Introduction To evaluate the clinical value of E-test method to determine the antimicrobial susceptibility of Neisseria gonorrhoeae (N.gonorrhoeae) to five antibiotics.

Methods A total of 100 n.gonorrhoeae strains were collected. The agar-dilution method, E-test and K-B method were used to determine the minimum inhibitory concentration(MIC) of five antibiotics including ciprofloxacin, ceftriaxone, spectinomycin, penicillin and azithromycin. Assessment of agreement were made between the E-test and the reference agar dilution test. The comparisons include of discrepancy rate and correlation coefficients were made between the E-test and K-B method.

Results The MIC50,MIC90 and rang of MIC values were either identical or only differed by 0.5 to 1.5 dilution step. All antimicrobial agents had excellent essential agreement(72% to 98%)%).Ciprofloxacin had the highest essential agreement(98%),followed by azithromycin(92%),while penicillin had the lowest essential agreement(72%). In addition to the discrepancy rate with E-test for penicillin was higher than the K-B method, the other four antibiotics were just the opposite. The correlation coefficients between the E-test and the reference agar dilution test for other four antibiotics were significantly higher than the K-B method.

Conclusion The E-test method for ciprofloxacin and azithromycin can be used as an alternative method of agar dilution method used in clinical, but the E-test method for ceftriaxone and spectinomycin may lead the results to low. And the E-test method for penicillin is not suitable to used in clinical because of the low essential agreement and high minor discrepancy.