Prevalence and molecular characterization of Extended Spectrum Beta-Lactamases (ESBLs) producing Escherichia Coli and Klebsiella Pneumoniae.

The aim of this study was to determine the prevalence of ESBL-producing Escherichia coli and Klebsiella pneumoniae as well as genes encoding ESBLs.

Methods: A total of 1207 non-repeat isolates of E. coli and K. pneumoniae were obtained from urine, tracheal aspirate, wound swab and blood from patients hospitalized at the University Clinics in Skopje. ESBL set and E-test were used for phenotypic detection of ESBL-production. Multiplex PCR was used to identify genes for different types of ESBLs in 100 ESBL positive strains (E. coli-52 and K. Pneumoniae-48), randomly selected.

Results: Out of 804 E. coli isolates and 403 K. pneumoniae isolates, 126 (15.7%) and 125 (31%) isolates were ESBL producers, respectively. The prevalence of ESBL-positive strains of E. coli in surgery clinics (42 out of total of 211-19.9%) and K. Pneumoniae (61 out of a total of 161-37.9%) was higher compared to those in the clinics of internal medicine (84 out of 593-14.2%) and (64 out of 242-26.4%), respectively. Only 87 of ESBL positive isolates could be typed for one or more genes. Among the isolates of E. coli and K. pneumoniae harbouring a single ESBL gene (39%), blaSHV, blaTEM and blaCTX-M were present in 19.5%, 16% and 3.4% strains, respectively. Two or more genes for ESBL were present in 61% of ESBL isolates; blaTEM+blaSHV being the most common combination.

Conclusions: The majority of strains harboured two or more ESBL genes and the most common phenotypes were TEM, SHV and CTX-M. Identification of the genes is necessary for the surveillance of their transmission in hospitals.