Detection of minimum inhibitory concentration of cefuroxime and ceffriaxone for neisseria gonorrhoeae

Abstract

To determine the presence and the extent of cefuroxime resistance among / Neisseria gonorrhoeae isolates a~ the central STD laboratory in Colombo during the period August 2004 - October2004. The agarl dilution method was used to determine the minimum inhibitory concentrations (l\1ICs) to cefuroxime and ceftriaxone. The sensitivities of all strains to the two antibiotics were interpreted jCCOrding to NCCLS criteria. Isolates from first visits and positive test of bure (TOC) cultures were analysed separately. Out of the J 141 isolates, MIC testing for both antibiotics was successfu1 in 108 (77 present ) isolates. outl of 58 (41 present 1 patients who returned for test of cure, II (19 present ) were / confirmed positive. At MIC testing for cefmoxime, M1C range was 0.031 mcg/ml to·] mcg/ml. l\1IC50 was 0.25 mcg/ml and l\1IC90 was 0.5 mcg/ml. For ceftriaxone, l'v1J.C range was from 0.001 mcg/ml to 0.063 mcg/ml. MIC50 and MIC90 were 0.008 mcg/ml and 0.016 mCg/mlrrspectively. In the positive TOC cultures most isolates showed MICs of 0.5 - 1 mcg/ml for cefuroxime, with a different pattern of distribution to that of 108 isolates from first visits. ceftrialone MICs for TOC positive isolates gave similar distribution pattern ~o that of 108 isolates from first visits. All is1lates tested ,ere sensitive to cefuroxime. Therefore, cefuroxime can be continued as drug of choice f0r gonorrhoea in Sri Lanka .. However continued regular l\1IC surveillance studies are important. MICs of all isolates for ceftriaxone was very much lower than the cut off level. Therefore ceftriaxone could continue to be used as the alternative or as the first line antibiotic.