Changes in Enterococcal Populations and Related Antibiotic Resistance along a Medical Center-Wastewater Treatment Plant-River Continuum

Abstract

e To determine if hospital effluent input has an ecological impact on downstream aquatic environment, antibiotic resistance in Enterococcus spp. along a medical center-retirement home-wastewater treatment plant-river continuum in France was determined using a culture-based method. Data on antibiotic consumption among hospitalized and general populations and levels of water contamination by antibiotics were collected. All isolated enterococci were genotypically identified to the species level, tested for in vitro antibiotic susceptibility, and typed by multilocus sequence typing. The erm(B) and mef(A) (macrolide resistance) and tet(M) (tetracycline resistance) genes were detected by PCR. Along the continuum, from 89 to 98% of enterococci, according to the sampled site, were identified as Enterococcus faecium. All E. faecium isolates from hospital and retirement home effluents were multiply resistant to antibiotics, contained erm(B) and mef(A) genes, and belonged to hospital-adapted clonal complex 17 (CC17). Even though this species remained dominant in the downstream continuum, the relative proportion of CC17 isolates progressively decreased in favor of other subpopulations of E. faecium that were more diverse, less resistant to antibiotics, and devoid of the classical macrolide resistance genes and that belonged to various sequence types. Antibiotic concentrations in waters were far below the MICs for susceptible isolates. CC17 E. faecium was probably selected in the gastrointestinal tract of patients under the pressure of administered antibiotics and then excreted together with the resistance genes in waters to progressively decrease along the continuum.

Drug-resistant and hospital-associated Enterococcus faecium from wastewater, riverine estuary and anthropogenically impacted marine catchment basin

“…In our estimation, hospital wastewater constitutes approximately 0.2% of both WWTPs’ daily inflow. The release of hospital-associated clones of E. faecium to the environment was observed also by others [24,28,35,36]. In our study, isolates belonging to the major nosocomial HiRECC (formerly named CC17) constituted altogether 24.6% of all isolates of E. faecium subjected to typing, and were present at all sampling sites.…”

Virulence and antimicrobial resistance of Enterococcus faecium isolated from water samples

“…; Leclercq et al . ), we found that Ent. faecium were the most common isolates among the enterococcal populations with 28·9% ( n = 153) of the cases.…”

“…; Leclercq et al . ). The source of water microbial contamination such as enterococci has been through livestock and poultry, municipal and hospital sewages and wildlife faecal contamination (Byappanahalli et al .…”

Enterococci and Their Interactions with the Intestinal Microbiome

“…E. faecalis can survive in nutrient-poor environments, such as sterilized waste for up to 12 days (134). Enterococci are frequently found in human sewage, particularly outside hospitals (135). Not surprisingly, enterococcal strains isolated from effluents are antibiotic resistant.…”