Abstract
Hospital effluents are a source of environmental pollution by drugs, antibiotic-resistant bacteria, and resistance genes. Quinolones, particularly ciprofloxacin, are commonly detected in these effluents, contributing to the emergence of antimicrobial resistance. The objective of this study was to characterize ciprofloxacin-resistant Enterobacteriaceae in hospital effluents. Isolates were selected on Tergitol-7 agar supplemented with ciprofloxacin and genotyped by ERIC-PCR. Antibiotic susceptibility testing was done using the disk diffusion method, and minimum inhibitory concentrations were determined using the agar dilution method. Resistance genes, integrons, phylogenetic groups, and sequence types were identified by PCR and sequencing. A total of 17 ciprofloxacin-resistant isolates were characterized: Escherichia coli, Escherichia vulneris, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter freundii, and Citrobacter koseri/farmeri. Isolates presented concomitant resistance to nalidixic acid, ciprofloxacin, ofloxacin, and pefloxacin. A diversity in mutation patterns in gyrA and parC genes and new amino-acid substitutions in GyrA subunit were observed. Quinolone plasmidic resistance genes qnrB1, qnrB2, qnrB5/19, qnrS1, and aac(6')-Ib-cr were detected. Resistance to other antibiotic classes was observed. Class 1 integrons and resistance genes blaCTX-M-15, blaOXA-1, sul1, sul2, sul3, tetA, tetB, aadA1/2, aadA5, aph(3')-Ia, aac(3)II, dfrA1, dfrA5, dfrA7, and dfrA12 were detected. Bacterial tolerance to cadmium, zinc, and mercury was observed with the presence of the merA gene. E. coli isolates belonged to phylogenetic groups A, B1, and D and to sequence types ST405, ST443, ST101, ST10, and ST347. This study highlighted bacterial multidrug resistance linked to ciprofloxacin and, consequently, the risk of bacterial exposure to this antibiotic.
Highlights
Hospital effluents are a source of environmental pollution by drugs, antibiotic-resistant bacteria, and resistance genes
We proposed, in this study, to characterize the ciprofloxacin resistance in Enterobacteriaceae isolates collected from the wastewater of a hospital in Algiers
Enterobacteriaceae isolates was recovered and identified; they were divided into 51 isolates of Escherichia coli, 4 Klebsiella pneumoniae, 2 Citrobacter freundii, 1 Klebsiella oxytoca, 1 Escherichia vulneris, and 1 Citrobacter koseri/farmeri
Summary
Hospital effluents are a source of environmental pollution by drugs, antibiotic-resistant bacteria, and resistance genes. Quinolones, ciprofloxacin, are commonly detected in these effluents, contributing to the emergence of antimicrobial resistance. The objective of this study was to characterize ciprofloxacin-resistant Enterobacteriaceae in hospital effluents. Quinolone plasmidic resistance genes qnrB1, qnrB2, qnrB5/19, qnrS1, and aac(6’)-Ib-cr were detected. A worldwide constant increase in bacterial resistance to quinolones was observed during the last decade, inherent to the massive use of antibiotics in human therapy and in intensive livestock, poultry, in some countries [1,2]. Hospital effluents discharged into the sewer system, usually without pre-treatment, have been reported to be an influent source of antimicrobial residues and antibiotic-resistant bacteria to the wastewater treatment plant (WWTP) [3]. Quinolones are excreted in their biologically active form and released in aquatic environments, especially hospital effluents, where they are stable and may impact bacterial antibiotic resistance [3,4]. Quinolones, ciprofloxacin, are distinguished by the cross-resistance between them and with non-quinolone antimicrobials [6,7], the interest of the characterization of quinolone resistance selected by the complex environment of hospital effluents, more so as Anssour et al –Antimicrobial resistance in hospital effluents
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