Chapter 10: Lower Respiratory Tract Infections

Acute Bronchitis

Common Causes:

• Viruses: Influenza A/B, parainfluenza, coronavirus, rhinovirus, RSV, adenovirus, human metapneumovirus
• Bacteria: Bordetella pertussis, Mycoplasma pneumoniae, Chlamydophila pneumoniae

Management:

• Symptomatic treatment only (antibiotics not indicated for viral bronchitis)
• Treat pertussis to reduce spread, even if onset >7 days ago‍

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Acute Exacerbation of Chronic Bronchitis (COPD)

Bacterial Causes:

• S. pneumoniae, M. catarrhalis, H. influenzae

Treatment:

Amoxicillin-clavulanate (PO or IV), ceftriaxone IV, or moxifloxacin depending on severity and setting.

Bronchiolitis

• Mostly affects infants <2 years
• Most common cause: RSV
• Treatment: supportive (fluids, oxygen, suctioning)
• Consider ribavirin in immunocompromised cases

Community-Acquired Pneumonia (CAP)

Common Pathogens:

• Streptococcus pneumoniae
• Haemophilus influenzae
• Atypicals: Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila
• Staphylococcus aureus (severe cases)
• Mycobacterium tuberculosis (always consider in SA)

Outpatient Treatment

• Age <65, no comorbidities:
  Amoxicillin 1 g PO 8-hourly for ≥5 days (until afebrile ≥36–48h)
• Age >65 or with comorbidities:
  Amox-clav 1 g PO 12-hourly OR respiratory fluoroquinolone

Hospitalised (Non-ICU)

• Amox-clav 1.2 g IV 8-hourly OR Ceftriaxone 2 g IV daily
  PLUS
  • Clarithromycin 500 mg IV 12-hourly OR
  • Azithromycin 500 mg IV daily

ICU Patients

• Beta-lactam (e.g., ceftriaxone, amox-clav, ertapenem)
  PLUS macrolide (clarithromycin or azithromycin)
  ± Aminoglycoside if Gram-negative coverage needed

Atypical Pneumonia

Common Pathogens:

• Mycoplasma pneumoniae
• Chlamydia pneumoniae
• Legionella pneumophila

Treatment Options:‍


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Aspiration Pneumonia

• Coverage should include anaerobes.
• Preferred regimens:
  • Amox-clav 1.2 g IV 8-hourly
  • Ceftriaxone + metronidazole
  • Piperacillin-tazobactam 4.5 g IV 6-hourly (or continuous infusion)

Pneumonia in Immunocompromised Hosts

• Always consider Pneumocystis jirovecii pneumonia (PJP) in HIV-positive patients with low CD4

Treatment for PJP:

• Cotrimoxazole 15–30 mg TMP/kg/day ÷ q6h IV or 2 DS PO 8-hourly × 21 days
• Add prednisone 40 mg PO BD x 5 days, then taper

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