5 research outputs found
In vitro Comparison of Disk Diffusion and Agar Dilution Antibiotic Susceptibility Test Methods for Neisseria gonorrhoeae
At present, most Neisseria gonorrhoeae testing is done with
beta-lactamase and agar dilution tests with common therapeutic agents.
Generally, in bacteriological diagnosis laboratories in Argentina,
study of antibiotic susceptibility of N.gonorrhoeae is based on
beta-lactamase determination and agar dilution method with common
therapeutic agents. The National Committee for Clinical Laboratory
Standards (NCCLS) has recently described a disk diffusion test that
produces results comparable to the reference agar dilution method for
antibiotic susceptibility of N.gonorrhoeae, using a dispersion diagram
for analyzing the correlation between both techniques. We obtained 57
gonococcal isolates from patients attending a clinic for sexually
transmitted diseases in Tucuman, Argentina. Antibiotic susceptibility
tests using agar dilution and disk diffusion techniques were compared.
The established NCCLS interpretive criteria for both susceptibility
methods appeared to be applicable to domestic gonococcal strains. The
correlation between the MIC's and the zones of inhibition was studied
for penicillin, ampicillin, cefoxitin, spectinomycin, cefotaxime,
cephaloridine, cephalexin, tetracycline, norfloxacin and kanamycin.
Dispersion diagrams showed a high correlation between both methods. {P
Agar dilution method for susceptibility testing of Neisseria gonorrhoeae
The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending a clinic for sexually transmitted diseases in Tucumán, Argentina, were determined by the agar dilution method (MIC). 3.5% of the isolates produced ²-lactamase. A total of 96.5% of ²-lactamase negative isolates tested were susceptible to penicillin (MIC < 2 µgml-1); 14.03% of the tested isolates were resistant to tetracycline (MIC < 2 µgml-1), and 98% of the tested isolates were susceptible to spectinomycin (MIC < 64 µgml-1). The MICs for 95% of the isolates, tested for other drugs were: < 2 µgml-1 for cefoxitin, < 0.06 µgml-1 for cefotaxime, < 0.25 µgml-1 for norfloxacin, < 10 µgml-1 for cephaloridine, < 10 µgml-1 for cephalexin, and < 50 µgml-1 for kanamycin. Antibiotic resistance among N. gonorrhoeae isolates from Tucumán, Argentina, appeared to be primarily limited to penicillin and tetracycline, which has been a general use against gonorrhoeae in Tucumán since 1960. Periodic monitoring of the underlying susceptibility profiles of the N. gonorrhoeae strains prevalent in areas of frequent transmission may provide clues regarding treatment options and emerging of drug resistance