engleski

Characterization and prevalence of extended- spectrum β-lactamases in enterobacteria from Croatian hospital wastewaters

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a major global health problem, and hospital wastewater can be the source and pathway for their transfer to the environment. Here, we describe the occurrence of ESBL-producing enterobacteria and their resistance mechanisms in wastewater from two major hospitals in Zagreb, Croatia. Bio-Rad RAPID'E. coli 2 agar supplemented with cefotaxime (4 mg/L) was used for isolation of presumptive ESBL-producing enterobacteria. Isolate identification was performed using MALDI-TOF MS. Antibiotic susceptibility profiles and ESBL production were phenotypically assessed. The presence of ESBL and carbapenemase genes was detected by PCR and sequencing of selected amplicons. A total of 100 presumptive ESBL- producing enterobacteria were recovered, and among them, the most predominant taxa was Escherichia coli (48%), followed by Citrobacter spp. (14 %), Enterobacter spp. (13 %), Klebsiella spp. (9 %), Acinetobacter spp. (6 %), Enterococcus spp. (6 %), Kluyvera spp. and Raoultella spp. (2 %). Of these isolates, 69 were ESBL-producing enterobacteria, and all were multi-drug resistant, with 52% of them having an extensively-drug resistant phenotype. Most isolates (97 %) were resistant to ceftazidime (3rd generation cephalosporins) and cefepime (4th generation cephalosporins). A subset of 39 ESBL-producing isolates was selected, based on antibiotic susceptibility profiles, for further molecular detection of resistance genes. The predominant ESBL genes among them were blaTEM (95 %, especially blaTEM-116 and blaTEM-1) and blaCTX-M-1 (87 %, with blaCTX-M-1 dominating, and blaCTX-M-3 less prominent), whereas blaSHV (blaSHV-12, blaSHV-28), and blaGES-7 were detected only sporadically. In addition, 57 % of ESBL- producing isolates were resistant to carbapenems, and blaKPC-2 and blaOXA-48 genes were frequently detected. These results demonstrate that hospital wastewater is the source of ESBL-producing and carbapenem-resistant enterobacteria, and support the need for pretreatment of hospital wastewater before it is discharged to the municipal sewer system.

hospital wastewater ; enterobacteria ; extended-spectrum β-lactamases ; carbapenems

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