Background:

The aim of the present study was to evaluate the isolation of extended spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) strains in patients with urinary tract infections.

Materials and methods:

A retrospective study was conducted on patients seen at the Departamento de Salud de Castellón, Spain, within the time frame of January 2012 to December 2016, whose urine cultures were positive for E. coli. The following variables were analyzed: age, sex, type of patient (outpatient or hospitalized), and risk factors. The prevalence of ESBL-producing E. coli was determined through a descriptive analysis.

The statistical analysis was carried out utilizing the SPSS 18.0 program. The quantitative variables were analyzed using the Student’s t test and the qualitative variables with the chi-square test.

Results:

A total of 11,740 cultures were obtained that were positive for E. coli and 446 (3.79%) of them had the ESBL-producing E. coli strains. The percentage per year of ESBL-producing E. coli infection ranged from 1.7% to 6.5%, showing an increasing trend in the isolation of the resistant strains in more recent years. Mean patient age was 68.9 years, and there were no differences between the sexes. A total of 350 cultures corresponded to outpatients (78.7%), 70.5% of whom were women. The risk factors most associated with ESBL were: having presented with a urinary tract infection (UTI) within the past year and having received antibiotic treatment within the previous 3 months. Fifty percent of the patients that had received an antibiotic had been given a beta-lactam.

Conclusions:

The isolation of ESBL-producing E. coli strains was similar to that found in other case series. There was an increase in the prevalence of those difficult-to-treat infections. The majority of the patients were outpatients, had previously been treated with antibiotics, and presented with recurrent UTIs.

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