Comparison of E test with agar dilution for antimicrobial susceptibility testing of Neisseria gonorrhoeae

Abstract

A collection of 150 Neisseria gonorrhoeae isolates from Africa, where various resistance mechanisms among N. gonorrhoeae isolates are common, was used to the compare E test (AB Biodisk, Solna, Sweden) with agar dilution susceptibility testing. MICs obtained by the E test agreed within 1 log2 concentration by the agar dilution method for 97.5, 97.3, 96.6, 94, and 84.7% of the tested isolates for penicillin, ciprofloxacin, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole, respectively. No significant difference in susceptibility categorization was observed between either method. The E test is an attractive alternative to the agar dilution technique and is a more appropriate method for N. gonorrhoeae susceptibility testing in developing countries.