Commentary

Acute bacterial conjunctivitis is a common minor illness. It is self limiting but is usually treated pragmatically with topical antibiotics in an attempt to shorten the illness and reduce complications and infectivity. Eye swabs are rarely done in clinical practice because of time considerations and expense. Discrimination of bacterial from viral conjunctivitis on clinical grounds is difficult: 50% of cases of presumed bacterial conjunctivitis diagnosed clinically by ophthalmologists in 1 study did not have an underlying bacterial cause on culture.¹

Recently, clinicians have been encouraged to reduce the prescribing of antibiotics for other minor self limiting illnesses (ie, sore throat and otitis media) because of problems with antibiotic resistance.

The review by Sheikh and Hurwitz used rigorous methods to summarise the limited evidence on acute bacterial conjunctivitis. The trials are from secondary care and thus may not be directly applicable to primary care settings. All the trials used microbiologically confirmed cases, which means that the number needed to treat using clinical diagnosis of patients will probably be substantially higher.

Although the review shows improved clinical and microbiological remission rates with antibiotics, it must be remembered that this condition is self limiting. Symptoms are usually mild, and the review shows that 64% of patients are cured at day 2 to 5 without treatment. No serious adverse effects were seen in these studies, which suggests that sight-threatening complications are rare. The effect of a quicker cure in reducing secondary cases of conjunctivitis has not been assessed.

Further trials are needed to clarify whether it is appropriate to prescribe antibiotics for all patients to achieve a few days of reduction in symptoms in a minority of patients. In the meantime, as discussed by the authors, it might be worth considering a delayed prescription strategy (ie, prescribing only for those cases that have not resolved by day 5).