Pulmonary antibiotics



Coverage targeted at S. pneumoniae, H. influenzae. M. pneumoniae, C. pneumoniae, and Legionella


No comorbidities (chronic heart, lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancy; or asplenia) and no or risk factors for MRSA or Pseudomonas aeruginosa (include prior respiratory isolation of MRSA or P. aeruginosa or recent hospitalization AND receipt of parenteral antibiotics (in the last 90 d))

  • Amoxicillin 1 g three times daily (strong recommendation, moderate quality of evidence), OR
  • Doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence), OR
  • Macrolide in areas with pneumococcal resistance to macrolides <25% (conditional recommendation, moderate quality of evidence).
  • Duration of therapy 5 days minimum


If patient has comorbidities or risk factors for MRSA or Pseudomonas aeruginosa

  • Combination therapy:
    • Amoxicillin/Clavulanate
      • 500 mg/125 mg TID OR amox/clav 875 mg/125 mg BID OR 2,000 mg/125 mg BID. Duration is for a minimum of 5 days and varies based on disease severity and response to therapy; patients should be afebrile for ≥48 hours and clinically stable before therapy is discontinued[3]
    • OR cephalosporin
    • AND macrolide
      • Azithromycin 500 mg on first day then 250 mg daily
      • OR clarithromycin 500 mg BID OR clarithromycin ER 1,000 mg daily]) (strong recommendation, moderate quality of evidence for combination therapy)
    • OR doxycycline 100 mg BID (conditional recommendation, low quality of evidence for combination therapy)
  • Monotherapy: respiratory fluoroquinolone (strong recommendation, moderate quality of evidence):


  • Monotherapy or combination therapy is acceptable
  • Combination therapy includes a cephalosporin and macrolide targeting atypicals and Strep Pneumonia [4]
  • The use of adjunctive corticosteroids (methylprednisolone 0.5 mg/kg IV BID x 5d) in CAP of moderate-high severity (PSI Score IV or V; CURB-65 ≥ 2) is associated with:[5]
    • ↓ mortality (3%)
    • ↓ need for mechanical ventilation (5%)
    • ↓ length of hospital stay (1d)

Community Acquired (Non-ICU)

Coverage against community acquired organisms plus M. catarrhalis, Klebsiella, S. aureus

Hospital Acquired or Ventilator Associated Pneumonia

Ventilator Associated Pneumnoia

  • High Risk of MRSA: Use 3-Drug Regimen. Several options are available, but recommendation is to include an antibiotic from each of these categories:[7]

ICU, low risk of pseudomonas

ICU, risk of pseudomonas


  • Antibiotics do not help with severity or duration but may decrease infectivity.
  • A reasonable guideline is to treat persons aged >1 year within 3 weeks of cough onset and infants aged <1 year and pregnant women (especially near term) within 6 weeks of cough onset. [8]
  • TMP--SMZ should not be administered to pregnant women, nursing mothers, or infants aged <2 months.[9]
  • The following regemins are for active disease or postexposure prophylaxis. If a patient is has confirmed disease and is likely to be in contact with infants or pregnant women then the patient should be treated as up to 6-8 weeks after the onset of their illness.

< 1 month old

Same antibiotics for active disease and postexposure prophylaxis

>1 month old

  • Azithromycin 10mg/kg (max 500mg/day) daily x 5 days
    • if > 6 months old then day 2-5 of treatment should be reduced to 5mg/kg (250mg/day max)
  • TMP/SMX 4mg/kg PO BID daily for 14 days (if > 2 months old)


any of the following antibiotics are acceptable although azithromycin is most commonly prescribed

See Also

Antibiotics by diagnosis

For antibiotics by organism see Microbiology (Main)


  1. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67
  2. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67
  3. IDSA. Mandell 2007
  4. Chokshi R, Restrepo MI, Weeratunge N, Frei CR, Anzueto A, Mortensen EM. Monotherapy versus combination antibiotic therapy for patients with bacteremic Streptococcus pneumoniae community-acquired pneumonia. Eur J Clin Microbiol Infect Dis. Jul 2007;26(7):447-51
  5. Siemieniuk RA, Meade MO, Alonso-Coello P, Briel M, Evaniew N, Prasad M, Alexander PE, Fei Y, Vandvik PO, Loeb M, Guyatt GH. Corticosteroid Therapy for Patients Hospitalized With Community-Acquired Pneumonia: A Systematic Review and Meta-analysis. Ann Intern Med. Aug 11, 2015
  6. Luther MK, Timbrook TT, Caffrey AR, Dosa D, Lodise TP, LaPlante KL. Vancomycin Plus Piperacillin-Tazobactam and Acute Kidney Injury in Adults: A Systematic Review and Meta-Analysis. Crit Care Med. 2018;46(1):12-20.
  7. Kalil AC, Metersky ML, Klompas M et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016 Sep 1;63(5):e61-e111.
  8. CDC - Pertussis http://www.cdc.gov/pertussis/clinical/treatment.html
  9. CDC MMWR Pertusis http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5414a1.htm