What are the various routes of infection to the lungs?
- Inhalation of contaminated droplets/aerosols
- Direct extension
What are host defenses to lung infections?
- Anatomical (nasal turbinates, nasal hairs, glottis, branching airways)
- Cough reflex
- Mucociliary escalator
Immune-based responses: alveolar macrophages and surfactant proteins
- Engulf, opsonize and kill bacteria and viruses
- Release inflammatory mediators to defend the lung =>syndrome of pneumonia
What are risk factors for community acquired pneumonia?
- Age > 70
Clinical manifestations of CAP?
Onset/prodrome: insidious, acute or fulminant
Severity: mild to fatal
- Fever, cough (dry or productive), pleuritic chest pain, chills or rigors, shortness of breath
- Associated symptoms: HA, nausea, vomiting, diarrhea, myalgia, fatigue
What is found on the physical exam of pt with pneumonia?
- Fremitus – increased or decreased
- Percussion – dull or flat
- Pleural friction rub
- Whispered pectoriloquy (increased clarity of whispered words; same connotation as bronchopony)
- Egophony – E to A (extreme bronchophony)
What are the typical etiologic agents of community acquired pneumonia? Atypical?
- Strep pneumoniae
- Hemophilus influenzae
- Staph aureus
- Klebsiella pneumoniae
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella spp
- Respiratory viruses
Vary according to geographic areas, patient population, season, age group
(Only find etiologic agent in 1/2 of outpts or 2/3 of inpts.. in everyday practice, 70% of cases are not identified)
What common pathogens are associated with alcoholism?
- S pneumoniae
- Oral anaerobes
Gram negative bacilli:
- M TB
What common pathogens are associated with bronchiectasis, cystic fibrosis?
- Burkholderia cepacia
- Staph aureus
What common pathogens are associated with COPD?
- H influenzae
- S pneumoniae
- Moraxella catarrhalis
What common pathogens are associated with Flu season?
- Influenza virus
- S pneumoniae
- Staph aureus
What common pathogens are associated with exposure to water?
What common pathogens are associated with poor dental hygiene?
What common pathogens are associated with HIV?
- Pneumocystis jirovecii
- Strep pneumoniae
- Mycobaterium tuberculosis
- H influenzae
How is a CXR useful in pneumonia?
Helpful in diagnosis
- Presence/extent of infiltrate
- Presence of pleural effusion
- Follow clearing of infiltrate
When would you order a CT chest?
- Complicating factor
- Negative CXR with strong suspicion for pneumonia
What are other tests that can be used in diagnosis/management of pneumonia?
WBC count: indicate need for hospitalization (very high or very low)
Sputum Gram stain:
- Adequate lower respiratory tract specimen: fewer than 10 squamous epithelial cells and >25 PMNs per LPF
- Can identify organisms by characteristic appearance
Blood culture (if admitted to hospital), low yield: 5-14%
Antigen tests: uine strep and legionella
PCR tests: Rapid flu, M TB, Legionella, Mycoplasma
Serology: mycoplasma, viruses, fungi
What is the pneumonia severity index (PSI)?
20 variables with points assigned
Severity classes I-V for point ranges with associated mortality rates
What is the CURB 65 criteria?
- Urea > 7 mmol/L
- Respiratory rate > 30
- Blood pressure: SBP under 90 or DBP under 60
- Age > 65
How do you select antibiotics for CAP?
Strep pneumoniae: cephalosporin
Atypical pathogens: macrolide
- Evaluate risk factors for drug resistance (risk factors for community-acquired MRSA)
- Treatment should start as soon as possible
What is nosocomial pneumonia?
- Pneumonia development at least 48 hours after hospital admission
What is healthcare associated pneumonia?
- Transition between nosocomial and community acquired pneumonia
- Up to three months after health care episode (admitted for at least 2 days)
- Residence in NH
- IV antibiotics, chemo or wound care within 30 days
- Attended hemodialysis in hospital or clinic
What are common etiologies for healthcare associated pneumonia?
(Similar to nosocomial pneumonia)
Gram negative bacilli: 64%
- E coli
- Pseudomonas (21%)
- Staph aureus- most common single pathogen! (MRSA > 50%)
Complications of pneumonia?
- Pleural effusion – parapneumonic or empyema
- Lung abscess
- Metastatic infection
- Respiratory failure
- Septic shock
- Multiple organ failure
What immunocompromised patients/situations should be considered with pneumonia?
- HIV infection
- Organ transplantation: bone marrow and solid organs
- Malignancies: related to malignancy or its treatment (leukopenia, altered mentation, aspiration, emesis)
- Autoimmune diseases/Tx: steroids, anti-TNF
Nuances of pneumonia in immunocompromised host:
- Net state of immunosuppression” – host factors that contribute to infectious risk
- Fever may or may not be present
- Rate of progression of disease
- Radiographic pattern may be abnormal
- Aggressive diagnostic measures
---- Specific etiologic diagnosis is essential
---- Differential dx includes non-infectious processes
- Immediate treatment intervention
What etiologic causes of pneumonia or worrisome in the different stages of lung transplants?
Early (under 1 mo)
- Nosocomial pathogens
Middle (1-4 mo)
Late (> 6 mo)
- Granulomatous: nocardia, reactivation of fungi, mycobacteria
Epidemic of _____ is a looming threat to TB control efforts
Epidemic of diabetes mellitus is a looming threat to TB control efforts
What are risks for TB infection?
- Close contact of person with TB
- Persons from or frequent visitors to countries of high TB burden
- Congregate settings – residents and employees
- Health care workers
- Low income, drug/alcohol abuse, poor access to health care
- Infants, children, adolescents
What is MDR-TB?
Multi-drug resistant TB Resistance to both:
What are characteristics of a latent TB infection (LTBI)?
- History of exposure to TB
- No symptoms
- Immune response to TB antigens
----Positive TST or
----Positive interferon gamma release assay (IGRA) – Quantiferon TB or T Spot TB
- Normal CXR
What are high risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
- HIV or immunosuppressed
- Close contact of TB pt
- Abnormal CXR
Positive > 5mm
What are moderate risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
- Recently infected (under 2 yrs) = recent converter
- High risk medical conditions: DM, cancer of head/neck, lung, organ transplant
Positive > 10 mm
What are low risk groups for TB? What is considered positive on a tuberculin skin test (TST)?
None of the other conditions (HIV/immunosuppressed, close contact, abnromal CXR, high risk medical conditions like DM, cancer, organ transplant...)
Positive > 15 mm
What is the natural history/course of LTBI in an HIV negative pt?
- No further problem with no evidence of active disease (90%)
- Primary infection is not well contained and active disease develops within 2 years (lower lobe, hilar, pleural) (5%)
- "Reactivation of previously contained, dormant TB (usually > 2 years after primary infection (5%)
What is the natural history/course of LTBI in an HIV pt?
Risk for active TB: 7-10% per year
Treatment of LTBI?
- Standard therapy: 4 first line drugs
---- Intensive phase = RIPE (Rifampin, Isoniazid, Pyrazinamide, Ethambutol) for 2 mo
----- Continuation phase = RI for 4 mo
- Provide safest, most effective therapy in shortest time: decrease infectivity, morbidity mortality
- Adherence to therapy- DOT, in all
- Major determinant of outcome is adherence and completion
- Children treated same as adults
- Extrapulmonary TB treated the same
- Contact investigation = key to dz prevention (pic 2)
What are risks for active TB?
- Previously untreated TB (stable, fibrotic pulmonary lesion)
- Use of anti-TNF, chronic steroids
- Malignancy – head and neck, lung
- Chronic renal failure
- Diabetes mellitus
- Active smoker
- Post gastrectomy
Characteristics of primary TB (pathologically/anatomically)?
- Lower lobe involvement
- Pneumonic pattern
- Hilar LAD
- Pleural effusion
Characteristics of reactivation TB (who gets it, sites, anatomy)
- Majority of pts with active TB
- Endogenous reactivation of latent infection
- Occurs in sites that were disseminated during the primary infection
- Most common site = apical posterior segment of lung (80%)
What clinical features aid in the diagnosis of TB?
- Risk factors for exposure
- Signs and symptoms: usually chronic (wks - mos) and non-specific
- Persistant cough
- Malaise, fatigue
- Weight loss, anorexia
- Night sweats
How can the microbiologic diagnosis be made for TB?
Acid fast stain: Ziehl Neelsen or auramine fluorescence
- Three sputum specimens ~50% positive
- Culture: 2-6 weeks
- Drug susceptibility: 1-2 weeks
- Nucleic acid amplification – PCR based
- Drug susceptibility – detect gene mutation
How can therapy be monitored?
Monthly sputum culture until negative
- 80% are culture negative in 2 months
- If positive > 2 months, repeat susceptibility
Serial CXR are not recommended
- End of treatment CXR – future comparison
Clinical evaluation monthly
- Adverse reactions and adherence to therapy
Treat co-morbidity – DM, COPD, HIV
- Emerging threats to global TB control
- Treatment of LTBI – important role in TB elimination
- Clinical presentation of TB is varied
- Close clinical follow up and partnership with public health department – ensure completion of treatment
- Clinical manifestations of pneumonia are non-specific
- Epidemiologic factors are useful in narrowing the possible etiologic agents
- Treatment should be directed to the most likely pathogen(s) and initiated without delay
- Clinical features that predict mortality help guide decision for hospitalization