Comparative in vitro activities of aztreonam, ciprofloxacin, norfloxacin, ofloxacin, HR 810 (a new cephalosporin), RU28965 (a new macrolide), and other agents against enteropathogens.

The in vitro activity of drugs currently used in the treatment of diarrhea against 595 enteropathogens from worldwide sources was compared with that of six newly developed antibiotics, ciprofloxacin; norfloxacin; ofloxacin; aztreonam; HR810, an expanded-spectrum cephalosporin; and RU28965, a new macrolide. In contrast with ampicillin and chloramphenicol, trimethoprim-sulfamethoxazole showed an excellent activity against all of the enteropathogens tested, except Campylobacter species. Ciprofloxacin had the highest activity, with an overall 90% MIC of less than or equal to 0.097 micrograms/ml, except for Campylobacter species (0.39 micrograms/ml). Unlike other cephalosporins, HR810 showed a satisfactory activity against Campylobacter species (90% MIC of 3.12 micrograms/ml). RU28965 was three times less active than erythromycin against Campylobacter species.