Prevalence and antimicrobial resistance of beta-lactamase-producing Gram-negative isolates from outpatient clinical and environmental samples in the Zenica-Doboj Canton, Bosnia and Herzegovina

Infections due to extended-spectrum beta-lactamase (ESBL)-producing isolates in patients are hard to treat and cause high morbidity and mortality. ESBL-producing bacteria have been increasingly detected in environmental samples in different countries since 2002, and have gained considerable attention worldwide.Methods: Antibiotic susceptibility of all isolates was determined using the disk diffusion method. The production of ESBLs was determined by the double-disk synergy test.Results: Among the outpatient clinical samples, out of 2857 Gram-negative bacteria, 184 (6.5%) ESBL-producing bacteria were isolated. In this group, 143 (77.7%) were from urine samples, 26 (14.1%) from surgical wounds, 6 (3.3%) from umbilical swabs, and 9 (4.9%) from other patients sites (upper respiratory tract, cannula, eyes, genital swabs). Escherichia coli was isolated in 62 (33.7%), and Klebsiella spp. in 50 (27.8%) cases. Among the environmental samples, out of 381 Gram-negative bacteria, 52 (13.6%) were ESBL-producing isolates. In this group, 37 (71.2%) were sampled from water, 7 (13.5%) from food, and 8 (15.4%) from environmental surfaces. The most prevalent ESBL-producing bacteria isolated from the environmental samples were E. coli (isolated from 26 samples), Klebsiella spp. (10), non-fermenters (9), and other bacteria isolated from 7 samples. The clinical outpatient ESBL-producing isolates showed resistance to all cephalosporins, ranging from 25% (cefepime) to 100% (cefuroxime). The environmental ESBL-producing isolates showed resistance to cefuroxime, aztreonam, cefpodoxime, amoxicillin/clavulanate, and cefoxitin in the range of 65-100%.Conclusions: Prevalence of antibiotic resistance of ESBL-producing strains is high and requires routine detection of ESBL-producing isolates in the laboratories, designing of appropriate antibiotic prescribing policies and control of the risk factors.