November 5, 2014
Review: Limit Antibiotic Treatment in Community
Acquired Pneumonia  

Houston—Initial antibiotic therapy for community-acquired pneumonia should be limited to 5 to 7 days for outpatients and even for inpatients if they have a prompt response to therapy.

That’s according to a review article on pneumonia published recently in the New England Journal of Medicine.

Early in the antibiotic era, pneumonia was treated for about 5 or fewer days, according to the article, written by Daniel M. Musher MD, of the Michael E. DeBakey Veterans Affairs Medical Center, and Baylor College of Medicine, both in Houston, and Anna R. Thorner, MD, of Brigham and Women’s Hospital and Harvard Medical School, both in Boston. In fact, they point out, “some studies even showed that a single dose of penicillin G procaine was curative.”

“The standard duration of treatment later evolved to 5 to 7 days. A meta-analysis of studies comparing treatment durations of 7 days or less with durations of 8 days or more showed no differences in outcomes, and prospective studies have shown that 5 days of therapy are as effective as 10 days, and 3 days are as effective as 8,” Musher and Thorner write. “Nevertheless, practitioners have gradually increased the duration of treatment for CAP to 10 to 14 days. A responsible approach to balancing antibiotic stewardship with concern about insufficient antibiotic therapy would be to limit treatment to 5 to 7 days, especially in outpatients, or in inpatients who have a prompt response to therapy.”

The authors point out that clinicians often choose to use the longer therapy because of concerns about small abscesses caused by Staphylococcus aureus (S. aureus) or gram-negative bacilli.

“Hematogenous Staph. aureus pneumonia mandates treatment for at least 4 weeks, but segmental or lobar pneumonia that is caused by this organism may be treated for 2 weeks,” according to the review. “Cavitating pneumonia and lung abscesses are usually treated for several weeks; some experts continue treatment until cavities have resolved. The lack of a response to seemingly appropriate treatment in a patient with CAP should lead to a complete reappraisal, rather than simply to selection of alternative antibiotics.”

The authors emphasize that pneumonia should be treated on an outpatient basis only after a careful assessment of need for hospitalization and where follow-up contact is assured.

Noting that the use of quinolones is typically reserved for outpatients with substantial coexisting illnesses or recent use of antibiotics from another class, review authors recommend the following therapy selections for pneumonia treated outside of the hospital:

• For syndromes suggesting typical bacterial pneumonia: amoxicillin–clavulanate with the addition of azithromycin if legionella species are a consideration; levofloxacin or moxifloxacin may be used instead
• For syndromes suggesting influenza pneumonia: oseltamivir with observation for secondary bacterial infection
• For syndromes suggesting viral pneumonia other than influenza: symptomatic therapy
• For syndromes suggesting mycoplasma or chlamydophila pneumonia: azithromycin or doxycycline
As for inpatient treatment, Musher and Thorner make the following suggestions based on evidence-based studies:
• For initial empirical therapy: a beta-lactam (ceftriaxone, cefotaxime, or ceftaroline) plus azithromycin; levofloxacin or moxifloxacin may be used instead
• If influenza is likely: oseltamivir
• If influenza is complicated by secondary bacterial pneumonia: ceftriaxone or cefotaxime plus either vancomycin or linezolid, in addition to oseltamivir
• If S. aureus is likely: vancomycin or linezolid in addition to the antibacterial regimen
• If pseudomonas pneumonia is likely: antipseudomonal beta-lactam (piperacillin–tazobactam, cefepime, meropenem, or imipenem–cilastatin) plus azithromycin

The review also discusses some “important unresolved problems” remaining with CAP, including that no causative organism is identified in half of patients.

“It is unclear what proportion of these cases are attributable to infection by so-called typical or atypical bacterial pathogens, oral flora, viruses, or other pathogens,” according to the study authors, who add that increased use of polymerase chain reaction (PCR) testing will determine the frequency with which legionella, chlamydophila, and mycoplasma species, along with other pathogens, cause CAP.

“It remains to be determined whether the availability of sensitive diagnostic tests such as PCR will increase the use of targeted therapies and reduce dependence on empirical antibiotic therapy,” the review concludes. “Increasing antibiotic resistance in bacteria may compound the difficulty of selecting an effective regimen. Randomized trials are needed to determine whether the anti-inflammatory activity of macrolides or statins is beneficial in treating CAP.”

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