Study aims to investigate antimicrobial resistance of uropathogenic E. coli from elderly patients

Urinary Tract Infection (UTI) is a common cause of morbidity and mortality in older adults. Escherichia coli is one of the bacterial agents with higher prevalence in community-acquired and health care associated urinary infections in elderly patients. Worldwide, a rise of Extended Spectrum Beta-Lactamase (ESBL) producing E. coli and multi-resistant isolates has been reported. The aim of this study was to investigate antimicrobial resistance of uropathogenic E. coli from elderly patients in a General Hospital, Argentina. During the period July 2011-July 2015, an observational, prospective study was carried out. Patients over 70 years old with urinary tract infections, without urinary catheters and with no antimicrobial therapy the previous week before sampling, were included.

768 bacterial isolates were identified as E. coli. Resistances to ampicillin (80.5%), nalidixic acid (61.7%), ciprofloxacin (42.8%), TMS (37.6%), amoxicillin-clavulanate (28.6%), cefazolin (21.6%), cefuroxime (20.7%), gentamicin (13.8%), cefotaxime (9.7%), ceftazidime (9.7%), cefepime (8.4%), cefoxitin (3.1%) and nitrofurantoin (2.3%) were observed. Resistance to carbapenems was not expressed. Production of extended spectrum β-lactamases was detected (7.6%) in community acquired (96%) and healthcare associated (4%) isolates. The independent risk factors for urinary infections produced by multi-resistant E. coli were: diabetes mellitus, recurrent infections, hospitalization during the last year and exposure to β-lactams in the last 3 months.

In this study, a high prevalence of resistance to β-lactams as well as to other antimicrobials were observed in E. coli isolates from elderly patients with UTI. Based on the results of this research we suggest to avoid using quinolones or TMS for patients older than 70 years old with at least one of the previously mentioned independent risk factors. Detection of these strains represents an alarm signal that motivates a continuous surveillance of antimicrobial resistance in adult patients with urinary infections produced by E. coli.