Antimicrobial Resistance and Extended Spectrum Beta-Lactamase Agents in Urinary Tract Infections: a Serious Problem in the North of Mexico

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Inappropiate use of antibiotics has developed an increase incidence of resistant strains in urinary tract infections (UTI) in the past decades. The incidence of Extended Spectrum Beta-Lactamase (ESBL) agents has increase in community aquired-UTI, reaching up to 11% in some studies. The aim of this study is to describe causal agents, prevalence of drug resistance and to determine the risk factors for ESBL-producing agents in UTI.


The study was done in a tertiary-care teaching hospital in Monterrey, Mexico. All positive urine cultures from outpatients and hospitalized patients with UTI from March to October 2015 were included. Drug resistance profile was determined using microdilution plate. The antibiotics tested included amikacin, gentamicin, amoxicillin-clavulanate, aztreonam, ceftriaxone, ertapenem, ciprofloxacin, levofloxacin, nitrofurantoin, fosfomycin, trimethoprim-sulfamethoxazole, and colistin. Statistical analysis was performed with the SPSS software version 20.0. Clinical and demographic characteristics were analyzed using ?2 test for categorical variables, and T-test for continuous variables. Statistical significance was set at p


A total of 353 positive urine cultures were confirmed. Hospitalized UTI were 34.5% (n=122) and 65.5% (n=231) were community acquired UTI. The production of ESBL was found in 21.5% of strains. High resistance to amoxicillin-clavulanate (over 75%) and moderate resistance rates to gentamicin, aztreonam, ceftriaxone, ciprofloxacin, levofloxacin, fosfomycin, and trimethoprim-sulfamethoxazole were detected. ESBL-producing agents were associated with complicated UTI (p=


One every five UTI are caused by ESBL agents. The emergence of ESBL-producing strains is a serious health problem both in our community and hospital setting. An alarmingly high resistance to antibiotics recommended as first-line empirical therapy in UTIs (fosfomycin, fluoroquinolones and trimethoprim-sulfamethoxazole) was observed in both outpatient and inpatient strains.

Funding: none