It is a type of pneumonitis (lung inflammation). […] The progress of pneumonia is determined by the virulence of the organism; the amount of organism required to start an infection; and the body’s immune response against the infection. […] Most bacteria enter the lungs via small aspirations of organisms residing in the throat or nose. […] Once in the lungs, bacteria may invade the spaces between cells and between alveoli, where the macrophages and neutrophils (defensive white blood cells) attempt to inactivate the bacteria. […] The invasion of the lungs may lead to varying degrees of cell death. […] Pneumonia can cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response.

• #3 Learn About Pneumonia | American Lung Association

  https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia/learn-about-pneumonia

  Pneumonia is an infection of the lungs that may be caused by bacteria, viruses, or fungi. The infection causes the lungs’ air sacs (alveoli) to become inflamed and fill up with fluid or pus. That can make it hard for the oxygen you breathe in to get into your bloodstream. […] Many factors affect how serious a case of pneumonia is, such as the type of germ causing the lung infection, the persons age, and their overall health. […] Pneumonia can be caused by a wide variety of bacteria, viruses and fungi in the air we breathe. Identifying the cause of your pneumonia can be an important step in getting the proper treatment. […] People age 65 and over are at increased risk because their immune system is becoming less able to fight off infection as years go by. Infants and children two years of age or younger are also at increased risk because their immune systems are not yet fully developed.

• #4 Pneumonia: Causes, Symptoms, Diagnosis & Treatment

  https://my.clevelandclinic.org/health/diseases/4471-pneumonia

  Pneumonia is inflammation and fluid in your lungs caused by a bacterial, viral or fungal infection. Pneumonia causes your lung tissue to swell (inflammation) and can cause fluid or pus in your lungs. Bacterial pneumonia is usually more severe than viral pneumonia, which often resolves on its own. […] Pneumonia can develop when your immune system attacks an infection in the small sacs of your lung (alveoli). This causes your lungs to swell and leak fluids. […] Many bacteria, viruses and fungi can cause the infections that lead to pneumonia. Bacteria are the most common cause in adults and viruses are the most common cause in school-aged children. […] Pneumonia can lead to serious complications that can require hospitalization, including breathing difficulties. Pneumonia can lead to respiratory failure or acute respiratory distress syndrome (ARDS). […] If you have a severe case of pneumonia or complications, you may need to stay in the hospital for treatment.

• #5 Pneumonia – Wikipedia

  https://en.wikipedia.org/wiki/Pneumonia

  Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms. […] Pneumonia frequently starts as an upper respiratory tract infection that moves into the lower respiratory tract. It is a type of pneumonitis (lung inflammation). […] The progress of pneumonia is determined by the virulence of the organism; the amount of organism required to start an infection; and the body’s immune response against the infection. […] Most bacteria enter the lungs via small aspirations of organisms residing in the throat or nose. […] Once in the lungs, bacteria may invade the spaces between cells and between alveoli, where the macrophages and neutrophils (defensive white blood cells) attempt to inactivate the bacteria. […] The invasion of the lungs may lead to varying degrees of cell death. […] Pneumonia can cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response.

• #6 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  Pneumonia is an acute respiratory infection of the lung parenchyma caused by one or co-infecting pathogens. These pathogens cause the lung parenchyma (alveoli) to become inflamed and fill with pus and fluid, limiting oxygen intake and making gas exchange ineffective. […] In Pneumonia, however, this screening mechanism would have been damaged by previous or ongoing illnesses and harmful pathogens manage to find their way into the lower respiratory tract. […] In addition, pathogens can also enter the lungs through the circulatory system. Bloodborne pathogens can travel through the body until they reach the pulmonary circulation. There they enter the pulmonary capillary bed and settle at the bottom of the lungs. […] Once the pathogens are stuck, some of the alveoli become inflamed and they fill up with a thick exudate that interferes with the exchange of oxygen and carbon dioxide. Naturally, the body has to fight this off so it sends Neutrophils into the alveoli, but in doing it fills the last few empty spaces of air in the alveoli. Following that, the mucosa starts to swell up causing mucosal oedema and partially occluding the bronchi, and in some cases, if the patient has other respiratory conditions bronchospasm would occur.

• #7 Pneumonia – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/pneumonia/symptoms-causes/syc-20354204

  Most pneumonia occurs when a breakdown in your body’s natural defenses allows germs to invade and multiply within your lungs. […] Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. […] Pneumonia can range in seriousness from mild to life-threatening. […] Many germs can cause pneumonia. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good. […] Pneumonia is classified according to the types of germs that cause it and where you got the infection. […] Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals or other health care facilities.

• #8 Pathogenesis, Diagnosis and Therapeutic Strategies for Ventilator-associated Pneumonia – Journal of Pure and Applied Microbiology

  https://microbiologyjournal.org/pathogenesis-diagnosis-and-therapeutic-strategies-for-ventilator-associated-pneumonia/

  Ventilator-associated pneumonia (VAP) is a major health care associated infection which usually emanates from aspiration, immigration of pathogens from aerodigestive tract, adulterated appliance uses or medications. […] The ICU admitted patients who are ventilated, have several reasons like critical illness, comorbidities, and malnutrition that affect their immune system. […] Endotracheal intubations suppress the cough impulse, hamper muco-ciliary clearance, damage the tracheal epithelial surface and make a path for pathogenic bacteria which migrate from upper respiratory tract to lower respiratory tract. […] These pathogens then adhere to the mucosa of lower respiratory tract of mechanically ventilated patients and start infections. […] Generally, four routes are responsible for providing access to microorganisms in order to produce VAP infections a) Aspiration from oropharynx or from stomach into oropharynx then into the lower respiratory tract, b) Extension of contiguous infection, c) Contaminated air or ICU aerosol inhalation, and d) Vascular or urinary catheter-related blood-stream infection seeding the lungs.

• #9 Learn About Pneumonia | American Lung Association

  https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia/learn-about-pneumonia

  Chronic lung diseases such as COPD, bronchiectasis, or cystic fibrosis that make the lungs more vulnerable. […] A weakened immune system due to HIV/AIDs, an organ transplant, chemotherapy or long-term steroid use. […] Difficulty swallowing, due to stroke, dementia, Parkinson’s disease, or other neurological conditions, which can result in aspiration of food, vomit or saliva into the lungs that then becomes infected. […] Recent viral respiratory infectiona cold, laryngitis, influenza, etc. […] Hospitalization, especially when in intensive care and using a ventilator to breathe. […] Cigarette smoking, which damages the lungs. […] Drug and alcohol abuse, which increase the risk of aspiration pneumonia. […] Exposure to certain chemicals, pollutants or toxic fumes, including secondhand smoke.

• #10 Bacterial Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300157-overview

  Bacterial pneumonia is caused by a pathogenic infection of the lungs and may present as a primary disease process or as the final, fatal disorder primarily in an individual who is already debilitated. The causes for the development of pneumonia are extrinsic or intrinsic, and various bacterial causes are noted. Extrinsic factors include exposure to a causative agent, exposure to pulmonary irritants, or direct pulmonary injury. Intrinsic factors are related to the host. Loss of protective upper airway reflexes allows aspiration of contents from the upper airways into the lung. Various causes for this loss include altered mental status due to intoxication and other metabolic states and neurologic causes, such as stroke and endotracheal intubation. […] Bacteria from the upper airways or, less commonly, from hematogenous spread, find their way to the lung parenchyma. Once there, a combination of factors (including virulence of the infecting organism, status of the local defenses, and overall health of the patient) may lead to bacterial pneumonia. The patient may be made more susceptible to infection because of an overall impairment of the immune response (eg, human immunodeficiency virus [HIV] infection, chronic disease, advanced age) and/or dysfunction of defense mechanisms (eg, smoking, chronic obstructive pulmonary disease [COPD], tumors, inhaled toxins, aspiration).

• #11 adult-pneumonia-pathogenesis-and-clinical-findings | Calgary Guide

  https://calgaryguide.ucalgary.ca/adult-pneumonia-pathogenesis-and-clinical-findings/adult-pneumonia-2022/

  Adult Pneumonia: Pathogenesis and clinical findings […] Smoking suppressed neutrophil function and damaged lung epithelium […] Chronic lung conditions e.g. COPD, asthma, lung cancer destroys lung tissue and offers pathogen more niduses for infection […] Immune suppression e.g. HIV, sepsis, glucocorticoids, chemotherapy suppression of immune response […] Systemic inflammatory response towards invading microbe […] Systemic cytokine release leads to a disruption in hypothalamic thermoregulation […] Exposure to a pathogen via inhalation, aspiration, contiguous Notes: or hematological mechanism […] Susceptible host and/or virulent pathogen […] Proliferation of microbe in lower airways and alveoli […] Local response by alveolar epithelial cells release chemokines into surrounding tissue to recruit neutrophils to the site of inflammation

• #12 Pneumonia Pathology – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526116/

  Pneumonia is an umbrella term for a group of syndromes caused by a variety of organisms that result in infection of the lung parenchyma. […] Pneumonia has been defined as an infection of the lung parenchyma. Rather than looking at it as a single disease, health care professionals must remember that pneumonia is an umbrella term for a group of syndromes caused by a variety of organisms resulting in varied manifestations and sequelae. […] These categories have helped establish the common organisms responsible for each type of pneumonia and helped to formulate treatment guidelines for the efficient management in both in-patient and out-patient setting. […] There is an intricate balance between the organisms residing in the lower respiratory tract and the local and systemic defense mechanisms (both innate and acquired) which when disturbed gives rise to inflammation of the lung parenchyma, i.e., pneumonia. Common defense mechanisms that are compromised in the pathogenesis of pneumonia include:

• #13 Pathogenesis of pneumonia and acute lung injury

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9429452/

  Bacterial pneumonia is categorized Community-acquired and Hospital-acquired pneumonia. […] Bacterial pathogens often have multiple virulence factors that allow them to evade or disrupt host defense mechanisms of the innate immune system. […] In addition to specific virulence factors of bacteria, whether bacteria are present as planktonic single-celled organisms or biofilm bacterial infections will impact the immune response. […] Secondary bacterial infections following a primary viral infection represent a potentially severe complication. […] The pulmonary airway and alveolar spaces have multiple mechanisms to protect the host from infection, and airway-specific factors provide a critical defense against infection. […] While mucus, ASL, and surfactant act as physical barriers that contain potent anti-microbial defense mechanisms, respiratory epithelial cells have a host of receptors located on the cell surface and intracellular compartments that are able to detect pathogen-associated molecular patterns (PAMP) and host-derived danger-associated molecular patterns (DAMP).

• #14 Viral Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300455-overview

  Elderly persons are at increased risk of infection and complications in viral pneumonia because of comorbidities. Waning cellular, humoral, and innate immune functioning may impair viral clearance, which allows spread of the virus to the lower respiratory tract resulting in increased inflammation. […] The mechanism of viral transmission varies with the type of virus. Routes include large-droplet spread over short distances ( 1 m), hand contact with contaminated skin and fomites and subsequent inoculation onto the nasal mucosa or conjunctiva (eg, rhinovirus, RSV), and small-particle aerosol spread (eg, influenza, adenovirus). […] The pulmonary host defense is complex and includes the following components: Mechanical barriers, Humoral immunity, Phagocytic cells, Cell-mediated immunity. […] Cell-mediated immunity is the most important defense mechanism against the intracellular viral pathogens. This immunity is involved in antibody production, cytotoxic activity, and cytokine production. […] A substantial number of peripheral CD8+ memory T cells reside in the lung after a viral infection.

• #15 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  Pneumonia is an acute respiratory infection of the lung parenchyma caused by one or co-infecting pathogens. These pathogens cause the lung parenchyma (alveoli) to become inflamed and fill with pus and fluid, limiting oxygen intake and making gas exchange ineffective. […] In Pneumonia, however, this screening mechanism would have been damaged by previous or ongoing illnesses and harmful pathogens manage to find their way into the lower respiratory tract. […] In addition, pathogens can also enter the lungs through the circulatory system. Bloodborne pathogens can travel through the body until they reach the pulmonary circulation. There they enter the pulmonary capillary bed and settle at the bottom of the lungs. […] Once the pathogens are stuck, some of the alveoli become inflamed and they fill up with a thick exudate that interferes with the exchange of oxygen and carbon dioxide. Naturally, the body has to fight this off so it sends Neutrophils into the alveoli, but in doing it fills the last few empty spaces of air in the alveoli. Following that, the mucosa starts to swell up causing mucosal oedema and partially occluding the bronchi, and in some cases, if the patient has other respiratory conditions bronchospasm would occur.

• #16 Pathophysiology of Pneumonia – Pathology

  https://pressbooks.bccampus.ca/pathology/chapter/pathophysiology-of-pulmonary-edema/

  Pneumonia is an infection of one or both lungs that is characterized by inflammation of the alveoli and interstitial tissue. […] Pneumonia is largely considered to be the result of failure in the host response to pathogens, although the individual properties of microorganisms do contribute to their ability to cause pneumonia. […] Failure of pulmonary protective mechanisms, in addition to features of the pathogen that help it infect the airways, can lead to penetration and proliferation of the pathogen in the lower respiratory tract. […] The bodys response to infection is what causes the clinical and histopathological findings of pneumonia, which will be discussed in more detail in later chapters. […] Infection and tissue damage spurs a systemic inflammatory response when chemical messengers called cytokines are released, although the exact inflammatory response depends on the type of pathogen.

• #17 Pneumonia Pathology – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526116/

  The resident macrophages serve to protect the lung from foreign pathogens. Ironically, the inflammatory reaction triggered by these very macrophages is what is responsible for the histopathological and clinical findings seen in pneumonia. The macrophages engulf these pathogens and trigger signal molecules or cytokines like TNF-a, IL-8, and IL-1 that recruit inflammatory cells like neutrophils to the site of infection. They also serve to present these antigens to the T cells that trigger both cellular and humoral defense mechanisms, activate complement and form antibodies against these organisms. This, in turn, causes inflammation of the lung parenchyma and makes the lining capillaries „leaky,” which leads to exudative congestion and underlines the pathogenesis of pneumonia.

• #18 Pneumonia Pathology – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526116/

  The resident macrophages serve to protect the lung from foreign pathogens. Ironically, the inflammatory reaction triggered by these very macrophages is what is responsible for the histopathological and clinical findings seen in pneumonia. The macrophages engulf these pathogens and trigger signal molecules or cytokines like TNF-a, IL-8, and IL-1 that recruit inflammatory cells like neutrophils to the site of infection. They also serve to present these antigens to the T cells that trigger both cellular and humoral defense mechanisms, activate complement and form antibodies against these organisms. This, in turn, causes inflammation of the lung parenchyma and makes the lining capillaries „leaky,” which leads to exudative congestion and underlines the pathogenesis of pneumonia.

• #19 Bacterial Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300157-overview

  During pulmonary infection, acute inflammation results in the migration of neutrophils out of capillaries and into the air spaces, forming a marginated pool of neutrophils that is ready to respond when needed. These neutrophils phagocytize microbes and kill them with reactive oxygen species, antimicrobial proteins, and degradative enzymes. […] General mechanisms of increased virulence include the following: Genetic flexibility allowing the development of resistance to various classes of antibiotics; Flagellae and other bacterial appendages that facilitate spread of infection; Capsules resistant to attack by immune defense cells and that facilitate adhesion to host cells; Quorum sensing systems allow coordination of gene expression based on complex cell-signaling for adaptation to the local cellular environment; Iron scavenging.

• #20 Pathophysiology of Pneumonia – Pathology

  https://pressbooks.bccampus.ca/pathology/chapter/pathophysiology-of-pulmonary-edema/

  The inflammatory response aims to destroy invading pathogens and infected cells, but also causes damage to the healthy lung tissue. […] The pattern of inflammation can vary depending on the invading pathogen, but all may lead to the characteristic symptoms of fever/chills, fatigue, and dyspnea. […] Gas exchange can be impaired in pneumonia by the accumulation of fluid in the alveoli (pulmonary edema) or by the thickening of the space between alveoli and capillaries. […] Pneumonia instead may cause pulmonary edema through inflammatory mechanisms by increasing the permeability of blood vessels in response to infection and tissue damage in the lungs, causing fluid to leak into the lungs. […] The inflammatory response in the alveolar walls cause irritation and also trigger the cough reflex.

• #21 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  Pneumonia is an acute respiratory infection of the lung parenchyma caused by one or co-infecting pathogens. These pathogens cause the lung parenchyma (alveoli) to become inflamed and fill with pus and fluid, limiting oxygen intake and making gas exchange ineffective. […] In Pneumonia, however, this screening mechanism would have been damaged by previous or ongoing illnesses and harmful pathogens manage to find their way into the lower respiratory tract. […] In addition, pathogens can also enter the lungs through the circulatory system. Bloodborne pathogens can travel through the body until they reach the pulmonary circulation. There they enter the pulmonary capillary bed and settle at the bottom of the lungs. […] Once the pathogens are stuck, some of the alveoli become inflamed and they fill up with a thick exudate that interferes with the exchange of oxygen and carbon dioxide. Naturally, the body has to fight this off so it sends Neutrophils into the alveoli, but in doing it fills the last few empty spaces of air in the alveoli. Following that, the mucosa starts to swell up causing mucosal oedema and partially occluding the bronchi, and in some cases, if the patient has other respiratory conditions bronchospasm would occur.

• #22 Journal of Pulmonology and Respiratory Diseases – Molecular Mechanisms and Immune Responses in the Pathogenesis of Pneumonia: Insights into Bacterial and Viral Interactions

  https://www.omicsonline.org/open-access/molecular-mechanisms-and-immune-responses-in-the-pathogenesis-of-pneumonia-insights-into-bacterial-and-viral-interactions-134527.html

  The pathogenesis of pneumonia is multifaceted, involving complex interactions between pathogens and the host’s immune system. Understanding these interactions is crucial for developing effective prevention and treatment strategies. […] Each pathogen employs distinct virulence factors, such as adhesins, toxins, and immune evasion mechanisms, to establish infection and propagate disease. These factors not only facilitate pathogen colonization and replication but also provoke significant immune responses that can lead to tissue damage and exacerbation of clinical symptoms. […] The role of the immune response in pneumonia pathogenesis has been characterized by the activation of innate immune cells, such as macrophages and neutrophils, which are essential for pathogen clearance. However, the results indicate that an exaggerated inflammatory response, characterized by elevated levels of pro-inflammatory cytokines such as IL-6 and TNF-, can lead to detrimental effects, including ARDS. […] Dysregulation of this balance contributes to the severity of pneumonia, highlighting the need for targeted therapeutic approaches that modulate immune responses to improve patient outcomes.

• #23 Pathophysiology of Pneumonia – Pathology

  https://pressbooks.bccampus.ca/pathology/chapter/pathophysiology-of-pulmonary-edema/

  The inflammatory response aims to destroy invading pathogens and infected cells, but also causes damage to the healthy lung tissue. […] The pattern of inflammation can vary depending on the invading pathogen, but all may lead to the characteristic symptoms of fever/chills, fatigue, and dyspnea. […] Gas exchange can be impaired in pneumonia by the accumulation of fluid in the alveoli (pulmonary edema) or by the thickening of the space between alveoli and capillaries. […] Pneumonia instead may cause pulmonary edema through inflammatory mechanisms by increasing the permeability of blood vessels in response to infection and tissue damage in the lungs, causing fluid to leak into the lungs. […] The inflammatory response in the alveolar walls cause irritation and also trigger the cough reflex.

• #24 Pneumonia | PPT

  https://www.slideshare.net/slideshow/pneumonia-61496183/61496183

  Pneumonia is an infection in one or both lungs. Pneumonia causes inflammation in the alveoli. The alveoli are filled with fluid or pus, making it difficult to breathe. […] Most of the time, the body filters organisms. This keeps the lungs from becoming infected. But organisms sometimes enter the lungs and cause infections. This is more likely to occur when: immune system is weak. organism is very strong. body fails to filter the organisms. […] PATHOLOGY Congestion Presence of a proteinaceous exudate and often of bacteria in the alveoli. […] RED HEPATIZATION Presence of erythrocytes in the cellular intraalveolar exudate Neutrophils are also present Bacteria are occasionally seen in cultures of alveolar specimens collected. […] GRAY HEPATIZATION No new erythrocytes are extravasating, and those already present have been lysed and degraded Neutrophil is the predominant cell Fibrin deposition is abundant Bacteria have disappeared Corresponds with successful containment of the infection and improvement in gas exchange.

• #25 Pneumonia | PPT

  https://www.slideshare.net/slideshow/pneumonia-61496183/61496183

  Pneumonia is an infection in one or both lungs. Pneumonia causes inflammation in the alveoli. The alveoli are filled with fluid or pus, making it difficult to breathe. […] Most of the time, the body filters organisms. This keeps the lungs from becoming infected. But organisms sometimes enter the lungs and cause infections. This is more likely to occur when: immune system is weak. organism is very strong. body fails to filter the organisms. […] PATHOLOGY Congestion Presence of a proteinaceous exudate and often of bacteria in the alveoli. […] RED HEPATIZATION Presence of erythrocytes in the cellular intraalveolar exudate Neutrophils are also present Bacteria are occasionally seen in cultures of alveolar specimens collected. […] GRAY HEPATIZATION No new erythrocytes are extravasating, and those already present have been lysed and degraded Neutrophil is the predominant cell Fibrin deposition is abundant Bacteria have disappeared Corresponds with successful containment of the infection and improvement in gas exchange.

• #26 Pneumonia | PPT

  https://www.slideshare.net/slideshow/pneumonia-61496183/61496183

  RESOLUTION Macrophage is the dominant cell type in the alveolar space Debris of neutrophils, bacteria, and fibrin has been cleared. […] Pneumonia is an inflammatory lung condition caused by bacteria or viruses that enter the lungs. When pathogens enter the alveoli, or air sacs, white blood cells rush to fight the infection, filling the sacs with fluid and pus. […] Pneumonia is an infection that causes inflammation in the lungs. There are two main types: lobar pneumonia, which affects one lung lobe, and bronchopneumonia, which causes patches throughout both lungs. Pneumonia is usually caused by bacteria or viruses and risks factors include age, smoking, and pre-existing medical conditions. […] Pneumonia is an inflammation of the lung parenchyma caused by a microbial agent. It can be caused by bacteria, viruses, fungi or parasites.

• #27 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  All of these factors limit the oxygen intake into the affected lung and create an imbalance in the Ventilation-Perfusion Ratio. Since the lungs do not have enough oxygen in them, they cannot fully oxygenate the venous blood entering the pulmonary circulation. The poorly oxygenated blood will then enter the left side of the heart and be pumped around the body. But because it has very little oxygen to distribute Arterial Hypoxemia develops. […] This problem can occur in different areas of the lungs, depending on where the pathogens settle. If it attacks a large portion of one or more lobes it is referred to as Lobular Pneumonia. But if it attacks many different patches along the bronchi and stretches out to the nearest parenchyma it is called Bronchopneumonia.

• #28 adult-pneumonia-pathogenesis-and-clinical-findings | Calgary Guide

  https://calgaryguide.ucalgary.ca/adult-pneumonia-pathogenesis-and-clinical-findings/adult-pneumonia-2022/

  Pathogens can be bacteria, viruses, fungi and parasites […] Pneumonia is a lower respiratory tract infection (in contrast to upper respiratory tract infections such as bronchitis) and can be further classified by location of exposure: community, health-care, hospital acquired […] Inflammatory response varies depending on type of invading pathogen (i.e. S. Pneumonia causes a lobar pattern and Influenza A B cause an interstitial pattern) […] LOBAR: Accumulation of neutrophils and plasma exudate from capillaries into alveoli specific to a lung area/lobe […] INTERSTITIAL: Accumulation of infiltrates (i.e. inflamed cellular debris) in the alveolar walls (i.e. space between the alveolar spaces and bloodstream) […] Irritation and attempted clearance of airways […] Fluid infiltrates are inside alveoli, airway clearance leads to phlegm production

• #29 Lobar pneumonia – Wikipedia

  https://en.wikipedia.org/wiki/Lobar_pneumonia

  Lobar pneumonia is a form of pneumonia characterized by inflammatory exudate within the intra-alveolar space resulting in consolidation that affects a large and continuous area of the lobe of a lung. […] The invading organism starts multiplying, thereby releasing toxins that cause inflammation and edema of the lung parenchyma. This leads to the accumulation of cellular debris within the lungs. This leads to consolidation or solidification, terms used for macroscopic or radiologic appearance of the lungs affected by pneumonia. Bacterial pneumonia is mainly classified into lobar and diffuse depending on the degree of lung irritation or damage. […] Identifying the infectious organism (or other cause) is an important part of modern treatment of pneumonia. The anatomical patterns of distribution can be associated with certain organisms, and can help in selection of an antibiotic while waiting for the pathogen to be cultured.

• #30 The Radiology Assistant : Chest X-Ray – Lung disease

  https://radiologyassistant.nl/chest/chest-x-ray/lung-disease

  Consolidation is the result of replacement of air in the alveoli by transudate, pus, blood, cells or other substances. Pneumonia is by far the most common cause of consolidation. The disease usually starts within the alveoli and spreads from one alveolus to another. When it reaches a fissure the spread stops there. […] The key-findings on the X-ray are: ill-defined homogeneous opacity obscuring vessels, Silhouette sign: loss of lung/soft tissue interface, Air-bronchogram, Extention to the pleura or fissure, but not crossing it, No volume loss. […] A way to think of the differential diagnosis is to think of the possible content of the alveoli: Water – transudate, Pus – exsudate, Blood – hemorrhage, Cells – tumor, chronic inflammation. […] Now it is obvious that some diseases can have more than one pattern. For instance a lobar pneumonia caused by streptococcus pneumoniae may become diffuse if the patient does not respond to the treatment. Other examples are organizing pneumonia (OP) and chronic eosinophilic pneumonia. These diseases typically present as multifocal consolidations, but sometimes they may become diffuse.

• #31 adult-pneumonia-pathogenesis-and-clinical-findings | Calgary Guide

  https://calgaryguide.ucalgary.ca/adult-pneumonia-pathogenesis-and-clinical-findings/adult-pneumonia-2022/

  Pathogens can be bacteria, viruses, fungi and parasites […] Pneumonia is a lower respiratory tract infection (in contrast to upper respiratory tract infections such as bronchitis) and can be further classified by location of exposure: community, health-care, hospital acquired […] Inflammatory response varies depending on type of invading pathogen (i.e. S. Pneumonia causes a lobar pattern and Influenza A B cause an interstitial pattern) […] LOBAR: Accumulation of neutrophils and plasma exudate from capillaries into alveoli specific to a lung area/lobe […] INTERSTITIAL: Accumulation of infiltrates (i.e. inflamed cellular debris) in the alveolar walls (i.e. space between the alveolar spaces and bloodstream) […] Irritation and attempted clearance of airways […] Fluid infiltrates are inside alveoli, airway clearance leads to phlegm production

• #32 The Radiology Assistant : Chest X-Ray – Lung disease

  https://radiologyassistant.nl/chest/chest-x-ray/lung-disease

  Consolidation is the result of replacement of air in the alveoli by transudate, pus, blood, cells or other substances. Pneumonia is by far the most common cause of consolidation. The disease usually starts within the alveoli and spreads from one alveolus to another. When it reaches a fissure the spread stops there. […] The key-findings on the X-ray are: ill-defined homogeneous opacity obscuring vessels, Silhouette sign: loss of lung/soft tissue interface, Air-bronchogram, Extention to the pleura or fissure, but not crossing it, No volume loss. […] A way to think of the differential diagnosis is to think of the possible content of the alveoli: Water – transudate, Pus – exsudate, Blood – hemorrhage, Cells – tumor, chronic inflammation. […] Now it is obvious that some diseases can have more than one pattern. For instance a lobar pneumonia caused by streptococcus pneumoniae may become diffuse if the patient does not respond to the treatment. Other examples are organizing pneumonia (OP) and chronic eosinophilic pneumonia. These diseases typically present as multifocal consolidations, but sometimes they may become diffuse.

• #33 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  All of these factors limit the oxygen intake into the affected lung and create an imbalance in the Ventilation-Perfusion Ratio. Since the lungs do not have enough oxygen in them, they cannot fully oxygenate the venous blood entering the pulmonary circulation. The poorly oxygenated blood will then enter the left side of the heart and be pumped around the body. But because it has very little oxygen to distribute Arterial Hypoxemia develops. […] This problem can occur in different areas of the lungs, depending on where the pathogens settle. If it attacks a large portion of one or more lobes it is referred to as Lobular Pneumonia. But if it attacks many different patches along the bronchi and stretches out to the nearest parenchyma it is called Bronchopneumonia.

• #34 Pathophysiology of Pneumonia – Pathology

  https://pressbooks.bccampus.ca/pathology/chapter/pathophysiology-of-pulmonary-edema/

  The inflammatory response aims to destroy invading pathogens and infected cells, but also causes damage to the healthy lung tissue. […] The pattern of inflammation can vary depending on the invading pathogen, but all may lead to the characteristic symptoms of fever/chills, fatigue, and dyspnea. […] Gas exchange can be impaired in pneumonia by the accumulation of fluid in the alveoli (pulmonary edema) or by the thickening of the space between alveoli and capillaries. […] Pneumonia instead may cause pulmonary edema through inflammatory mechanisms by increasing the permeability of blood vessels in response to infection and tissue damage in the lungs, causing fluid to leak into the lungs. […] The inflammatory response in the alveolar walls cause irritation and also trigger the cough reflex.

• #35 Pathogenesis of pneumonia and acute lung injury

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9429452/

  Disruption of epithelial and/or endothelial barrier function and disease severity differentiates ALI and ARDS from pneumonia. […] While the host response in pneumonia is contained within the alveolar space, the intact epithelium and alveolar-capillary barrier prevents the flooding of the alveolar space with high molecular weight proteins that characterize the alveolar environment of ARDS. […] This disruption permits the accumulation of proteinaceous fluid in the alveolar space coupled with decreased compliance due to loss of surfactant. […] In the majority of pneumonia cases there is no definitive identification of the causative pathogen. […] While there are now a variety of culture-based and molecular diagnostic tests to aid in pathogen identification, a recent international study reported that the frequency of pathogen detection in adults hospitalized with CAP was only 36.5%.

• #36 Pneumonia Pathophysiology

  https://www.thenursingjournal.com/post/pneumonia-pathophysiology

  All of these factors limit the oxygen intake into the affected lung and create an imbalance in the Ventilation-Perfusion Ratio. Since the lungs do not have enough oxygen in them, they cannot fully oxygenate the venous blood entering the pulmonary circulation. The poorly oxygenated blood will then enter the left side of the heart and be pumped around the body. But because it has very little oxygen to distribute Arterial Hypoxemia develops. […] This problem can occur in different areas of the lungs, depending on where the pathogens settle. If it attacks a large portion of one or more lobes it is referred to as Lobular Pneumonia. But if it attacks many different patches along the bronchi and stretches out to the nearest parenchyma it is called Bronchopneumonia.

• #37 Pathogenesis of pneumonia and acute lung injury

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9429452/

  Bacterial pneumonia is categorized Community-acquired and Hospital-acquired pneumonia. […] Bacterial pathogens often have multiple virulence factors that allow them to evade or disrupt host defense mechanisms of the innate immune system. […] In addition to specific virulence factors of bacteria, whether bacteria are present as planktonic single-celled organisms or biofilm bacterial infections will impact the immune response. […] Secondary bacterial infections following a primary viral infection represent a potentially severe complication. […] The pulmonary airway and alveolar spaces have multiple mechanisms to protect the host from infection, and airway-specific factors provide a critical defense against infection. […] While mucus, ASL, and surfactant act as physical barriers that contain potent anti-microbial defense mechanisms, respiratory epithelial cells have a host of receptors located on the cell surface and intracellular compartments that are able to detect pathogen-associated molecular patterns (PAMP) and host-derived danger-associated molecular patterns (DAMP).

• #38 Bacterial Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300157-overview

  During pulmonary infection, acute inflammation results in the migration of neutrophils out of capillaries and into the air spaces, forming a marginated pool of neutrophils that is ready to respond when needed. These neutrophils phagocytize microbes and kill them with reactive oxygen species, antimicrobial proteins, and degradative enzymes. […] General mechanisms of increased virulence include the following: Genetic flexibility allowing the development of resistance to various classes of antibiotics; Flagellae and other bacterial appendages that facilitate spread of infection; Capsules resistant to attack by immune defense cells and that facilitate adhesion to host cells; Quorum sensing systems allow coordination of gene expression based on complex cell-signaling for adaptation to the local cellular environment; Iron scavenging.

• #39 Pathogenesis, Diagnosis and Therapeutic Strategies for Ventilator-associated Pneumonia – Journal of Pure and Applied Microbiology

  https://microbiologyjournal.org/pathogenesis-diagnosis-and-therapeutic-strategies-for-ventilator-associated-pneumonia/

  Few studies have revealed that use of contaminated respiratory therapy equipment in bronchoscopy and endoscopy can also be the reason for VAP infection. […] Pathogens can also make biofilms near the endotracheal tube and become highly resistant to antibiotics and host defense mechanisms. […] The presence of an endotracheal tube is one of the major culprits for VAP development: air flow moves pathogens toward the distal airways, while clearance of the trachea is blunted due to reduced tracheal ciliary movement and impaired cough. […] It is found that unsterilized contaminated hospital water and air can also infect critically ill patients.

• #40

  https://www.jci.org/articles/view/117631

  Streptococcus pneumoniae is one of the most common etiologic agents of community-acquired pneumonia, particularly bacteremic pneumonia. Pneumolysin, a multifunctional cytotoxin, is a putative virulence factor for S. pneumoniae; however, a direct role for pneumolysin in the early pathogenesis of pneumococcal pneumonia has not been confirmed in vivo. […] The presence of pneumolysin also contributed to the development of bacteremia, which was detected at 3 h after intratracheal instillation of PLY(+) bacteria. […] Thus, pneumolysin facilitates intraalveolar replication of pneumococci, penetration of bacteria from alveoli into the interstitium of the lung, and dissemination of pneumococci into the bloodstream during experimental pneumonia. Moreover, both the cytotoxic and the complement-activating activities of pneumolysin may contribute independently to the acute pulmonary injury and the high rates of bacteremia which characterize pneumococcal pneumonia.

• #41 Prevalence, pathogenesis, therapy, and prevention of cardiovascular events in patients with community-acquired pneumonia | Pneumonia | Full Text

  https://pneumonia.biomedcentral.com/articles/10.1186/s41479-016-0011-0

  The contention that platelet activation plays a pivotal role in orchestrating inflammatory events which trigger, or more likely exacerbate, vascular damage and dysfunction is supported by the steadily increasing recognition of the critical role played by these cells in mediating inflammatory and immune responses. […] Pro-inflammatory mechanisms by which platelet activation may contribute to the pathogenesis of bacterial CAP in particular have recently been reviewed elsewhere and are briefly considered and updated here. […] Pneumolysin is increasingly implicated in the pathogenesis of life-threatening acute cardiac complications in CAP, albeit based on data derived from experimental animal models. […] Given its dual mechanism of mediation of cardiac dysfunctionfirstly, direct damage to cardiomyocytes; and secondly, pro-inflammatory, pro-thrombotic actions involving activation of platelets and neutrophils and damage to vascular endotheliumpneumolysin appears to be a priority target in the prevention of CAP-associated CVEs.

• #42 The molecular mechanism of acute lung injury caused by Pseudomonas aeruginosa: from bacterial pathogenesis to host response | Journal of Intensive Care | Full Text

  https://jintensivecare.biomedcentral.com/articles/10.1186/2052-0492-2-10

  Pseudomonas aeruginosa is the most common gram-negative pathogen causing pneumonia in immunocompromised patients. […] Acute lung injury induced by bacterial exoproducts is associated with a poor outcome in P. aeruginosa pneumonia. […] The major pathogenic toxins among the exoproducts of P. aeruginosa and the mechanism by which they cause acute lung injury have been investigated: exoenzyme S and co-regulated toxins were found to contribute to acute lung injury. […] P. aeruginosa secretes these toxins through the recently defined type III secretion system (TTSS), by which gram-negative bacteria directly translocate toxins into the cytosol of target eukaryotic cells. […] Four type III secretory toxins, namely ExoS, ExoT, ExoU, and ExoY, have been identified in P. aeruginosa. […] ExoU, which exhibits phospholipase A2 activity activated by host cell ubiquitination after translocation, is a major pathogenic cytotoxin that causes alveolar epithelial injury and macrophage necrosis.

• #43 The molecular mechanism of acute lung injury caused by Pseudomonas aeruginosa: from bacterial pathogenesis to host response | Journal of Intensive Care | Full Text

  https://jintensivecare.biomedcentral.com/articles/10.1186/2052-0492-2-10

  The ExoU secretory phenotype is associated with a poor clinical outcome in P. aeruginosa pneumonia. […] Blockade of translocation by TTSS or inhibition of the enzymatic activity of translocated toxins has the potential to decrease acute lung injury and improve clinical outcome. […] Understanding the mechanism by which virulent strains of P. aeruginosa cause acute lung injury is critical for preventing subsequent sepsis and death. […] The ability of P. aeruginosa to cause acute lung epithelial injury and sepsis is highly linked to the expression of ExoU, regulated by the transcriptional activator ExsA. […] Through TTSS, P. aeruginosa translocates the type III secretory toxins ExoS, ExoT, ExoU, and ExoY. […] Of these four toxins, ExoU is the major virulence factor responsible for alveolar epithelial injury in P. aeruginosa pneumonia. […] The major pathogenesis of P. aeruginosa-induced acute epithelial lung injury and subsequent bacteremia and sepsis is highly dependent on the ExoU phenotype of the strain.

• #44 Viral Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300455-overview

  In addition to humoral responses, cell-mediated immunity appears to be important for recovery from certain respiratory viral infections. […] Impaired type 1 response may explain why immunocompromised patients have more severe viral pneumonias. […] Respiratory viruses damage the respiratory tract and stimulate the host to release multiple humoral factors, including histamine, leukotriene C4, and virus-specific IgE in RSV infection and bradykinin, interleukin (IL)1, IL-6, and IL-8 in rhinovirus infections. […] Infection by influenza virus leads to cell death, especially in the upper airway. When direct viral infection of lung parenchyma occurs, hemorrhage is seen along with a relative lack of inflammatory cells. Mucociliary clearance is impaired, and bacterial adherence to respiratory epithelium occurs.

• #45 Viral Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300455-overview

  Infection with the influenza virus impairs T lymphocytes, neutrophils, and macrophage function, which leads to impairment of host defenses and may foster bacterial infection of normally sterile areas, including the lower respiratory tract. This impairment of host defenses may explain why as many as 53% of outpatients with bacterial pneumonia have a concurrent viral infection. […] The receptor-binding domain (RBD) of the S protein of SARS-CoV-2 specifically recognizes the host angiotensin-converting enzyme 2 (ACE2) receptor. It is optimized for binding to the human receptor ACE2. Upon binding, host serine protease TMPRSS2 cleaves the S protein and results in the fusion of the viral and cellular membranes. […] Direct injury to the lung tissue from a viral infection mediated local inflammatory response is one of the proposed mechanisms behind the pulmonary manifestations of COVID-19.

• #46 Bacterial Pneumonia: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/300157-overview

  The association between infection with influenza virus and subsequent bacterial pneumonia became particularly apparent following the 1918 influenza pandemic, during which approximately 40-50 million people died. Historical investigations and current researchers argue that the vast majority of pulmonary-related deaths from past pandemic influenza viruses, most notably the pandemic of 1918, ultimately resulted from bacteriologic secondary or coinfection and poorly understood interactions between the infecting viral and bacterial organisms. […] Although pneumonia may be caused by myriad pathogens, a limited number of agents are responsible for most cases. Most authors categorize bacterial pneumonias by their infectious agents, which include pneumococcal agents; Haemophilus influenzae; Klebsiella, Staphylococcus, and Legionella species; gram-negative organisms; and aspirated micro-organisms.

• #47 The co-pathogenesis of influenza viruses with bacteria in the lung | Nature Reviews Microbiology

  https://www.nature.com/articles/nrmicro3231

  Mortality from influenza viruses is strongly linked to secondary bacterial invaders. In the most extreme example, more than 95% of the 50 million or more deaths during the 1918 pandemic were complicated by bacterial pneumonia. […] Disruption of lung physiology by respiratory viruses breaches natural barriers to infection and promotes bacterial co-infection. Receptors that can be used by bacteria for adherence and infection are uncovered and upregulated. […] Although they are typically secondary invaders during influenza infections, bacteria express virulence factors that promote viral pathogenesis. This results in increased viral load and decreased clearance. […] This co-pathogenesis is characterized by complex interactions between co-infecting pathogens and the host, leading to the disruption of physical barriers, dysregulation of immune responses and delays in a return to homeostasis. The net effect of this cascade can be the outgrowth of the pathogens, immune-mediated pathology and increased morbidity.

• #48 The co-pathogenesis of influenza viruses with bacteria in the lung | Nature Reviews Microbiology

  https://www.nature.com/articles/nrmicro3231

  Mortality from influenza viruses is strongly linked to secondary bacterial invaders. In the most extreme example, more than 95% of the 50 million or more deaths during the 1918 pandemic were complicated by bacterial pneumonia. […] Disruption of lung physiology by respiratory viruses breaches natural barriers to infection and promotes bacterial co-infection. Receptors that can be used by bacteria for adherence and infection are uncovered and upregulated. […] Although they are typically secondary invaders during influenza infections, bacteria express virulence factors that promote viral pathogenesis. This results in increased viral load and decreased clearance. […] This co-pathogenesis is characterized by complex interactions between co-infecting pathogens and the host, leading to the disruption of physical barriers, dysregulation of immune responses and delays in a return to homeostasis. The net effect of this cascade can be the outgrowth of the pathogens, immune-mediated pathology and increased morbidity.

• #49 Pneumonia – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/pneumonia/symptoms-causes/syc-20354204

  Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics and because the people who get it are already sick. […] Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs. […] Even with treatment, some people with pneumonia, especially those in high-risk groups, may experience complications, including: Bacteria that enter the bloodstream from your lungs can spread the infection to other organs, potentially causing organ failure. […] Pneumonia may cause fluid to build up in the thin space between layers of tissue that line the lungs and chest cavity (pleura). […] An abscess occurs if pus forms in a cavity in the lung.

• #50 Pneumonia: Causes, Symptoms, Diagnosis & Treatment

  https://my.clevelandclinic.org/health/diseases/4471-pneumonia

  Pneumonia is inflammation and fluid in your lungs caused by a bacterial, viral or fungal infection. Pneumonia causes your lung tissue to swell (inflammation) and can cause fluid or pus in your lungs. Bacterial pneumonia is usually more severe than viral pneumonia, which often resolves on its own. […] Pneumonia can develop when your immune system attacks an infection in the small sacs of your lung (alveoli). This causes your lungs to swell and leak fluids. […] Many bacteria, viruses and fungi can cause the infections that lead to pneumonia. Bacteria are the most common cause in adults and viruses are the most common cause in school-aged children. […] Pneumonia can lead to serious complications that can require hospitalization, including breathing difficulties. Pneumonia can lead to respiratory failure or acute respiratory distress syndrome (ARDS). […] If you have a severe case of pneumonia or complications, you may need to stay in the hospital for treatment.

• #51

  https://www.jci.org/articles/view/7124

  The pathogenesis of septic shock occurring after Pseudomonas aeruginosa pneumonia was studied in a rabbit model. The airspace instillation of the cytotoxic P. aeruginosa strain PA103 into the rabbit caused a consistent alveolar epithelial injury, progressive bacteremia, and septic shock. […] The lung instillation of a noncytotoxic, isogenic mutant strain (PA103UT), which is defective for production of type III secreted toxins, did not cause either systemic inflammatory response or septic shock, despite a potent inflammatory response in the lung. […] We conclude that injury to the alveolar epithelium allows the release of proinflammatory mediators into the circulation that are primarily responsible for septic shock. […] Our results demonstrate the importance of compartmentalization of inflammatory mediators in the lung, and the crucial role of bacterial cytotoxins in causing alveolar epithelial damage in the pathogenesis of acute septic shock in P. aeruginosa pneumonia.

• #52

  https://www.jci.org/articles/view/7124

  The role of circulating proinflammatory cytokines in the pathogenesis of septic shock has been well described. […] We therefore hypothesized that septic shock associated with P. aeruginosa pneumonia was secondary to the leak of mediators generated in the lungs crossing the injured epithelial barrier into the circulation. […] These investigations showed that instillation of PA103UT led to significantly elevated levels of TNF- in the BALF of rabbit lungs levels 10,000-fold higher than in the plasma of the same animals. […] The difference between TNF- levels in the airspaces and the plasma is consistent with the containment of TNF- within the lung by an intact epithelial barrier. […] Our investigation documents that significant bacterial-induced alveolar epithelial injury causes a progressive increase in circulating TNF- and IL-8 that is most likely due to leakage from the airspaces. […] The results are consistent with the interpretation that mediators leaked from the lung in response to bacterial cytotoxicity and contributed to the development of septic shock.

• #53 Pneumonia – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/pneumonia/symptoms-causes/syc-20354204

  Most pneumonia occurs when a breakdown in your body’s natural defenses allows germs to invade and multiply within your lungs. […] Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. […] Pneumonia can range in seriousness from mild to life-threatening. […] Many germs can cause pneumonia. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good. […] Pneumonia is classified according to the types of germs that cause it and where you got the infection. […] Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals or other health care facilities.

• #54 Epidemiology, pathogenesis, microbiology, and diagnosis of hospital-acquired and ventilator-associated pneumonia in adults – UpToDate

  https://www.uptodate.com/contents/epidemiology-pathogenesis-microbiology-and-diagnosis-of-hospital-acquired-and-ventilator-associated-pneumonia-in-adults

  Hospital-acquired (or nosocomial) pneumonia (HAP) and ventilator-associated pneumonia (VAP) remain important causes of morbidity and mortality despite improvements in prevention, antimicrobial therapy, and supportive care. […] The epidemiology, pathogenesis, and microbiology of HAP and VAP will be reviewed here. […] Ventilator-associated pneumonia (VAP) is a type of HAP that develops in intubated patients on mechanical ventilation for more than 48 hours. VAP also includes HAP that occurs within 48 hours after extubation.

• #55 Pathogenesis, Diagnosis and Therapeutic Strategies for Ventilator-associated Pneumonia – Journal of Pure and Applied Microbiology

  https://microbiologyjournal.org/pathogenesis-diagnosis-and-therapeutic-strategies-for-ventilator-associated-pneumonia/

  Ventilator-associated pneumonia (VAP) is a major health care associated infection which usually emanates from aspiration, immigration of pathogens from aerodigestive tract, adulterated appliance uses or medications. […] The ICU admitted patients who are ventilated, have several reasons like critical illness, comorbidities, and malnutrition that affect their immune system. […] Endotracheal intubations suppress the cough impulse, hamper muco-ciliary clearance, damage the tracheal epithelial surface and make a path for pathogenic bacteria which migrate from upper respiratory tract to lower respiratory tract. […] These pathogens then adhere to the mucosa of lower respiratory tract of mechanically ventilated patients and start infections. […] Generally, four routes are responsible for providing access to microorganisms in order to produce VAP infections a) Aspiration from oropharynx or from stomach into oropharynx then into the lower respiratory tract, b) Extension of contiguous infection, c) Contaminated air or ICU aerosol inhalation, and d) Vascular or urinary catheter-related blood-stream infection seeding the lungs.

• #56 Pathogenesis, Diagnosis and Therapeutic Strategies for Ventilator-associated Pneumonia – Journal of Pure and Applied Microbiology

  https://microbiologyjournal.org/pathogenesis-diagnosis-and-therapeutic-strategies-for-ventilator-associated-pneumonia/

  Few studies have revealed that use of contaminated respiratory therapy equipment in bronchoscopy and endoscopy can also be the reason for VAP infection. […] Pathogens can also make biofilms near the endotracheal tube and become highly resistant to antibiotics and host defense mechanisms. […] The presence of an endotracheal tube is one of the major culprits for VAP development: air flow moves pathogens toward the distal airways, while clearance of the trachea is blunted due to reduced tracheal ciliary movement and impaired cough. […] It is found that unsterilized contaminated hospital water and air can also infect critically ill patients.

• #57 Pneumonia | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-021-00259-0

  Pneumonia is a common acute respiratory infection that affects the alveoli and distal airways; it is a major health problem and associated with high morbidity and short-term and long-term mortality in all age groups worldwide. […] Development of the disease largely depends on the host immune response, with pathogen characteristics having a less prominent role. […] It is crucial to identify the causative pathogens, as delayed and inadequate antimicrobial therapy can lead to poor outcomes. […] New antibiotic and non-antibiotic therapies, in addition to rapid and accurate diagnostic tests that can detect pathogens and antibiotic resistance will improve the management of pneumonia. […] A reviewopinion article about new insights into the aetiopathogenesis of pneumonia based on changes in the microbiota. […] Mechanisms of bacterial colonization of the respiratory tract. […] Towards an ecology of the lung: new conceptual models of pulmonary microbiology and pneumonia pathogenesis.

• #58 Journal of Pulmonology and Respiratory Diseases – Molecular Mechanisms and Immune Responses in the Pathogenesis of Pneumonia: Insights into Bacterial and Viral Interactions

  https://www.omicsonline.org/open-access/molecular-mechanisms-and-immune-responses-in-the-pathogenesis-of-pneumonia-insights-into-bacterial-and-viral-interactions-134527.html

  The findings of this review illuminate the intricate interplay between bacterial and viral pathogens and the host immune system in the pathogenesis of pneumonia. Understanding these molecular mechanisms is vital for developing targeted therapies and preventive measures. […] Elevated levels of pro-inflammatory cytokines can result in ARDS, highlighting the importance of balancing immune activation and regulation. […] In conclusion, the pathogenesis of pneumonia represents a complex interplay between bacterial and viral pathogens and the host’s immune response. This review highlights the critical molecular mechanisms employed by various pathogens, including virulence factors that facilitate infection and strategies to evade immune detection. Understanding these interactions is essential for developing effective therapeutic interventions and preventive measures. […] The findings emphasize the importance of achieving a balanced immune response, which may involve novel therapeutic strategies aimed at modulating inflammation and enhancing host defense mechanisms.

• #59 Journal of Pulmonology and Respiratory Diseases – Molecular Mechanisms and Immune Responses in the Pathogenesis of Pneumonia: Insights into Bacterial and Viral Interactions

  https://www.omicsonline.org/open-access/molecular-mechanisms-and-immune-responses-in-the-pathogenesis-of-pneumonia-insights-into-bacterial-and-viral-interactions-134527.html

  The findings of this review illuminate the intricate interplay between bacterial and viral pathogens and the host immune system in the pathogenesis of pneumonia. Understanding these molecular mechanisms is vital for developing targeted therapies and preventive measures. […] Elevated levels of pro-inflammatory cytokines can result in ARDS, highlighting the importance of balancing immune activation and regulation. […] In conclusion, the pathogenesis of pneumonia represents a complex interplay between bacterial and viral pathogens and the host’s immune response. This review highlights the critical molecular mechanisms employed by various pathogens, including virulence factors that facilitate infection and strategies to evade immune detection. Understanding these interactions is essential for developing effective therapeutic interventions and preventive measures. […] The findings emphasize the importance of achieving a balanced immune response, which may involve novel therapeutic strategies aimed at modulating inflammation and enhancing host defense mechanisms.

• #60 Pneumonia | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-021-00259-0

  Pneumonia is a common acute respiratory infection that affects the alveoli and distal airways; it is a major health problem and associated with high morbidity and short-term and long-term mortality in all age groups worldwide. […] Development of the disease largely depends on the host immune response, with pathogen characteristics having a less prominent role. […] It is crucial to identify the causative pathogens, as delayed and inadequate antimicrobial therapy can lead to poor outcomes. […] New antibiotic and non-antibiotic therapies, in addition to rapid and accurate diagnostic tests that can detect pathogens and antibiotic resistance will improve the management of pneumonia. […] A reviewopinion article about new insights into the aetiopathogenesis of pneumonia based on changes in the microbiota. […] Mechanisms of bacterial colonization of the respiratory tract. […] Towards an ecology of the lung: new conceptual models of pulmonary microbiology and pneumonia pathogenesis.

• #61 Journal of Pulmonology and Respiratory Diseases – Molecular Mechanisms and Immune Responses in the Pathogenesis of Pneumonia: Insights into Bacterial and Viral Interactions

  https://www.omicsonline.org/open-access/molecular-mechanisms-and-immune-responses-in-the-pathogenesis-of-pneumonia-insights-into-bacterial-and-viral-interactions-134527.html

  The findings of this review illuminate the intricate interplay between bacterial and viral pathogens and the host immune system in the pathogenesis of pneumonia. Understanding these molecular mechanisms is vital for developing targeted therapies and preventive measures. […] Elevated levels of pro-inflammatory cytokines can result in ARDS, highlighting the importance of balancing immune activation and regulation. […] In conclusion, the pathogenesis of pneumonia represents a complex interplay between bacterial and viral pathogens and the host’s immune response. This review highlights the critical molecular mechanisms employed by various pathogens, including virulence factors that facilitate infection and strategies to evade immune detection. Understanding these interactions is essential for developing effective therapeutic interventions and preventive measures. […] The findings emphasize the importance of achieving a balanced immune response, which may involve novel therapeutic strategies aimed at modulating inflammation and enhancing host defense mechanisms.

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