Failure of ciprofloxacin to eradicate convalescent fecal excretion after acute salmonellosis: experience during an outbreak in health care workers.

OBJECTIVE

To determine the efficacy of ciprofloxacin therapy in eradicating convalescent fecal excretion of salmonellae after acute salmonellosis.

DESIGN

Randomized, placebo-controlled, double-blind trial of ciprofloxacin, with prospective follow-up of nonparticipants.

SETTING

An acute care community hospital experiencing an outbreak of salmonellosis.

PATIENTS

Twenty-eight health care workers developed acute infection with Salmonella java; 15 participated in a placebo-controlled trial of ciprofloxacin, beginning on day 9 after infection.

INTERVENTIONS

Eight patients were randomly assigned to receive ciprofloxacin, 750 mg, and 7 patients to receive placebo; both were administered orally twice daily for 14 days. Nonparticipants who received therapy were placed on the same ciprofloxacin regimen.

MEASUREMENTS AND MAIN RESULTS

Study participants had follow-up stool cultures every 3 days initially and then weekly for 3 weeks; nonparticipants were followed until three consecutive cultures were negative. All eight ciprofloxacin recipients showed eradication of S. java from stool cultures within 7 days of beginning therapy (compared with 1 of 7 placebo recipients), and their stool cultures remained negative up to 14 days after discontinuing therapy (P less than 0.01). However, 4 of 8 relapsed; their stool cultures became positive between 14 and 21 days after therapy. In addition, 3 of 3 hospitalized patients treated with ciprofloxacin who did not participate in the controlled trial also relapsed. Thus, the total relapse rate was 7 of 11 (64%; 95% CI, 31% to 89%). In 4 of these 7 patients, relapse was associated with a longer duration of fecal excretion of salmonellae than that of the placebo group. Relapse could not be explained on the basis of noncompliance, development of resistance, or presence of biliary disease.

CONCLUSIONS

Despite its excellent antimicrobial activity against salmonellae and its favorable pharmacokinetic profile, ciprofloxacin at a dosage of 750 mg orally twice daily had an unacceptably high failure rate in patients with acute salmonellosis and may have prolonged fecal excretion of salmonellae. The late occurrence of relapses indicates the need to obtain stool cultures up to 21 days after therapy to document fecal eradication in acute salmonellosis.