Penicillin and tetracycline susceptibility of gonococci from Addis Ababa and incidence of penicillinase-producing strains.

One hundred and nine Neisseria gonorrhoeae strains were isolated from urethral discharge of male patients in a health centre in Addis Ababa, identified following conventional procedures, and tested for penicillin and tetracycline susceptibility by the agar dilution technique. World Health Organization reference strains were also tested as controls. Penicillinase producing N. gonorrhoeae (PPNG) were identified using Oxoid beta-lactamase detection papers. Minimal inhibitory concentration (MIC) values of penicillin varied between less than 0.01 mg l-1 and greater than 10.24 mg l-1 while those of tetracycline, between less than 0.25 mg l-1 and 4.0 mg l-1. About 64% of isolates were resistant to penicillin, requiring MICs of greater than or equal to 0.64 mg l-1: 26% were resistant to tetracycline, requiring greater than or equal to 2 mg l-1 for inhibition. The rate of simultaneous resistance to both antibiotics was 18%. PPNG comprised 49% of isolates, of which 23% were resistant also to tetracycline. Of 70 penicillin-resistant strains, 17 (24%) were non-PPNG.