9/11- Pulmonary Infections Flashcards
What are the various routes of infection to the lungs?
- Inhalation of contaminated droplets/aerosols
- Aspiration
- Hematogenous
- Direct extension
What are host defenses to lung infections?
Mechanical
- 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?
- Alcoholism
- Asthma
- Immunosuppression
- Institutionalization
- Age > 70
Clinical manifestations of CAP?
Onset/prodrome: insidious, acute or fulminant
Severity: mild to fatal
Symptoms:
- 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?
- Tachypnea
- Fremitus – increased or decreased
- Percussion – dull or flat
- Crackles
- 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?
Typical:
- Strep pneumoniae
- Hemophilus influenzae
- Staph aureus
- CA-MRSA
- Klebsiella pneumoniae
Atypical:
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella spp
- Respiratory viruses
- Fungi
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:
- Klebsiella
- Acinetobacter
- M TB
What common pathogens are associated with bronchiectasis, cystic fibrosis?
- Pseudomonas
- Burkholderia cepacia
- Staph aureus
What common pathogens are associated with COPD?
- H influenzae
- Pseudomonas
- Legionella
- 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?
Legionella spp
What common pathogens are associated with poor dental hygiene?
Oral anaerobes
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
Sputum culture
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?
- Confusion
- Urea > 7 mmol/L
- Respiratory rate > 30
- Blood pressure: SBP under 90 or DBP under 60
- Age > 65
Mortality rate:
1- 1.5%
2- 9.2%
3- 22%
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?
HAP, VAP
- 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%)
- Klebsiella
- Enterobacter
Gram positives
- 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:
- Defenses
- Fever?
- CXR
- Tx?
- 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)
- Bacteria
- Aspiration
- Nosocomial pathogens
Middle (1-4 mo)
- Pneumocystic
- Aspergillus
- CMV
Late (> 6 mo)
- Pneumocystis
- 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:
- Isoniazide
- Rifampin
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)
- HIV
- Silicosis
- Use of anti-TNF, chronic steroids
- Malignancy – head and neck, lung
- Chronic renal failure
- Diabetes mellitus
- Alcoholism
- Active smoker
- Malnutrition
- 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
Pulmonary Sx:
- Persistant cough
- Hemoptysis
- Dyspnea
Systemic Sx:
- Malaise, fatigue
- Fever
- 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
Molecular technology
- 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
Supportive environment
SUMMARY
- 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
