Lower Respiratory Tract Infections

BRONCHITIS

Dx:  Acute wheezes, rhonchi, &/or prolonged expiratory phase
  • No fever or rales (would = pneumonia)
  • Normal CXR  (if obtained)
Differential Dx:
  • Viral (most likely)
  • Asthma (if Hx recurrent episodes)
  • COPD Exacerbation (if COPD + new purulent sputum)
  • Pertussis (clear lungs, paroxysmal cough)
    • Tx Pertussis if contact w/ unimmunized infant
Antibiotic Tx:  NONE !!!!!
  • Treat w/ inhalers
  • If really considering Pertussis:  Azithromycin
  • COPD Exacerbation:  Macrolide, Amoxicillin, Cefuroxime, OR Doxycycline
    • If frequent recurrences, vary antibiotic

See postings Acute Cough – 1 (re: Pertussis); Acute Cough – 2 (re: Bronchitis)

COMMUNITY-ACQUIRED PNEUMONIA

Dx:  Fever with Focal Rales
  • Get CXR in adults & children <5 y.o.; empiric Dx in other kids

Empiric Out-Patient Antibiotic Treatment

DiagnosisDude recommends:
  • Doxycycline (if >8 y.o.); OR
  • Amoxicillin-clavulanate, high-dose (4 gm/d) ± a macrolide
  • Levofloxacin for adults w/ multiple comorbidities
North American Guidelines (2007; IDSA & ATS)
  • Otherwise-Healthy:  Macrolide (Doxycycline acceptable)
  • Patients with Risk of Drug-Resistant Pneumococcus
    • Levofloxacin; OR
    • Amoxicillin-clavulanate (high-dose) plus a macrolide
British Thoracic Society & Amer. Acad. Pediatrics
  • Amoxicillin 500 mg – 1,000 mg T.I.D. (90 mg/kg/d)
  • Pen-Allergic: a Macrolide
¶  Risk of Drug-Resistant Pneumococcus:
•  Antibiotics within past 3 months    •  Hospitalization within past month
•  Alcoholism              •  Immunocompromise            •  Homeless Shelters
•  Long-term care facilities                  •  Multiple medical co-morbidities
•  Exposure to day-care (or to a child in day-care)  [???????]
 

Microbiology of Community-Acquired Pneumonia

Conceptualized as “Pyogenic” vs. “Atypical” Pneumonia
  • Pyogenic: Abrupt onset, Purulent Sputum, Rales (focal), Consolidation (CXR)
  • Atypical:  Gradual onset, Interstitial Infiltrates
  • NOTE:  Lots of overlap; can’t differentiate easily
  • NOTE:  “Atypical” can be equally serious

Pyogenic Pneumonia  —  the Bugs

Common
•  Pneumococcus
•  H. flu
 
Uncommon
•  Strep pyogenes
•  Staph aureus
•  E. coli & other enterics
•  Klebsiella pneumoniae
•  Pseudomonas
 
 
VERY Rare (hopefully)
•  Anthrax, plague, tularemia, hantavirus, Q fever, SARS
Comments
> Community Acquired Pneumonia (CAP)
> CAP
 
 
> CAP, Complication of Influenza
> IV drug user; Complication of Influenza
> Nosocomial; debilitated
> Diabetes, cancer, alcoholics
> Underlying lung disorder; nosocomial; immunocompromomised
 
 
> Agents of Bioterrorism (Very ill; CXR variable)

“Atypical” Pneumonia  —  the Bugs

Common
•  Mycoplasma pneumoniae
•  Chlamydophila  pneumoniae
     – aka Chlamydia pneumoniae
•  Viral influenza
  
Less Common
•  Legionnaires’
 
 
•  Tuberculosis
•  Endemic fungi
     – histoplasmosis,
  blastomycosis
     – coccidioidomycisis
•  Psittacosis
•  Pneumocystis
Comments
> Usually youngish
> Usually middle-aged or older
 
> Anybody
  
 
> Common-source outbreaks
(e.g. water coolers)  [Usually ill enough to need admission]
> Lived in endemic areas
> Lived in endemic areas
     – Ohio River Valley, 3rd World
 
     – Calif. Central Valley, Arizona
> Parrot exposure
> AIDS, organ transplants, etc.

See posting Infectious Disease – 3.

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