METHODS: During a period of 1 year, midstream urine specimens received in the laboratory were cultured by conventional techniques and 2932 of them grew significant colony counts of Escherichia coli. Out of them, 501 E. coli isolates which were resistant to at least six first-line antibiotics were further subjected to second-line antimicrobials imipenem and meropenem, reported by E-tests (bioMerieux, France). The E-test results were interpreted by both CLSI 2016 and EUCAST 6.0 (2016) guidelines. Weighted kappa was used to determine absolute agreement, and McNemar\'s Chi-square test was used to test the difference in proportions of susceptibility between two methods, respectively.
RESULTS: Taking CLSI guidelines as a gold standard, there was 100% sensitivity in a susceptible category by the EUCAST guidelines for both the carbapenems. Weighted kappa showed good and moderate agreement between them for imipenem and meropenem, respectively. However, McNemar Chi-square test in the nonsusceptible category between the two tests was 9.38% and 33.03% for imipenem and meropenem, respectively, and they were highly significant (P < 0.001).
CONCLUSIONS: A laboratory can follow EUCAST guidelines as well and the guidelines are more useful in urinary concentrated antibiotics such as carbapenems. Further other antibiotics need to be evaluated by both these guidelines.