Molecular characterization and antimicrobial susceptibility pattern of extended-spectrum beta-lactamase-producing Escherichia coli as cause of community acquired urinary tract infection

Background: Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum beta-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the bla(CTX-M-15) gene, is a growing phenomenon worldwide. Aim: To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods: A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results: 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the bla(CTX-M) gene. Conclusions: One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.