Antibiotic and Disinfectant Susceptibility Profiles of Vancomycin-Resistant Enterococcus faecium (VRE) Isolated from Community Wastewater in Texas

Abstract

Vancomycin-resistant Enterococcus faecium (VRE) from human wastewater effluents in a nonclinical semiclosed agri-food system in Texas were characterized for susceptibility to antibiotics and disinfectants. The 50 VRE were resistant to eight fluoroquinolones and 10 of 17 antimicrobials typically active against Gram-positive organisms. The VRE were susceptible to quinupristin/dalfopristin and linezolid. Lack of the insertion element IS1251 correlated with VRE susceptibility to streptomycin and gentamicin at p < 0.0001 and p = 0.033, respectively. An association was observed between pulsed-field gel electrophoresis genotypes Ic and II and susceptibility to streptomycin at p = 0.0006. VRE susceptibility for nine disinfectants and five disinfectant components is shown. Ninety-two percent of the isolates had a minimum inhibitory concentration (MIC) for triclosan > or =2 ppm. Triclosan MICs for many of the VRE were well over expected product application levels. No association was observed between antibiotic resistance and disinfectant susceptibility in these VRE. Enterococci multiply-resistant to vancomycin and aminoglycosides were found in a non-hospital environment where one would not expect to find them.

Chlorhexidine Induces VanA-Type Vancomycin Resistance Genes in Enterococci

“…H-CHG MICs for all enterococci queried (Table 1) ranged from 2.5 to 9.8 g/ml. These values are in the range expected based on previous literature (25)(26)(27)(28)(29). For further confirmation, the MIC of a chlorhexidine digluconate solution from Sigma-Aldrich was determined for E. faecium 1,231,410 and found to be identical to the H-CHG MIC.…”

“…Previous studies have reported that E. faecium and E. faecalis chlorhexidine MICs range from 0.5 to 16 g/ml and that chlorhexidine MICs for VRE and vancomycin-sensitive enterococci are similar (25)(26)(27)(28)(29). The over-the-counter chlorhexidine gluconate product Hibiclens (referred to as H-CHG here) was selected for our studies because we sought to evaluate a widely available chlorhexidine-containing consumer product.…”

“…A recent study semiquantitatively evaluated chlo-rhexidine levels on the skin of 20 patients pre-and post-chlorhexidine bathing, finding that the levels varied depending on body site and time postbath (24). Levels within the reported range of chlorhexidine MIC for enterococci (25)(26)(27)(28)(29) were detected on patient skin (24). In another study, chlorhexidine susceptibilities were monitored for CLABSI enterococcal isolates obtained from hospital wards using chlorhexidine bathing (30).…”

Role of House Flies in the Ecology of Enterococcus faecalis from Wastewater Treatment Facilities

“…Waste received from environments under significant antibiotic pressure, such as hospitals, consistently contains a greater proportion of singly and multiple drug-resistant bacteria [9,22,26,28,38,60] and AR enterococci are commonly recovered from sewage [2,8,9,28,38,47,51,55]. House flies and other filth flies often have direct and unhindered access to many steps in the waste processing flow and therefore may acquire bacteria associated with the waste.…”

Disinfectant and Antimicrobial Susceptibility Profiles of Salmonella Strains from Feedlot Water-Sprinkled Cattle: Hides and Feces

“…Bacteria in the food chain continuum are controlled by strategies that include the use of biocides as antiseptics and disinfectants (see our paper on interactions of organic acids with Salmonella [25]). Disinfectants are chemicals that inhibit or kill a broad-spectrum of microorganisms [26], often contain a variety of active ingredients, and are routinely used in animal production, veterinary medicine, the food processing industry, human medicine, restaurants, and consumers' homes [27]. Bacteria may be exposed to disinfectant concentrations lower than that required to deliver a lethal insult [28].…”