Assessing the Presence of Antibiotic-Resistant Enterococcus in Reclaimed Water Used for Spray Irrigation

Abstract

Reclaiming wastewater is increasing in the US to combat dwindling freshwater supplies. This water potentially contains pathogenic bacteria; therefore, we evaluated the occurrence, concentration, and antimicrobial susceptibilities of Enterococcus spp.--an important opportunistic pathogen that remains a leading cause of nosocomial infections--in reclaimed water used for spray irrigation (SI). A total of 48 wastewater effluent and SI samples were collected in 2009 and 2010 from the Mid-Atlantic and Midwest regions of the US. Enterococci were isolated using membrane filtration, confirmed using biochemical tests and PCR, and tested for antimicrobial susceptibility using the Sensititre® dilution system. We detected total enterococci and vancomycin-resistant enterococci (VRE) in 68% (27/40) and 8% (3/40), respectively, of all SI samples. VRE and vancomycin-intermediate enterococci (VIE) represented 2% (1/41) and 10% (4/41), respectively, of the total enterococci recovered from all SI sites. Our findings show that SI workers may be exposed to enterococci during spray irrigation activities.