Comparative Antimicrobial Susceptibility Profiles of Uropathogenic Extended-Spectrum ß-Lactamase Producing Strains of Klebsiella pneumonia and Escherichia coli by the CLSI and EUCAST Methodologies

Abstract

Objective: This study aimed to compare the CLSI and EUCAST interpretations of the antimicrobial susceptibility test results of the ESBL–producing uropathogenic Escherichia coli and Klebsiella pneumonia strains.

Methods: After obtaining ESBL-producing E. coli and K. pneumonia isolates from the urine specimens of the patients, Kirby-Bauer’s disc diffusion method was used for conducting antimicrobial susceptibility test. The test procedures and the interpretation of the results were carried out according to both of the two guidelines. For the statistical comparison of concordance between the two guidelines, the Kappa coefficients and the concordance rates were calculated.

Results: The results were graded in the range from perfect to poor agreement. For E. coli,  interpretations of the AST results revealed a moderate to perfect agreement between both methods. Weighted Kappa agreement scores in the range from 0.42 to 1. The agreement for AMC, TPZ30/6, ceftazidime 10, meropenem, and aztreonam was poor without any inconsistencies. For Klebsiella, the kappa agreement score was in the range from 0.25 to 1. It was incompatible with AMC, TPZ 30/6, ceftazidime 10, aztreonam; there was poor agreement for cefepime, amikacin and ertapenem.

Conclusions: Our results showed agreement between the two guidelines for Escherichia coli and Klebsiella pneumoniae but also showed inconsistencies between two guidelines. Therefore, it contribute to the comparison of these guidelines for interpreting antibiotic susceptibilities.