Evolution in the trends of antimicrobial resistance in Neisseria gonorrhoeae isolated in Durban over a 5 year period: impact of the introduction of syndromic management.

Antimicrobial susceptibility testing was performed on isolates of Neisseria gonorrhoeae obtained from patients attending the City Health STD clinic in Durban, KwaZuluNatal, using the following drugs: penicillin, tetracycline, ciprofloxacin, ofloxacin, ceftriaxone, spectinomycin, erythromycin and azithromycin. These isolates were collected over a 6 year period from 1995 to 2000. Four hundred and fifteen strains were tested: 61 in 1995, 198 in 1997, 98 in 1998/99 and 58 in 1999/2000. A shift to the right is observed in the susceptibilities of N. gonorrhoeae to the currently recommended drugs in the syndromic management guidelines viz. penicillin, tetracycline, ceftriaxone, ciprofloxacin, spectinomycin and erythromycin. The prevalence of penicillinase-producing N. gonorrhoeae is currently c. 30%, whereas that of plasmid-mediated tetracycline-resistant N. gonorrhoeae is c. 50%. There is a definite association between the MICs of strains falling within the penicillin and tetracycline chromosomally resistant group, and strains exhibiting a decreased susceptibility to ciprofloxacin and ceftriaxone. The MICs of azithromycin showed a similar distribution when compared with erythromycin for 1999/2000 isolates. We postulate that the presence of efflux pumps might play a role in the increasing MICs that we observe among structurally unrelated groups of drugs. Furthermore, widespread use of these antimicrobials in the community may offer a selective advantage to the development of resistance. The implications of this are far reaching and the local susceptibility trends of N. gonorrhoeae need to be monitored constantly to direct therapy.