What is the optimal duration of antibiotic therapy?

Jun 8 2006

Taking antibiotics for three days is just as effective for community acquired pneumonia as continuing treatment for the recommended 7-10 days, finds a study in this week's British Medical Journal.

Shorter treatment can also help contain growing resistance rates.

The study raises questions about the optimal duration of antibiotic therapy for common infections.

Community acquired pneumonia is one of the most important indications for antibiotic prescriptions in hospitals. But a lack of evidence to support short course therapy means it has become accepted practice to continue treatment for days after symptoms have improved.

Researchers in the Netherlands compared the effectiveness of discontinuing treatment with amoxicillin after three days or eight days in adults admitted to hospital with mild to moderate-severe community acquired pneumonia.

119 patients who substantially improved after the conventional three days' treatment with intravenous amoxicillin were randomly assigned to oral amoxicillin (63 patients) or placebo (56 patients) three times daily for five days. Patients were assessed at days 7, 10 (two days after treatment ended), 14, and 28.

In the three day and eight day treatment groups, the clinical success rate at day 10 was 93% for both, and at day 28 was 90% compared with 88%. Both groups had similar resolution of symptoms, x-ray results, and length of hospital stay.

These findings show that discontinuing amoxicillin treatment after three days is not inferior to discontinuing it after eight days in adults with mild to moderate-severe community acquired pneumonia who have substantially improved after an initial three days' treatment, say the authors.

A shorter duration of treatment can also help to reduce overall antibiotic consumption and resistance rates for respiratory infections, they conclude.

This study suggests that current guidelines recommending 7-10 days should be revised, says Dr John Paul from the Royal Sussex County Hospital, in an accompanying commentary.

Not only does the study yield strong evidence in favour of short course therapy for a subset of patients with community acquired pneumonia, but also shows how centres can cooperate to tackle longstanding areas of uncertainty in clinical microbiology and infectious diseases, he writes. Many other common clinical situations would repay the efforts of comparable approaches.