Abstract: Objective To investigate the resistant status and to type the phenotype and plasmid profiles of prevalent gonococcal strains. Methods A total of 98 gonococcal strains isolated from 1998 to 1999 in Zhanjiang was identified systemically. The susceptibilities of 98 strains of gonococci to penicillin,tetracycline and ciprofloxacin were detected by agar dilution method. The β-lactamase production was tested by iodometric method. The plasmids were extracted by alkaline lysis technique. Results The prevalence of gonococcal strains resistant to penicillin, tetracycline and ciprofloxacin were 22.44%,45.94% and 55.12%,respectively. There were 6 positive strains forβ-lactamase, accounting for 6.12% (6/98). The most common phenotypes were susceptible^PT、CMRNG^T、CMRNG^PT and TRNG, accounting for 43.86%,23.46%,10.20% and 10.20%,respectively. The detection rate of plasmids were 91.84%.Among them, the percentages of 42.5 kb,39.5 kb,7.4 kb and 4.2 kb plasmids accounted for 11.22%,41.82%,59.16% and 67.32%,respectively.There were 12 types of plasmid profiles(PP), the predominant types were 7.4kb+4.2kb and 39.5kb+7.4kb+4.2kb, accounting for 21.42% and 17.34%,respectively. Conclusion The gonococcal strains resistant to ciprofloxacin are very high in Zhanjiang. The phenotype and plasmid profiles of the strains have characteristic distribution.

Key words: Plasmids, Neisseria gonorrhoeae, Microbial sensitivity tests