Prevalence of Vancomycin-Resistant Enterococci and Antimicrobial Residues in Wastewater and Surface Water

Abstract

Due to the extensive use of antimicrobial agents in human and veterinary medicine, residues of various antimicrobials get into wastewater and, subsequently, surface water. On the one hand, a combination of processes in wastewater treatment plants aims to eliminate chemical and biological pollutants; on the other hand, this environment may create conditions suitable for the horizontal transfer of resistance genes and potential selection of antibiotic-resistant bacteria. Wastewater and surface water samples (Morava River) were analyzed to determine the concentrations of 10 antibiotics and identify those exceeding so-called predicted no-effect environmental concentrations (PNECs). This study revealed that residues of five of the tested antimicrobials, namely ampicillin, clindamycin, tetracycline, tigecycline and vancomycin, in wastewater samples exceeded the PNEC. Vancomycin concentrations were analyzed with respect to the detected strains of vancomycin-resistant enterococci (VRE), in which the presence of resistance genes, virulence factors and potential relationship were analyzed. VRE were detected in 16 wastewater samples (11%) and two surface water samples (6%). The PNEC of vancomycin was exceed in 16% of the samples. Since the detected VRE did not correlate with the vancomycin concentrations, no direct relationship was confirmed between the residues of this antimicrobials and the presence of the resistant strains.

Prevalence of Antibiotic-Resistant Pathogenic Bacteria and Level of Antibiotic Residues in Hospital Effluents in Selangor, Malaysia: Protocol for a Cross-sectional Study

“…VRE represent an issue of both medical and public health importance, as these bacteria are commonly associated with multidrug-resistant infections and persistent colonization in patients [ 58 ]. From our early findings, the prevalence of vancomycin-resistant E. faecium from two hospitals was more than 80%, which was higher than the prevalence of 11% reported in a study performed in the Czech Republic on isolates collected from Military Hospital Olomouc and University Hospital Olomouc [ 59 ].…”

Enterococci, Van Gene-Carrying Enterococci, and Vancomycin Concentrations in the Influent of a Wastewater Treatment Plant in Southeast Germany

“…Using this approach, a concentration of VREs of 600.4 ± 413.9 cfu/mL and a rate of VREs among total enterococci of 2.0 ± 1.5% (range: 0.3–8.8%) can be calculated. In previous investigations, the proportion of VREs among total enterococci in raw wastewater ranged between 0.5 and 40% [ 16 , 30 , 34 , 35 ]. In catchments having a low prevalence of reported cases, the VRE presence in municipal and even in hospital wastewater remains very low [ 28 , 33 ].…”

“…Isolates from the VRESelect agar were screened using duplex PCR for the presence of van genes, and all strains carried either the vanA (54.6%, n = 94) or the vanB gene (45.4%, n = 78; Figure 1 B). In previous investigations, the relative proportions of vanA - and vanB -carrying E. faecium in wastewater fluctuated widely, up to an exclusive dominance of vanA , depending on local circulation of corresponding strains in the human population [ 16 , 22 , 34 , 41 , 42 ]. However, in all VREs of the present study, van operon types were confirmed, which are the most common in clinical isolates [ 43 ].…”

“…Depending on the origin of the wastewater (municipal or hospital), vancomycin concentrations in raw wastewater range between below the detection limit and more than 10,000 ng/L. In surface waters, up to 2000 ng/L were measured downstream of a discharge [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Residues might induce the acquisition of resistance genes by susceptible strains at an intra- and inter-species level.…”

“…The establishment of predicted no-effect concentrations (PNECs) in environmental waters allows an evaluation of the influence of the measured antibiotics on the development of resistance and selection in the bacterial community of a water resource [ 18 ]. However, studies combining the analysis of concentrations of vancomycin and of the quantitative presence of VREs in municipal wastewaters are rare [ 16 ].…”