BACKGROUND: Acute conjunctivitis (pinkeye) accounts for 1% to 4% of primary care office visits. Although often viral, common bacterial pathogens include Streptococcus pneumoniae, Haemophilus influenza, and Staphylococcus aureus. Antibiotics are commonly prescribed in the belief that they hasten recovery and reduce complications, although little data are available to support this assertion.
POPULATION STUDIED: The authors of this meta-analysis performed a comprehensive search of MEDLINE, The Cochrane Library, the Cochrane Eyes and Vision Group Register, Science Citation Index, the bibliographies of retrieved reports, and inquiry to authors and pharmaceutical companies producing relevant ophthalmic preparations. They identified 5 randomized controlled trials comparing topical antibiotics with placebo for the treatment of bacterial conjunctivitis. Two trials were excluded because of incomplete blinding or deficient reporting of data. The remaining 3 trials involved 527 patients of various ages (1 studied children only, 1 did not specify, and 1 studied adults) treated with: (1) polymyxin and bacitracin, (2) ciprofloxacin or tobramycin, or (3) norfloxacin.
STUDY DESIGN AND VALIDITY: Two authors determined whether studies met inclusion criteria and graded eligible studies for quality. Relative benefit (relative risk of clinical or microbial remission) was calculated using Review Manager software (Cochrane Collaboration).The 3 included studies were not homogeneous in their populations studied (children vs adults), the method of diagnosis (culture vs clinical assessment), and the outcomes measured (clinical vs microbiologic resolution, time to resolution measured). However, the results of the 3 studies were statistically homogenous, supporting the combination of the results by meta-analysis. The criteria used to make clinical assessments for inclusion or for evaluating outcomes are not discussed, making it difficult to assess their validity. In 1 study, data were combined from of 2 trials, 1 comparing the use of ciprofloxacin with placebo, and the other comparing ciprofloxacin with tobramycin. Details about the nature of the allocation process for this study are lacking, but exclusion of this study does not significantly change the results. The greatest limitation of this study is its applicability to the primary care setting. The majority of the patients come from hospital-based clinics, and 2 of the 3 studies used subjects with culture-confirmed bacterial conjunctivitis, while most patients in primary care are treated empirically without culture confirmation.
OUTCOMES MEASURED: Outcomes included clinical cure (not otherwise described) or microbiologic cure (by culture) at 2 time frames: early (2-5 days) and late (6-10 days). One of the 3 studies measured microbiologic remission only at day 3. results By clinical cure, conjunctivitis was resolved by day 2 to 5 in 64% of patients using placebo and in 83% of those using topical antibiotics (relative risk [RR]=1.31; 95% confidence interval [CI], 1.11-1.55; number needed to treat [NNT]=5.3). This relative benefit was not statistically significant after 5 days (RR=1.27; 95% CI, 1.00-1.61) in the 1 study providing evaluation at this time. The relative benefit was also smaller in the study that used clinical assessment to diagnose bacterial infection (RR=1.31; 95% CI, 1.11-1.55; NNT=6.25). Microbiologic remission was also more often attained in the patients receiving antibiotics than in those on placebo, with a relative benefit of 1.71 (95% CI, 1.32-2.21), which remained stable at 6 to 10 days as well. No serious adverse reactions were reported in either the treatment groups or the placebo groups.
Topical antibiotics can reduce the time to clinical and microbiologic remission in patients with bacterial conjunctivitis, particularly with culture-proven infection. However, the majority of patients experience clinical resolution of the condition without treatment. Further, as many cases of conjunctivitis in a primary care clinic are viral in origin,1 the efficacy of antibiotics is likely to be lower in practice than in this study. Antibiotics should be reserved for patients in whom bacterial infection is strongly suspected. Bacterial infection is more likely to present with an abrupt onset of ocular irritation, diffuse hyperemia, and purulent drainage that mats the eyelids at wakening. Viral conjunctivitis is characterized by a watery or mucoid discharge and often a history of a viral upper respiratory infection. Viral infection is also suggested in the case of rapid spread in families, daycare, or school settings, as it is highly contagious even up to 2 weeks after the onset of symptoms.