Meta-analysis compares oral antibiotic regimens for mild to moderate CAP

A meta-analysis found a better clinical response and lower mortality for quinolones as empiric antibiotics for community-acquired pneumonia (CAP) but no conclusive evidence of any one antibiotic being more effective than another.

To compare the effects of different empiric oral antibiotic regimens in adults with mild to moderate CAP, researchers did a systematic review and meta-analysis of 24 randomized trials with 9,361 patients: six at low risk of bias, six at unclear risk, and 12 at high risk. Results were published by the Journal of General Internal Medicine on Feb. 15.

The review found that nemonoxacin, levofloxacin, and telithromycin were most likely to achieve clinical response (p-scores, 0.79, 0.71, and 0.69, respectively), while penicillin and amoxicillin were the least likely. Levofloxacin, nemonoxacin, azithromycin, and amoxicillin-clavulanate were most likely to be associated with lower mortality (p-scores, 0.85, 0.75, 0.74, and 0.68, respectively). Sparfloxacin was least likely to reduce mortality.

Quinolones and macrolides were the antibiotic classes that were most effective for clinical response (p-scores, 0.71 and 0.70, respectively), while amoxicillin-clavulanate plus macrolides (p-score, 0.11) and beta-lactams were less effective (p-score, 0.22). Quinolones were most likely to be associated with lower mortality (p-score, 0.63). However, the researchers noted that all confidence intervals were broad and partially overlapping.

There was a trend for a worse clinical response for beta-lactams and the combination of amoxicillin-clavulanate and a macrolide. "The latter is notable because it is recommended by several practice guidelines as a preferred choice," the study authors wrote.

More trials are needed to inform guideline recommendations on the most effective antibiotic regimens for outpatients with mild to moderate CAP, they said. Also, while doxycycline is recommended as a first-line option by the Infectious Diseases Society of America/American Thoracic Society guidelines, no study that included doxycycline met inclusion criteria for the meta-analysis.

"While our results suggest favoring nemonoxacin, levofloxacin, telithromycin, and clarithromycin over penicillin and amoxicillin, these results are limited by lack of statistical significance and the relatively small number of studies making direct comparisons of these drugs," the authors wrote.