A decreasing susceptibility of gonococcal strains to antimicrobials has been observed in most parts of the world, and less susceptible strains have been noted especially in South-East Asia, Africa, and Far East including Korea. It has led to reevaluate the treatment of gonorrhea and search for effective treatment regimens in these countries. A periodic determination of MIC to antibiotics is paramount importance in this regard.
Male patients with uncomplicated gonococcal urethritis attending the Venereal Disease Clinic of Choong-ku Public Health Center in Seoul from Sep 1982 to Mar 1984 were studied.
One hundred eighty-two gonococcal strains were isolated from these patients and in-vitro studies for susceptibility to antibiotics were made. One hundred strains were found to produce beta-lactamase by chromogenic cephalosporin method.
The minimum inhibitory concentrations (MICs) were tested by the plate dilution method on penicillin, ampicillin, teracycline, thiamphenicol, and cefoperzone.
Fifty-five patients were treated with penicillin (Pc 6 MIU i.m. plus probenecid I.Ogm p.o.), 87 patients with thiamphenicol (2.5gm p.o.). and 50 patients with kanamycin (2.Ogm i.m.). The treatment results were compared with MICs of antibiotics used for the treatment.
The results are summarized as follows:
1). There is a markedly lower susceptibility of gonococcal strains to penicillin, ampicillin, tetracycline, and thiamphenicol, respecively. In contrast, there is a relative susceptibility to cefoperazone.
For the beta-lactamase negative strains, the frequency of strains with relative resistance (RR) to penicillin (MIC>0.5mcg/ml), ampicillin (MIC>0.5mcg/ml), tetracycline (MIC?2.0mcg/ml), and thiamphenicol(MIC>2.0mcg/ml) was found to be 7201o, 60.507o 67.1%, and 35.907o, respectively.
For the beta-lactamase positive strains, the frequency of strains with relative resistance to tetracyline and thiamphenicol was found to be 83% and 81.801o, respectively. Beta-lactamase positive strains were significantly less susceptible to tetracycline (t = 8.3, p<0.005), thiamphenicol (t = 3. 1, p<0.001) and spectinomycin (t = 9.9, p<0.005) than beta-actamase negative strains.
2) The ED,o of beta-lactamase negative strains to penicillin, tetracycline and spectinomycin in-creased from 0.36mcg / ml, 1.08mcg / ml and 5.93mcg / ml in 1982 to 1.63mcg / ml, 2.6mcg / ml and 8.95mcg/ml in 1984, respectively. While ED50 of beta-lactamase positive strains to tetracycline increased from 3.2mcg/ml in 1982 to 4.7mcg/ml in 1984, that to spectinomycin decreased from 11.2mcg/ml in 1982 to 9.27mcg/ml in 1984.
3) Treatment failure rate in infections with beta-lactamase negative strains was found to be correlated with MICs of antibiotics used for the treatment, namely; penicillin (r = 0.903, p<0.05, Y = 0.019 + 0.05x), thiamphenicol (r 0.956, p<0.05, Y = 0.142 + 0.114x) and kanamycin, (r = 0.967, p <0.05, Y = 0.07 + 0.033x).
For beta-lactamase positive strains, the MICs of the thiamphenicol(xI = 3.8, p<0.1) or kanamycin (p<0.05) was higher in the treatment failure group than in the treatment success group.
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