Effectiveness of antibiotics in treating cholera reviewed

Cholera is an acute watery diarrhea caused by infection with the bacterium Vibrio cholerae, which can cause rapid dehydration and death. Effective treatment requires early diagnosis and rehydration using oral rehydration salts or intravenous fluids. This review looked at the effects of adding antimicrobial drugs to this treatment.

Thirty-nine randomized and quasi-randomized controlled clinical trials were included in the review, with a combined total of 4623 participants, both adults and children. Overall the researchers found that antimicrobial therapy shortened the average duration of diarrhea by about a day and a half when compared to placebo or no treatment. Antimicrobial therapy also reduced the total stool volume by 50% and reduced the amount of rehydration fluids required by 40%, and shortened the duration of fecal extraction of vibrios bacteria by almost three days.

There was substantial variation between trials in the size of these benefits, probably due to differences in the antibiotic used, the trial methods (particularly effective randomization), and the timing of outcome assessment. However the benefits of antibiotics were seen both in trials recruiting only patients with severe dehydration and in those recruiting patients with mixed levels of dehydration.

In direct head-to-head comparisons, researchers found that there were no obvious differences detected in diarrhea duration or stool volume for tetracycline compared to doxycycline or tetracycline compared to ciprofloxacin or norfloxacin. However, a higher number of studies looked at indirect comparisons and in those cases tetracycline appeared to have larger benefits than doxycycline, norfloxacin and trimethoprim-sulfamethoxazole, while single dose azithromycin shortened the duration of diarrhea by over a day compared to ciprofloxacin and by half a day compared to erythromycin. Tetracycline was not compared with azithromycin.

Ya'ara Leibovici-Weissman from Tel Aviv University said: "In treating cholera a quick and accurate diagnosis remains key, but it is clear from the results that antimicrobials result in substantial improvements in clinical and microbiological outcomes, with similar effects observed in severely and non-severely ill patients. Our results also point to the likelihood that azithromycin and tetracycline may have some advantages over other antibiotics."