Written by Sam Parnell
Topical antibiotic use for bacterial conjunctivitis was associated with improved rate of clinical cure compared to placebo. For early and late clinical cure with topical antibiotics, the NNT was 9 and 11, respectively.
Why does this matter?
Conjunctivitis is a common complaint encountered in the primary care, urgent care, and emergency care settings. The etiology of conjunctivitis can be bacterial, viral, allergic, or inflammatory, and the exact cause can be difficult to determine. Bacterial conjunctivitis is a clinical diagnosis, and although most cases of bacterial conjunctivitis are self-limiting, topical antibiotics are thought to shorten time to recovery, decrease sight-threatening complications, and reduce the rate of relapse.
Antibiotics speed recovery for conjunctivitis, can’t you see?
This review, which was an update of a 2006 Cochrane review, included 11 randomized controlled trials with a total of 3,673 patients with bacterial conjunctivitis diagnosed either clinically or microbiologically. Topical antibiotics were associated with improved early (2-5 day) clinical cure - RR 1.36 (95% CI 1.15-1.61) and microbiological cure - RR 1.55 (95% CI 1.37-1.76). At 6 to 10 days, topical antibiotics also had clinical benefit - clinical cure: RR 1.21 (95% CI 1.10-1.33) and microbiological cure: RR 1.37 (95% CI 1.24-1.52). The absolute risk difference for early and late clinical cure with topical antibiotics was 11% and 9%, respectively, corresponding to an NNT of 9 and 11. No serious outcomes were reported in the placebo or treatment groups.
Of note, there were significant limitations for many of the studies in this review. The included studies did not have a single standard diagnostic criterion for bacterial conjunctivitis. Also, they used different antibiotic regimens, and many of the included trials were poor quality, with 9 out of 11 trials deemed to have high risk of bias. In addition, no recommendations were made about antibiotic selection or duration.
Nevertheless, though the available evidence is modest, this review shows topical antibiotics are associated with improved cure rates for bacterial conjunctivitis with minimal risk of adverse events.
Topical Antibiotics for Clinical and Microbiological Cure of Bacterial Conjunctivitis. Acad Emerg Med. 2018 Nov 12. doi: 10.1111/acem.13663. [Epub ahead of print]
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Reviewed by Clay Smith