Oral aztreonam, a poorly absorbed yet effective therapy for bacterial diarrhea in US travelers to Mexico.

Objective: To evaluate a poorly absorbed antimicrobial with in vitro activity against all major bacterial enteropathogens in oral therapy for bacterial diarrhea.

Design: One hundred ninety-one US students with diarrhea acquired in Mexico received 100 mg of aztreonam or matching placebo three times a day for 5 days. Stools were cultured for bacterial enteropathogens before and after therapy.

Setting: We studied US students who acquired diarrhea in Mexico (travelers' diarrhea) in view of the high frequency of bacterial agents in this setting.

Main Outcome Measure: We examined time of clinical recovery, treatment failures, adverse experiences, and microbiologic eradication from stool of the etiologic agent in subjects randomized to receive aztreonam or placebo.

Results: Aztreonam reduced the average duration of diarrhea compared with the placebo: for all cases, by 40 hours (P much less than .01); for those with enterotoxigenic Escherichia coli diarrhea, by 50 hours (P less than .01); for those with shigellosis, by 90 hours (P, not significant [small sample size]); for all bacterial agents, by 57 hours (P much less than .01). Clinical failures during the 5 days of therapy were seen in six patients (6%) receiving aztreonam and 25 (27%) receiving placebo (P less than .01). Pathogen eradication occurred in 95% of those receiving aztreonam and in 70% of those receiving the placebo (P less than .01). All bacterial enteropathogens were susceptible in vitro to aztreonam. The drug was well tolerated.

Conclusions: Oral aztreonam, which is poorly absorbed, was well tolerated and was an effective therapy for bacterial diarrhea in US adults in Mexico.