Comparison of Filters for Concentrating Microbial Indicators and Pathogens in Lake Water Samples

Abstract

Bacterial indicators are used to indicate increased health risk from pathogens and to make beach closure and advisory decisions; however, beaches are seldom monitored for the pathogens themselves. Studies of sources and types of pathogens at beaches are needed to improve estimates of swimming-associated health risks. It would be advantageous and cost-effective, especially for studies conducted on a regional scale, to use a method that can simultaneously filter and concentrate all classes of pathogens from the large volumes of water needed to detect pathogens. In seven recovery experiments, stock cultures of viruses and protozoa were seeded into 10-liter lake water samples, and concentrations of naturally occurring bacterial indicators were used to determine recoveries. For the five filtration methods tested, the highest median recoveries were as follows: glass wool for adenovirus (4.7%); NanoCeram for enterovirus (14.5%) and MS2 coliphage (84%); continuous-flow centrifugation (CFC) plus Virocap (CFC؉ViroCap) for Escherichia coli (68.3%) and Cryptosporidium (54%); automatic ultrafiltration (UF) for norovirus GII (2.4%); and dead-end UF for Enterococcus faecalis (80.5%), avian influenza virus (0.02%), and Giardia (57%). In evaluating filter performance in terms of both recovery and variability, the automatic UF resulted in the highest recovery while maintaining low variability for all nine microorganisms. The automatic UF was used to demonstrate that filtration can be scaled up to field deployment and the collection of 200-liter lake water samples.

Transmission Sources of Waterborne Viruses in South Sudan Refugee Camps

“…The calculated recoveries in the two pre‐acidified water samples were 0.5% in surface water and 1% in household water. These recoveries are similar to the results that have been described in a previous study , indicating that acceptable performance was achieved with respect to the concentration method.…”

Evaluation of Glass Wool Filters and Hollow-Fiber Ultrafiltration Concentration Methods for qPCR Detection of Human Adenoviruses and Polyomaviruses in River Water

“…To determine the recovery efficiency, we seeded raw human wastewater compared to the other studies that seeded cultured viruses obtained from plaque assays (Hill et al 2005;Albinana-Gimenez et al 2009b;Millen et al 2012;Francy et al 2013;Abd-Elmaksoud et al 2014). In real-world scenario, fecal pollution of environmental waters occurs via sewer/septic overflows and surface run off containing fecal matters from various animals.…”

Determining Pathogen and Indicator Levels in Class B Municipal Organic Residuals Used for Land Application

“…Two 40‐mL replicates of the winter sample from Site 5, which had low total solids content, were instead directly analyzed. In all the samples, one replicate was spiked with 400 flow‐sorted (using a FACS Aria; BD Biosciences) Giardia duodenalis (H3) cysts and 400 Cryptosporidium parvum (Harley Moon) oocysts as previously described (Francy et al, 2013). Most of the solids were removed using a modified sedimentation technique (Massanet‐Nicolau, 2003).…”

“…The clarified volumes, containing the cysts and oocysts, were transferred by pipette from the air-water interface to fresh 50-mL conical tubes and the transferred volumes were recorded. Samples were then centrifuged and processed using USEPA Method 1623 as previously described (Francy et al, 2013), with the following modifications: an additional 10-mL wash step during the immunomagnetic separation (IMS) step and a heat dissociation step (10 min at 80°C) were added to the method as described in (Ware et al, 2003). Oocyst and cyst [(oo)cysts] enumeration was done by microscopy as described in USEPA Method 1623, except only the first 30 of the antibody stained (oo)cysts were analyzed by 4¢,6¢-diamidino-2-phenylindole (DAPI) staining and differential interference contrast microscopy (USEPA, 2005).…”