Community-acquired pneumonia

Streptococcus pneumoniae (pneumococcus) is the most serious common cause of pneumonia and empiric therapy must include an antibiotic with predictable activity.

In VIHA 98% of S. pneumoniae isolates are susceptible to amoxicillin in high dose (1g TID). In contrast, 23% of S. pneumoniae isolates are resistant to macrolides and 16% are resistant to doxycycline.

Prior antibiotic use in the last 3 months is a significant consideration in empiric therapy selection. Use of an agent from a different class of antibiotic is highly recommended.


Amoxicillin 1 g PO TID

If concerned about co-morbidities or atypical pathogens


Doxycycline 100 mg PO BID with food
Clarithromycin 500 mg PO BID

Nursing Home

Amox-clavulanate 500 mg PO TID or 875 mg PO BID

Inpatient (Ward)

Ceftriaxone 1 g IV q24h

If concerned about atypical pathogens


Doxycycline 100 mg PO BID with food
Clarithromycin 500 mg PO BID (or Azithromycin 500 mg IV daily if unable to take oral therapy)

Suspected Aspiration

Antimicrobial therapy for the treatment of aspiration without signs and symptoms of infection is usually not indicated. Risk factors for the development of aspiration pneumonia include advanced age, dysphagia, gastric dysmotility, and poor oral hygiene.

Gram-negative and gram-positive organisms represent the majority of pathogens, with anaerobes being rarely involved. Specific anti-anaerobic treatment is not routinely warranted but may be indicated in patients with severe periodontal disease, putrid sputum, or evidence of necrotizing pneumonia or lung abscess on chest X-ray.

Penicillin or Cephalosporin Allergy Alternatives

Penicillin-allergic (rash):

Cefuroxime axetil 500 mg PO BID

Severe pen-allergy or cephalosporin allergy (e.g. anaphylaxis, angioedemia):

Moxifloxacin 400 mg PO daily

  • Moxifloxacin is an effective agent against community-acquired respiratory pathogens (provided no previous fluoroquinolone use in past 3 months), BUT it should be reserved as 3rd-line agent.

Failure or Critical Care setting

Refer to BUGS & DRUGS or consult with Medical Microbiology / Infectious Disease.