Clinical failure with and without empiric atypical bacteria coverage in hospitalized adults with community-acquired pneumonia: a systematic review and meta-analysis

Background: Both typical and atypical bacteria can cause community-acquired pneumonia (CAP); however, the need for empiric atypical coverage remains controversial. Our objective was to evaluate the impact of antibiotic regimens with atypical coverage (a fluoroquinolone or combination of a macrolide/doxycycline with a β-lactam) to a regimen without atypical antibiotic coverage (β-lactam monotherapy) on rates of clinical failure (primary endpoint), mortality, bacteriologic failure, and adverse events, (secondary endpoints).

Methods: We searched the PubMed, EMBASE and Cochrane Library databases for relevant RCTs of hospitalized CAP adults. We estimated risk ratios (RRs) with 95% confidence intervals (CIs) using a fixed-effect model, but used a random-effects model if significant heterogeneity (I ² ) was observed.

Results: Five RCTs with a total of 2011 patients were retained. A statistically significant lower clinical failure rate was observed with empiric atypical coverage (RR, 0.851 [95% CI, 0.732-0.99; P = 0.037]; I ² = 0%). The secondary outcomes did not differ between the two study groups: mortality (RR = 0.549 [95% CI, 0.259-1.165, P = 0.118], I ² = 61.434%) bacteriologic failure (RR = 0.816 [95% CI, 0.523-1.272, P = 0.369], I ² = 0%), diarrhea (RR = 0.746 [95% CI, 0.311-1.790, P = 0.512], I ² = 65.048%), and adverse events requiring antibiotic discontinuation (RR = 0.83 [95% CI, 0.542-1.270, P = 0.39], I ² = 0%).

Conclusions: Empiric atypical coverage was associated with a significant reduction in clinical failure in hospitalized adults with CAP. Reduction in mortality, bacterial failure, diarrhea, and discontinuation due to adverse effects were not significantly different between groups, but all estimates favored atypical coverage. Our findings provide support for the current guidelines recommendations to include empiric atypical coverage.