Quinolone-resistant Neisseria gonorrhoeae in Hong Kong

To study the serologic characters and antibiotic susceptibilities of quinolone-resistant Neisseria gonorrhoeae in Hong Kong.

Sixty-nine strains of Neisseria gonorrhoeae isolated from clinical failure cases after treatment with ofloxacin during the period January 1, 1992, to January 1, 1995, were studied. A panel of 14 monoclonal antibodies against protein I classified these strains into 21 serovars. The pattern of serovar distribution against varying minimum inhibitory concentrations of ofloxacin was compared with 143 strains isolated from a cohort of quinolone-susceptible, clinically responsive cases. Antibiotic susceptibilities tests were performed on quinolone-resistant strains to penicillin, tetracycline, ciprofloxacin, spectinomycin, and ceftriaxone. Epidemiologic information on location of contact was collected.

Serologic characterization showed that Bop and Bpy were the dominant serovars among quinolone-resistant strains. Most IA and other IB serovars had declined in the selection process for quinolone resistance. Antibiotic susceptibility tests showed that 81.2%, 89.9%, and 78.3% of quinolone-resistant Neisseria gonorrhoeae strains were resistant to penicillin, tetracycline, and both, respectively, whereas 10 of 69 (14.5%) of such strains displayed high-level quinolone resistance (ofloxacin minimum inhibitory concentration > 8 micrograms/ml). The quinolone-resistant strains remained fully susceptible to spectinomycin and ceftriaxone.

Quinolone-resistant strains have become firmly established in Hong Kong. Serovar determination has documented shifts in the gonococcal population during the selection process for quinolone resistance. Places that use quinolones in the treatment of sexually transmitted diseases should be alert to the emergence of high-level quinolone-resistant Neisseria gonorrhoeae.