Trimethoprim/sulfamethoxazole is currently considered the treatment of choice for
shigellosis and severe travelers'
diarrhea. The problem with this combination regimen is inactivity against Campylobacter jejuni strains and other bacterial enteropathogens showing in vitro resistance to the
drug. Resistance to
trimethoprim/sulfamethoxazole among enteric pathogens has occurred frequently in certain areas of the world. A study of the in vitro susceptibility of enteric bacterial pathogens isolated from multiple countries was recently performed. The minimal inhibitory concentration of
ciprofloxacin required to inhibit 90 percent of the 210 bacterial enteropathogens ranged from 0.25 micrograms/ml for C. jejuni to 0.016 micrograms/ml for enterotoxigenic Escherichia coli, Salmonella, and Shigella. In a clinical trial carried out in a United States student population that acquired
diarrhea while in Mexico, it was shown that
ciprofloxacin was as effective as
trimethoprim/sulfamethoxazole and both were significantly (p less than 0.001) more effective than placebo. The average duration of
diarrhea was 29 or 20 hours after initiation of treatment with
ciprofloxacin or
trimethoprim/sulfamethoxazole, respectively, compared with 81 hours in the placebo group. The
antimicrobial agents were more efficacious than placebo in treating
diarrhea caused by enterotoxigenic E. coli, invasive enteropathogens, and unknown pathogens.
Ciprofloxacin and the
quinolone derivatives are uniquely suited to the
therapy of acute bacterial
diarrhea in areas where C. jejuni is commonly found and where
trimethoprim/sulfamethoxazole-resistant strains regularly occur.