Methods are needed to quickly detect a variety of biological agents that may be released
into drinking-water supplies through an intentional contamination incident. In the present
study, 13 drinking-water samples were collected from 9 treatment plants to assess the
variability of recoveries of biological agents by culture- or microscopic-based methods and
to determine detections of organisms by quantitative polymerase-chain reaction (qPCR)
after ultrafiltration. Two 100-L subsamples were collected at each site during each
sampling event: one was seeded in the laboratory with target control organisms; and, the
second was used to determine the natural incidence of target organisms and serve as a
negative control. Six waterborne biological agents were targeted, including: Bacillus anthracis
(using B. anthracis Sterne); Burkholderia pseudomallei (using Bu. cepacia as a surrogate);
Francisella tularensis (using F. tularensis Live Vaccine Strain); Salmonella typhi; Vibrio
cholerae; and, Cryptosporidium parvum. Ultrafiltration was used to concentrate all
biological agents simultaneously. Samples were analyzed by qPCR (except for S. typhi)
by cultural methods for bacterial pathogens, and by immunomagnetic
separation/immunofluorescence assay (IMS/FA) microscopy for C. parvum.
Recoveries of biological agents were affected by a variety of factors, including potential
loss of culturability of Burkholderia at lower temperatures, analytical variability of
recoveries between replicate samples, and problems with qPCR reagents. Recoveries by
culture methods for bacteria and IMS/FA for C. parvum were variable between samples
and between some replicate samples, ranging from below detection to greater than 100%.
Recoveries were significantly related to water pH, conductivity, and dissolved organic
carbon (DOC) for culture methods but not for IMS/FA. Recoveries by qPCR were not
calculated because of problems quantifying organisms by qPCR in the composite seed.
Organisms were detected after ultrafiltration by qPCR; only one sample for B. cepacia was
a false negative by qPCR in regard to the cultural or IMS/FA method. Numbers found by
qPCR after ultrafiltration were significantly related or nearly related to numbers found by
the culture methods for B. anthracis, F. tularensis, and V. cholerae but not for Bu. cepacia
and C. parvum. Includes 13 references, tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 820 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 11/01/2008 |
