Problem 2 Flashcards
What if the patient is old, allergic to penicillin with comorbidities
clarithromycine
What is pneumonia
infection of the pulmonary parenchyma
What is health-care associated pneumonia
CAP but the patient has multi-drug resistant pathogen associated with HAP
Pneumonia results from…
Proliferation of microbial pathogens at the alveolar level and the host’s response to those pathogens.
How does the pathogen get to the lower airways
The most common is by aspiration from the oropharynx. Small-volume aspiration occurs frequently during sleep (especially in the elderly) and in patients with decreased levels of consciousness.
Rarely, pneumonia occurs via hematogenous spread (e.g., from tricuspid endocarditis) or by contiguous extension from an infected pleural or mediastinal space.
How does the body protect us from pneumonia
Mechanical factors:
-the hairs and turbinates of the nares capture larger inhaled particles before they reach the lower respiratory tract.
-The branching architecture of the tracheobronchial tree traps microbes on the airway lining, where mucociliary clearance and local antibacterial factors either clear or kill the potential pathogen.
-The gag and cough reflexes offer critical protection from aspiration.
In addition, the normal flora adhering to mucosal cells of the oropharynx, whose components are remarkably constant, prevents pathogenic bacteria from binding.
-When these barriers are overcome or when microorganisms are small enough to be inhaled to the alveolar level, resident alveolar macrophages are
extremely efficient at clearing and killing pathogens. Macrophages are assisted by proteins that are produced by the alveolar epithelial cells (e.g.,
surfactant proteins A and D) and that have intrinsic opsonizing properties or antibacterial or antiviral activity. Once engulfed by the macrophage, the
pathogens—even if they are not killed—are eliminated via either the mucociliary elevator or the lymphatics and no longer represent an infectious challenge.
What triggers the clinical syndrome of pneumonia
The host inflammatory response
What causes the fever
The release of inflammatory mediators, such as interleukin 1 and TNF
What causes peripheral leukocytosis and increased purulent production
Chemokines, such as interleukin 8 and granulocyte colony-stimulating factor, stimulate the release of neutrophils and their attraction to the lung
What causes hemoptysis
erythrocytes can cross the alveolar–capillary
membrane because of the capillary leaks
What causes the radiographic infiltrate and rales detectable on auscultation
Capillary leaks
Why does the patient have hypoxemia
alveolar filling
but also some bacterial pathogens appear to interfere with the hypoxemic vasoconstriction that would normally occur with fluid-filled alveoli
What leads to dyspnea
Decreased compliance due to capillary leak
Hypoxemia
Increased respiratory drive
Increased secretions
Occasionally infection-related bronchospasm
What happens if the changes in lung mechanics are severe enough
the changes in lung mechanics secondary to
reductions in lung volume and compliance and the intrapulmonary shunting of blood may cause respiratory failure and death.
What is the alternative pathogenesis pathway
The alveolar microbiota is similar to the oropharyngeal microbiota; both are predominantly gram-positive in contrast to the gram-negative milieu of the normal gastrointestinal microbiota. Alterations in host defense may allow overgrowth of one or more components of the normal bacterial flora.
What are the 2 most common causes to an altered alveolar microbiota
viral upper respiratory tract infections for CAP
and antibiotic therapy for HAP/VAP.
What is the initial phase of pneumonia
The initial phase is one of edema, with the presence of a proteinaceous exudate— and often of bacteria—in the alveoli. This phase is rarely evident in clinical or autopsy specimens because of the rapid transition.
What is the second phase of pneumonia
The red hepatization phase. The presence of erythrocytes in the cellular intra-alveolar exudate gives this second stage its name, but neutrophil influx is more important with regard to host defense. Bacteria are occasionally seen in pathologic specimens collected during this phase.
What is the third phase of pneumonia
In the third phase, gray hepatization, no new erythrocytes are extravasating, and those already present have been lysed and degraded. The neutrophil is the predominant cell, fibrin deposition is abundant, and bacteria have disappeared. This phase corresponds with successful containment of the infection and improvement in gas exchange.
What is the final phase of pneumonia
In the final phase, resolution, the macrophage reappears as the dominant cell type in the alveolar space, and the debris of neutrophils, bacteria, and fibrin has been cleared, as has the inflammatory response.
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This pattern has been described best for lobar pneumococcal pneumonia and may not apply to pneumonia of all etiologies, especially viral or
Pneumocystis pneumonia. In VAP, respiratory bronchiolitis may precede the development of a radiologically apparent infiltrate. Because of the
microaspiration mechanism, a bronchopneumonia pattern is most common in nosocomial pneumonias, whereas a lobar pattern is more common in
bacterial CAP. Despite the radiographic appearance, viral and Pneumocystis pneumonias represent alveolar rather than interstitial processes.
What is the most common pathogen causing CAP
Streptococcus pneumoniae
Typical pathogens causing pneumonia
S. pneumoniae
Haemophilus influenzae
(in selected patients) S. aureus
Gram-negative bacilli such as Klebsiella pneumoniae and Pseudomonas aeruginosa.
Atypical pathogens causing pneumonia
Mycoplasma pneumoniae
Chlamydia pneumoniae
Legionella species
Respiratory viruses such as influenza viruses, adenoviruses, human metapneumovirus, and respiratory syncytial viruses.