Neisseria gonorrhoeae isolates from Ethiopia 2. Pair correlations between minimal inhibitory concentration values of five antibiotics and frequency of multiple antibiotic resistance.

The minimal inhibitory concentration (MIC) values of penicillin, ampicillin, tetracycline, chloramphenicol, and streptomycin for 500 gonococcal strains were studied for product-moment coefficient correlations. The strains were isolated from male patients with acute gonococcal urethritis attending the Venereal Disease Clinic in Addis Ababa.The MICs of all pairs except the ampicillin/streptomycin pair were positively correlated, with r = 0.20-0.53, P<0.001. The ampicillin/streptomycin pair was not correlated, r = 0.06, P>0.05.Despite the significant correlation between the susceptibilities of strains to penicillin and tetracycline, 85% of the penicillin-resistant strains were sensitive to tetracycline. However, 75.6% of tetracycline-resistant strains were also resistant to penicillin. Similar differences in percentages of resistance and susceptibility of strains also occurred between tetracycline and ampicillin as well as between tetracycline and streptomycin pairs, while pair correlations were also noted.No chloramphenicol-resistant strain was isolated. But correlations were found between the MIC values of chloramphenicol and those of the other 4 antibiotics.Forty-seven percent of the 500 strains were resistant to 2 or more antibiotics. One hundred and twenty-six strains (25.2%) were resistant to 2 antibiotics, about half of which were resistant to penicillin and ampicillin. Resistance to 3 antibiotics was shown in 18.6% of strains, the majority being resistant to penicillin, ampicillin, and streptomycin. Eighteen strains (3.6%) were resistant to 4 antibiotics, while no strain was found resistant to all 5 antibiotics.