Neisseria gonorrhoeae isolates from Ethiopia 1. In vitro susceptibility patterns to five antibiotics.

Five hundred Neisseria gonorrhoeae strains isolated between January 1977 and February 1978 from male patients in Addis Ababa were tested by the agar dilution technique for their susceptibility to penicillin, ampicillin, tetracycline, chloramphenicol, and streptomycin.The minimal inhibitory concentration (MIC) values of penicillin and ampicillin for the isolates varied from </=0.005 to 1.28 mg/litre and from </=0.025 to 0.8 mg/litre respectively. The tetracycline values ranged from </=0.2 to 3.2 mg/litre and those of chloramphenicol from </=0.125 to 8.0 mg/litre. Streptomycin concentrations of 10, 20, 40, 50, 100, and 200 mg/litre each inhibited growth of a number of strains. 107 strains (21.4%) were not inhibited, even by a concentration of 200 mg/litre, the highest employed.Forty-one percent of strains were resistant to penicillin, requiring 0.08 mg/litre or a higher concentration for inhibition, and 58.4% were resistant to ampicillin, inhibition occurring only at concentrations >/=0.2 mg/litre. The percentage of strains resistant to penicillin was significantly lower than that reported 7 years ago (50%). Resistance to tetracycline was shown in 8.2% of strains. None of the 500 strains showed resistance to chloramphenicol. Streptomycin resistance was detected in 43.8% of the strains.