Susceptibilities of Hong Kong isolates of multiply resistant Shigella spp. to 25 antimicrobial agents, including ampicillin plus sulbactam and new 4-quinolones.

Seventy-two percent of 129 shigella isolates from two Hong Kong hospitals were Shigella flexneri. Twenty-six percent were S. sonnei, and there was only one isolate each of S. dysenteriae and S. boydii. Ninety-six percent of the isolates were resistant to two or more antibiotics, and up to 11 resistances were seen in a single isolate. Fifty-seven percent or more of these isolates were resistant to ampicillin, streptomycin, tetracycline, chloramphenicol, and sulfamethoxazole; and up to twenty-three percent were resistant to kanamycin, trimethoprim, trimethoprim-sulfamethoxazole, and gentamicin. All the isolates were susceptible to amikacin, nalidixic acid, and the newer 4-quinolone agents; and all but one were susceptible to the cephalosporins tested. Only three isolates remained resistant to ampicillin in the presence of sulbactam. Ampicillin plus sulbactam or the newer 4-quinolone agents may be alternatives for the treatment of severe infections caused by multiply resistant shigellas.