The objective of this study was to evaluate the frequency of different extended-spectrum β-lactamases (ESBL) as well as to associate these ESBL with antimicrobial (ATM) resistance in Escherichia coli and Klebsiella spp. isolates from outpatients and inpatients with urinary tract infections. The study included 435 consecutive nonduplicate clinical isolates, including 362 E. coli isolates, 62 Klebsiella pneumoniae isolates, and 11 K. oxytoca isolates. Isolates were obtained from patients who were treated in a University Hospital between August 2012 and July 2013. Three multiplex PCR were performed to identify the ESBL groups. A total of 48 (11%) ESBL-producing isolates were found. The risk for the ESBL presence was significantly higher in males (26.4%) than females (8%), from hospital-acquired infections (29.1%) than community-acquired infections (7.0%) and in Klebsiella spp. (27.4%) than in E. coli (7.7%). ESBL-producing isolates presented a significantly higher percentage of resistance in 21 of the 23 ATMs analyzed. The CTX-M-1 group was the most predominant ESBL identified. The blaCTX-M-1-group gene was found in 56% of the total ESBL producers from community and in 42.4% from hospital origins; it was followed in frequency by the blaCTX-M-8/25-group, also found in both environments. Klebsiella spp. presented the largest variety of β-lactamase enzyme combinations and a higher level of resistance to cefotaxime. These findings contribute to better knowledge of the epidemiology of ESBL enzymes and are alarming for the reduced therapeutic options available for the risk groups identified in the studied populations.
Keywords: ESBL; antimicrobial resistance; multidrug resistance.