Antimicrobial resistance in gonococci isolated from patients and from commercial sex workers in Harare, Zimbabwe

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Abstract

The objective is to compare antibiotic resistance amongst gonococci isolated from different patient groups in Harare, Zimbabwe. Antimicrobial susceptibilities of Neisseria. gonorrhoeae were determined by disc sensitivity tests. The MICs for penicillin, kanamycin, ceftriaxone, norfloxacin and ciprofloxacin were determined using E-test strips. There were 147 isolates from symptomatic men, 47 isolates from symptomatic women, 29 isolates from asymptomatic women and 41 isolates from female commercial sex workers. A total of 119 (45%) isolates were PPNG and 23 (16%) non-PPNG isolates had a penicillin MIC>0.64 mg/l. Over 90% of isolates were resistant to TMP/SMX and 16% were resistant to tetracycline. Resistance was uncommon against kanamycin (6%), erythromycin (2%) or ceftriaxone (<1%). For kanamycin, the MIC90 was 32 mg/l, for ceftriaxone the MIC90 was <0.032 mg/l for non-PPNG and <0.064 mg/l for PPNG. For norfloxacin and ciprofloxacin the MIC90 was <0.064 mg/l for both PPNG and non-PPNG. Isolates from the commercial sex workers showed a significantly increased prevalence of PPNG, of penicillin-tolerant non-PPNG and of tetracycline resistance. Four of the 41 isolates from sex workers showed multiple resistance (to penicillin, TMP/SMX, tetracycline and kanamycin) compared to 1/223 isolates from other groups (OR=24.0). Antimicrobial resistance is common amongst gonococci in Harare, especially with isolates from commercial sex workers. In order for STD treatment to be implemented as an effective strategy in HIV control, continued monitoring of resistance patterns is essential.

Introduction

Prompt and effective treatment of sexually transmitted diseases (STD), coupled with condom promotion, are important strategies in AIDS control in sub-Saharan Africa 1, 2, 3. There is now convincing evidence, from both cross-sectional and cohort studies, that both ulcerative and non-ulcerative STDs are significant co-factors in HIV transmission, with the latter contributing a 3–5-fold increased risk 4, 5. Urethritis and cervicitis are among the most common presenting symptoms in adult outpatients attending primary care clinics in Zimbabwe 6, 7and over 60% of these patients may be HIV seropositive 7, 8. The use of simple algorithms for the syndromic management of genital discharge is an essential feature of programmes for STD and HIV control in this setting.

Strategies for the management of urethritis/cervicitis must include anti-gonococcal therapy, since Neisseria gonorrhoeae is the pathogen most frequently detected in patients with these conditions 6, 7, 8. Previous studies have shown resistance to many antimicrobials amongst isolates of N. gonorrhoeae in Zimbabwe 9, 10and the current recommendation for treatment of gonorrhoea is a single intramuscular dose (2 g) of kanamycin [11]. While there has been some anecdotal evidence of kanamycin treatment failure, gonococcal resistance to this antibiotic has not so far been demonstrated to be widespread.

In order to provide a rational basis for the management of urethral/cervical discharge syndromes, the antimicrobial susceptibilities of 223 isolates of N. gonorrhoeae from symptomatic and asymptomatic men and women in Harare were examined. Due to the fact that commercial sex workers are a significant ‘core group’ for STD and HIV transmission 12, 13, the antimicrobial susceptibilities of 41 isolates from sex workers in Harare were also determined.

Section snippets

Materials and methods

Symptomatic men and women were seen at genitourinary clinics of the city of Harare and of the Zimbabwe AIDS Prevention Project during 1995–1996. The former serve residents of the high-density housing suburbs of Harare and the latter monitors a cohort of 2500 factory workers for HIV and STD incidence. During the course of a clinical examination, urethral/cervical swabs were plated directly onto New York city agar and placed in a candle extinction jar. Asymptomatic pregnant women were seen at

Results

In all, 147 isolates of N. gonorrhoeae were available from symptomatic men, 47 from symptomatic women, 41 from commercial sex workers and 29 from asymptomatic women. Of these 264 isolates, 119 (45%) were PPNG and all of these showed resistance to ampicillin by disc sensitivity. The great majority (244, 92%) of the isolates were resistant to TMP/SMX and resistance to tetracyline was detected in 43 (16%) isolates. Resistance was uncommon against kanamycin (14, 6% isolates), erythromycin (6, 2%

Discussion

Penicillins have not been widely used for the treatment of gonorrhoea in Harare since the early 1980s, when PPNG were first detected and rapidly became predominant amongst the local gonococcal population 16, 17. Reduced clinical cure rates can be expected with strains that have an MIC of 0.5 mg/l or higher [18]and high MICs were characteristic not only of all PPNG but also of almost half the non-PPNG. Even though the addition of clavulanic acid may overcome the resistance mediated through

Acknowledgements

This report is based on data from investigations that were supported by the World Bank, the Royal Netherlands Embassy, the Preparation for AIDS Vaccine Evaluation and Family Health International. We are indebted to the many nursing and laboratory staff who assisted in the collection and processing of specimens, and for the permission of the Director of Health Services, city of Harare for his permission to carry out collections in Municipal Clinics. All studies were approved by the Medical

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