Respiratory Tract Infection Flashcards
Pneumonia
- What is it?
- What are the symptoms?
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Pneumonia = infection of the lung parenchyma (actual lung tissue)
- This is the most common lethal adult infection (esp. elderly or chronically debilitated patients) -
Symptoms: Rapid
- Cough, chest pain, dyspnea
- Fever, sputum production
- May have chills or rigors, GI symptoms, mental status changes (might be the only symptom you see in immunosupressed elderly)
What is the physical exam like for pneumonia?
How do you diagnose pneumonia?
- Listen for rales (crackling) or evidence of **pulmonary consolidation **
- Diagnosis requires CXR or CT scan
- Looking for diffuse or consolidated infiltrates (alveolar or intersitial) or cavitation
- Might also see pleural effusion/empyema
*The radiologists can’t differentiate between bacterial and non-bacterial pneumonia! It is up to you to determine the difference using cultures and clinical history
What is the pathology of pneumonia?
- Bacterial pneumonia: lots of alveolar exudative inflammation from neutrophils
- Atypical pneumonia: mycoplasma, chlmydophylia, or viruses
- Necrotizing granulomas are fungi or mycobacteria (TB) until proven otherwise
What is the difference between bronchopneumonia and lobar pneumonia?
Bronchopneumonia is splotchy spans the lobes
Lobar pneumonia is continuous and stays within the lobes
What does a lung abscess look like on CXR?
It appears with an air/fluid line or small air space because it will be draining fluid and forming a small pocket of air
*Staph aureus loves abscesses so if you locate one on X-ray, you must open it and drain it.
What studies can you use to look at pneumonia rapidly?
- Pulse oximetry: Might show desaturation because of damage or infiltrates in the interstitium/alveoli
- Leukocytosis (neutrophilic) in the WBC
- Increased ESR and CRP
- Sputum gram stain and urinary antigen test (Look for antigens to pneumococus and legionella in the urine)
*Urinary antigen will be available much faster than a gram stain!
What are the predisposing factors of pneumonia?
- Extremes of age (elderly are very susceptible)
- Altered consciousness (increased aspiration risk)
- Cigarette smoking: paralyze cilia and increase mucus secretions
- COPD
- Pulmonary edema
- Malnutrition
- Immunosuppression: aquired or congenital
- Cystic Fibrosis
- Immotile cilia syndrome
- Bronchial obstruction (tumor, foreign body, stenosis, etc.)
- Viral respiratory infection leading to bacterial pneumonia (influenza)
How is pneumonia classifed?
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Clinical classification scheme:
- Community acquired: 95% cure rate
- Hospital/nosocomial:
- Immunocompromised
- Immunocompromised with chronic pneumonia (esp. from TB and fungi (Blastomycoses) -
Severity index: mild, moderate, or severe disease
- tells you if you should admit or not (admit for anything above mild disease)
Do the elderly and infants always show with a high white count during sepsis or pneumonia?
No, they may exhibit leukopenia (no white count elevation) and be afebrile!
How do you diagnose the microbial organism and treat in pneumonia?
- Truth is you will do a lot of empirical antibiotic therapy (just don’t know what bug it is and have to act fast)
- In everyday practice, the causative bug is found only 10-20% of the time and can be determined in only 50-60% of patients!
- For most community aquired pneumonia, empiric antibiotics are effective in >95% of the patients (both common and atypical organisms)
Diagnosis Options:
- Sputum from a deep cough (do Gram stain, KOH/silver, culture it, or do PCR)
- Blood culture: if it’s positive for something then that is the probably the offending organism
- Culture any pleural/empyema fluid or lung abscess
- Urinary antigen testing: pneumococcus and legionella, histoplasmosis
- Lung biopsy
- Serology
- Procalcitonin serum test: Increases in bacterial infection but not viral disease
Once you isolate an organism in the culture, you must differentiate between organisms that normally colonize the respiratory tract vs those that are not known to colonize. What are the bugs that are always regarded as causative of infection?
Legionella
Influenza virus
M. tuberculosis
C. psittaci
Agents of bioterrorism: B. anthracis, Yersinia pestis (pneumonic plague), Francisella tularensis (tularemia). Coxiella burnetti (Q Fever), Hanta virus
What fungal organisms are known to be causal agents of respiratory infections?
Why does differentiating them from bacteria matter?
Histoplasmosa
Blastomyces
Coccidioides
These fungi all need treatment different from the normal empiric antibiotics
What are the most common causative organisms of community-acquired pneumonia?
What is the most common organism of non-epidemic pneumonia?
- Strept. pneumonia, Mycoplasma pneumoniae, Chlamydophilia pneumonia, Legionella, respiratory viruses
- Strept. pneumonia (pneumococcus)
What are the most common organisms for ICU admission pneumonia?
If the patient had a prior influenza, antibiotic prescription, or chronic pulmonary disease, what are the most common organsims?
- Gram (-) bacilli, S. aureus, Legionella, H. influenza, respiratory viruses
- S. aureus, enterobacteria, pseudomonas aeruginosa
What are the most common viral causes of community acquired pneumonia
Influenza A, B, and avian
- RSV in kids
diagnose using PCR, also think of whether these are the causative organsims or simply secondary to immunosuppresion
