Evolution of the antibiotic-resistance of microorganisms causing urinary tract infections: A 4-year epidemiological surveillance study in a hospital population

Background: Urinary tract infections (UTIs) are the leading cause of infection in hospitalised patients. In this study, we describe the most common pathogens involved in the development of UTIs in hospitalised patients, their antibiotic-sensitivity profile and the activity evolution of antibiotics in standard use for treating these infections.

Methods: We retrospectively assessed the results of cultures and antibiograms from urine samples from adult patients hospitalised in the Hospital Complex Virgen de la Nieves (Granada, Spain) with a microbiological confirmation of UTI between January 2013 and December 2016.

Results: We identified 4,347 microorganisms (3,969 bacteria and 378 yeasts). During the 4years of the study, Escherichia coli was the most common species isolated in both sexes; however, 62.9% of the UTIs were caused by other microorganisms. The presence of multiresistant microorganisms such as Acinetobacterspp. (1.2%) and extended-spectrum beta-lactamase-producing enterobacteria (10.0%) and carbapenemase-producing enterobacteria (0.3%) were also relevant findings. Imipenem, piperacillin-tazobactam and fosfomycin presented activity rates above 80%, considering all causal microorganisms of UTI, while the other tested antibiotics presented activity rates below 70%.

Conclusion: Imipenem and piperacillin-tazobactam were the most active antibiotics in hospital use, which makes them first-line antibiotics in the empiric treatment of UTIs in this healthcare setting. The use of other antibiotics should be limited to conditions of demonstrated or highly probable sensitivity.