The Comparison of Antibiotic Susceptibilities of Uropathogenic Escherichia coli Isolates in Transition from CLSI to EUCAST

Abstract

Determination of treatment protocols for infections according to antimicrobial susceptibility test (AST) results is are important for controlling the problem of antibiotic resistance. Two standards are widely used in the world. One of them is Clinical Laboratory Standards Institute (CLSI) standards used in Turkey for many years and the other is the European Committee on Antimicrobial Susceptibility Testing (EUCAST) standards which is used in European Union member countries and came into use in 2015 in Turkey. Since the EUCAST standards had higher clinical sensitivity limits particularly for gram-negative bacilli compared to CLSI (2009) standards, there will be some changes in antibiotic resistance profiles of Turkey with the use of EUCAST. CLSI has changed zone diameters after 2009 versions and the differences between the two standards were brought to a minimum level. Knowledge of local epidemiological data is important to determine empirical therapy which will be used in urinary tract infections (UTI). The aim of this study was to determine the differences of antibiotic susceptibility zone diameters based on our local epidemiological data among uropathogenic Escherichia coli isolates according to EUCAST 2014 and CLSI 2014 standards. A total of 298 E.coli strains isolated from urine samples as the cause of uncomplicated acute UTI agents, were included in the study. Isolates were identified by conventional methods and with BBL Crystal E/NF ID System (Becton Dickinson, USA). AST was performed with Kirby Bauer disk diffusion method and results were evaluated and interpreted according to the CLSI 2014 and EUCAST 2014 standards. According to the results, susceptibility rates of isolates against amikacin (100%) and trimethoprim-sulfamethoxazole (63.09%) were identical in both standards. However, statistically significant differences were observed between CLSI and EUCAST standards in terms of susceptibilities against gentamicin (91.95% and 84.56%, respectively; p= 0.004), cefuroxime axetil (20.13% and 77.18%, respectively; p= 0.000) and levofloxacin (73.83% and 67.11%, respectively; p= 0.044). No statistically differences between two standards for ampicillin (32.89% and 36.24%, respectively; p= 0.219), ampicillin-sulbactam (65.77% and 69.13%, respectively; p= 0.216), ciprofloxacin (72.48% and 71.14%, respectively; p= 0.392) and imipenem (94.63% and 95.30%, respectively; p= 0.426) were determined. In this transitional period, continuity of cooperation between the clinician and microbiology laboratory should be kept forefront and the maintenance of local surveillance studies should be provided by taking into account the changes in antibiotic susceptibility results.

Clinical and laboratory standards institute versus European committee for antimicrobial susceptibility testing guidelines for interpretation of carbapenem antimicrobial susceptibility results for Escherichia coli in urinary tract infection (UTI)

“…A study from Turkey based on Imipenem disc diffusion also showed similar results. [ 5 ] The IS category remained unchanged irrespective of the guideline used (97/501 = 19.36%). The number of absolute resistant strains estimated by CLSI exceeded those by EUCAST.…”

“…Mid-stream urine specimens from suspected UTIs were cultured on HiCrome UTI Agar (HiMedia, Mumbai, India). E. coli strains with significant colony counts (>10[ 5 ] CFU/ml) were included in the study for AST. AST was carried out on Mueller-Hinton agar (Becton Dickinson, Maryland, USA) using a lawn of McFarland 0.5 in normal saline.…”

Five-Year Evaluation of the Urine Culture Results and Antimicrobial Susceptibility Profiles of Isolated E. coli Strains

“…In a study conducted in Ankara in 2015, Süzük et al [35] found the highest resistance, based on CLSI criteria, against cefuroxime axetil (79.8%), ampicillin (67.1%), and ampicillin sulbactam (34.3%) [35]. According to EUCAST criteria, the highest resistance was reported against ampicillin (63.8%), TMP-SMX (27.0%), and ampicillin sulbactam (30.9%).…”

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

“…The results obtained separately by each method showed that amikacin and trimethoprim-sulfamethoxazole susceptibility rates were the same. However, the susceptibility rates were significantly different for gentamicin, cefuroxime axetil, and levofloxacin (19). Kassim et al reported that the AST patterns of E. coli obtained according to the EUCAST 2015 and CLSI 2015 guidelines were similar, excluding AMC, nitrofurantoin, and amikacin.…”