Objective:

To describe the causal agents, prevalence of antimicrobial resistance, and risk factors associated with extended spectrum beta-lactamase (ESBL)-producing agents in urinary tract infections (UTIs).

Materials and methods:

A retrospective study was conducted at a tertiary care hospital in Monterrey, Mexico. Inclusion criteria were patients that clinically presented with a UTI and had a positive urine culture, within the time frame of March to October 2017. The association with ESBL-producing agents was determined through the Χ2 test for categorical variables. Statistical significance was set at a p <0.05, utilizing SPSS version 20.0 software.

Results:

A total of 353 positive urine cultures were confirmed. ESBL production was found in 21.5% of the strains. There was a high level of resistance (>50%) to amoxicillin-clavulanate, ciprofloxacin, levofloxacin, fosfomycin, and trimethoprim-sulfamethoxazole and moderate resistance (10-50%) to gentamicin and ceftriaxone. Amikacin, ertapenem, nitrofurantoin, and colistin had the lowest resistance rates (<10%). The ESBL-producing agents were associated with complicated UTI (p≤0.0001). The comorbidities associated with ESBL-positive UTIs were diabetes mellitus (p=0.02) and immunodeficiency (p=0.008), as was having undergone radiotherapy (p=0.025) and previous antibiotic use (p≤0.001).

Limitations:

The clonal relationship of isolates, especially of E. coli, was not analyzed. We could not establish whether there was a high level of genetic diversity between the isolates or whether independent acquisition or cross-transmission occurred.

Value:

We evaluated the epidemiologic characteristics of the ESBL-producing agents in UTIs at a Mexican tertiary care hospital.

Conclusions:

One out of every five UTIs was caused by ESBLs in our study population. There was a high level of resistance to the antibiotics used as first-line empiric therapy in the patients studied.

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