Multistate Evaluation of an Ultrafiltration-Based Procedure for Simultaneous Recovery of Enteric Microbes in 100-Liter Tap Water Samples

Abstract

Ultrafiltration (UF) is increasingly being recognized as a potentially effective procedure for concentrating and recovering microbes from large volumes of water and treated wastewater. Because of their very small pore sizes, UF membranes are capable of simultaneously concentrating viruses, bacteria, and parasites based on size exclusion. In this study, a UF-based water sampling procedure was used to simultaneously recover representatives of these three microbial classes seeded into 100-liter samples of tap water collected from eight cities covering six hydrologic areas of the United States. The UF-based procedure included hollow-fiber UF as the primary step for concentrating microbes and then used membrane filtration for bacterial culture assays, immunomagnetic separation for parasite recovery and quantification, and centrifugal UF for secondary concentration of viruses. Water samples were tested for nine water quality parameters to investigate whether water quality data correlated with measured recovery efficiencies and molecular detection levels. Average total method recovery efficiencies were 71, 97, 120, 110, and 91% for X174 bacteriophage, MS2 bacteriophage, Enterococcus faecalis, Clostridium perfringens spores, and Cryptosporidium parvum oocysts, respectively. Realtime PCR and reverse transcription-PCR (RT-PCR) for seeded microbes and controls indicated that tap water quality could affect the analytical performance of molecular amplification assays, although no specific water quality parameter was found to correlate with reduced PCR or RT-PCR performance.

Rapid dead-end ultrafiltration concentration and biosensor detection of enterococci from beach waters of Southern California

“…Mean recovery efficiencies for each site and time point ranged from 37% to 195% with an overall average of 107%. Recoveries over 100% have been reported by others performing hollow fibre ultrafiltration of known spiked amounts of the target microbes (Hill et al 2005(Hill et al , 2007Polaczyk et al 2008), as well as previously in Florida using this procedure (Leskinen & Lim 2008). …”

Comparison of real-time PCR methods for the detection of Naegleria fowleri in surface water and sediment

“…DNA was extracted from ameba stock cultures using a lysis buffer (Phthisis Diagnostics/Microbiologics, catalog #E003-100) containing 4.5 M guanidinium isothiocyanate (Hill et al 2007, 2010). Briefly, 700 μL of lysis buffer was added to 700 μL of harvested ameba in a 2-mL screw-cap polypropylene tube (National Scientific Supply, Claremont, CA) that contained 200 mg each of 0.2- and 0.5-mm acid-washed ZrOx beads.…”

Microbial and chemical contamination during and after flooding in the Ohio River—Kentucky, 2011

“…[19] Enterococci were enumerated by Enterolert (IDEXX Laboratories). Salmonella was detected by membrane filtration using 0.45-µm mixed-cellulose ester filters, followed by broth and agar culture according to Hill and Sobsey, [20] and PCR using the TaqMan assay of Hill et al [21] E. coli O157:H7 was also assayed by culture and real-time PCR. [22] …”