Community Acquired Pneumonia Flashcards
Etiopathogenesis of Community-acquired-Pneumonia
- Lower respiratory tract infetion acquired in the community within 24 hours or less than 2 weeks
- Results from the proliferration of microbial pathogens at the alveolar level and the host’s response to those pathogens
- Classic pneumonia (lobar pneumococcal pneumonia) evolves through a series of changes
Most common access of microorganisms to the LRT
aspiration from the oropharynx
Phases of CAP
- Edema
- Red Hepatization
- gray Heaptization
- Resolution (final phase)
Edema Phase of CAP
- Initial phase with the presenc eof a proteinaceous exudtae, and often a bacteria in the alveoli
Red Hepatization
- Presence of erythrocytes in the cellular intraalveolar exudate
- Neutrophil influx is more important from the standpoimt of host defense
- Bacteria are occasionally seen in pathologic specimens
Gray Hepatization
- No new erythrocytes are extravasating and those already have been lysed and degraded
- The neutrophil is the predominant cell, fibrin deposition is abundant, and bacteria have disappeared
- Corresponds with successful containment of the infection and improvement of gas exchange
Resolution
- 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
Manifrstations of CAP
- commonly presents with acute cough, abnormal vital signs of tachypnea, tachycardia, and fever with at least one abnormal chest finding f diminished breath sounds, ronhi, crackles, or wheeze
Classification and Disposition of CAP
Chest Xray for CAP
- Essential in diagnosis of CAP, assessing severity, differentiating pneumonia from other conditions and in prognostication
- Best radiologic evaluation cosists of standing posteroanterior and lateral views
- Does not predict the likely etiologic agents
Sputum Gram Stain and Culture
- Strongly indluenced by the quality of collection, transport, and processing
- Main purpose of gram stain is to ensure that a sample is suitable for culture
Adequate sputum sample
- >25 neutrophils/LPF
- <10 squamous epithelial cells/LPF
Blood culture for CAP
- Yield is relatively low, therfore it is optional for hospitalized patients
- Most common isolate: S. pneumoniae
- Strongest indication for blood cultures: severe CAP (more likely be infected with S. aureus, P. aeruginosa, other gram negative bacilli)
Invasive procedures
- transtracheal
- Transthoracic biopsy
- Bronchoalveolar lavage
- Proteted brush specimen
- Options for non-resolving pneumonia, immunocopmpromised patients, and in patients in whom no adequate respiratory specimens can be sent despite sputum induction androutine diagnostic testing
- Most clear cut indication for extensive diagnostic testing is in the critically-ill CAP patient
Pneumonia Risk Score
- CURB-65
- Predicts mortality in CAP
Empiric Microbial Therapy for Low risk CAP
Empiric Management Therapy for Moderate Risk CAP
Empiric Treatment for igh Risk CAP
- (Piperacillin-tazobactam IV or Cefepime IV or Meropenem IV) + Azithromycin IV + (Gentamicin IV) or Amikacin
- (Piperacillin-tazobactam IV or Cefepime IV or Meropenem IV) + (ciprofloxacin IV or Levofloxacin IV)
Common Antibiotics Used in CAP
Duration of treatment for CAP
(most bacterial pneumonias)
5-7 days (3-5 for azalides for S. pneumoniae)
Duration of treatment for CAP
(MSSA-CAP)
7-14 days (up to 21 days if bacteremic)
Duration of treatment for CAP
(MRSA-CAP)
7-21 days (up to 28 days if bacteremic)
Duration of treatment for CAP
(P. aeruginosa)
14-21 days (up to 28 days if bacteremic)
Duration of treatment for CAP
(Mycoplsasma and Chlamydophila)
10-14 days
Duration of treatment for CAP
(Legionella)
14-21 days (10 for azalides)
Discharge criteria for CAP
- during the 24 hours before discharge, the patient should have:
- Temperature of 36-37.5 degrees celsius
- Pulse <100/min
- RR between 16-24/min
- SBP >90 mmHg
- Blood O2 saturation >90%
- Functioning GI tract (allowing use of oral antibiotics)
