Antimicrobial susceptibility of Neisseria gonorrhoeae in Harare, Zimbabwe. Relationship to serogroup.

The authors investigated one hundred fifty-four isolates of Neisseria gonorrhoeae obtained from men, women, and infants in Harare, Zimbabwe, for in vitro susceptibility to various antibiotics and for reactivity with serogrouping antisera. The authors found sixty-four (42%) isolates to be WI serogroup and 90 (58%) to be WII/III. One hundred three isolates were penicillinase-producing N. gonorrhoeae (PPNG); although all of these showed resistance to penicillin, 14 isolates had an MIC to penicillin of less than 10 mg/L. All of these 14 isolates were WI serogroup. Twenty-seven of the 51 non-PPNG showed in vitro resistance to penicillin (MIC greater than 1.25 mg/L). All but one of these chromosomally resistant isolates were WII/III serogroup. With cefuroxime, tetracycline, and erythromycin, 10-15% of isolates had MICs greater than accepted breakpoints. Most isolates were susceptible to thiamphenicol, and all were susceptible to ciprofloxacin, kanamycin, and spectinomycin. The authors noted that WI isolates, whether PPNG or not, were consistently more susceptible to antibiotics than WII/III isolates. Only with kanamycin and spectinomycin were the MICs of the two serogroups similar.