Journal of Water and Health (Sep 2023)
Antibiotic resistance and virulence potentials of E. faecalis and E. faecium in hospital wastewater: a case study in Ardabil, Iran
Abstract
Hospital wastewater can contaminate the environment with antibiotic-resistant and virulent bacteria. We analyzed wastewater samples from four hospitals in Ardabil province, Iran for Enterococcus faecium and Enterococcus faecalis using culture and molecular methods. We also performed antimicrobial susceptibility testing and polymerase chain reaction testing for resistance and virulence genes. Out of 141 enterococci isolates, 68.8% were E. faecium and 23.4% were E. faecalis. Ciprofloxacin and rifampicin showed the highest level of resistance against E. faecalis and E. faecium isolates at 65%. High-level gentamicin resistance (HLGR), high-level streptomycin resistance (HLSR), ampicillin, and vancomycin resistance were observed in 25, 5, 10, and 5.15% of E. faecium, and 15, 6, 15, and 3.03% of E. faecalis isolates, respectively. The ant(6′)-Ia and ant(3′)-Ia genes that were responsible for streptomycin resistance were observed in HLSR isolates and aph(3′)-IIIa and aac(6′) Ie-aph(2″)-Ia genes accounting for gentamicin resistance were detected in HLGR isolates. vanA was the predominant gene detected in vancomycin-resistant isolates. The majority of isolates were positive for gelE, asa1, esp, cylA, and hyl virulence genes. We found that drug-resistant and virulent E. faecalis and E. faecium isolates were prevalent in hospital wastewater. Proper treatment strategies are required to prevent their dissemination into the environment. HIGHLIGHTS The prevalence of E. faecium isolates in hospital wastewater was three times higher than that of E. faecalis isolates.; Five percent of E. faecium and 3% of E. faecalis isolates were vancomycin-resistant.; The rate of HLSR was almost four times the rate of HLGR among Enterococcus spp.; Almost all of the isolates were multidrug-resistant.; The majority of E. faecalis and E. faecium isolates contained multiple virulence genes simultaneously.;
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