Bacteriological aspects and risk factors for the acquisition of ESBL producing Enterobacteriaceae in urinary tract infections in the elderly

Abstract

Aim. Our study aimed to know the antibiotic resistance of the isolated strains, as well as the risk factors for acquiring extended-spectrum betalactamase-producing Enterobacteriaceae, in the urinary tract infection of the elderly. Methods. All the urine specimens received from elderly people at the Microbiology Laboratory of Batna Hospital, Algeria, from March 2012 to March 2014 were included in a prospective observational study. The bacteria were identified by API gallery or mass spectrometry. The antimicrobial susceptibility testing was performed as per CLSI guidelines. Multi-drug resistant gramnegative bacilli were studied by PCR and sequencing to determine their resistance mechanisms. The risk factors for ESBL-E acquisition were determined by univariate analysis. Results. From a total of 1024 urinary specimens, 372 microorganisms were isolated. The resistance rates of the community Escherichia coli strains to amoxicillin-clavulanic acid (51.2%) and ciprofloxacin (26.5%) were high. In Enterobacteriaceae, ESBL (11.4%) were all of the CTX-M type, mainly the CTX-M-15 variant, often associated with the qnrB gene. The CTX-M-1 type predominated in E. coli. The carbapenemases produced by non-fermenting bacilli were of the oxacillinase-23 and VIM types while none were produced by Enterobacteriaceae. A recent history of surgery and antibiotic treatment were the main risk factors identified in the ESBL-E acquisition. Conclusion. This study is the first to describe the antibiotic resistance of UTI strains in the elderly in Algeria. Risk factors identified in the acquisition of resistant uropathogens highlight the importance of good hygiene practices and antimicrobial prescription.