Sensitivity pattern of Neisseria gonorrhoeae to penicillin and screening for beta-lactamase production in Ibadan, Nigeria

Abstract

The few reports from Africa on sensitivity determinations of Neisseria gonorrhoeae suggest that there is an increasing resistance in the strains, as has been found in other parts of the world. In the current study, the penicillin sensitivities and β-lactamase production of 80 consecutive strains of N. gonorrhoeae isolated from cases of acute urethritis in African men in Ibadan were studied. Of these strains, 17·5% had a penicillin minimum inhibitory concentration (MIC) of 0·038 μg/ml or less and were considered as being `fully sensitive'. However, 82·5% had an MIC of 0·075 μg penicillin/ml or more, and were considered as having `diminished sensitivity' to penicillin. It was thought that this high incidence of relatively insensitive strains was owing to the sequential selection of these strains because of the easy availability and abuse of antimicrobial agents by the general population. Furthermore, 13 strains (16·25%) demonstrated high level resistance with MIC values of over 0·6 μg penicillin per ml and it is probable that many of the strains will demonstrate multiresistance to the commonly misused antimicrobial agents. Consequently, treatment of patients harbouring these strains may present problems because of financial constraints of the health services in purchasing the appropriate antibiotics. Despite the high level resistance of the strains in an environment of intensive penicillin and ampicillin use, none of the strains studied showed any evidence of β-lactamase production. Nevertheless, continuous surveillance of β-lactamase production by the gonococcus is recommended in the larger medical centres in developing countries.