Jokinen C.C.,Public Health Agency of Canada |
Koot J.M.,Public Health Agency of Canada |
Carrillo C.D.,Sir Fg Banting Research Center |
Gannon V.P.J.,Public Health Agency of Canada |
And 4 more authors.
Journal of Microbiological Methods | Year: 2012
Improved isolation techniques from environmental water and animal samples are vital to understanding Campylobacter epidemiology. In this study, the efficiency of selective enrichment in Bolton Broth (BB) followed by plating on charcoal cefoperazone deoxycholate agar (CCDA) (conventional method) was compared with an approach combining BB enrichment and passive filtration (membrane method) adapted from a method previously developed for testing of broiler meat, in the isolation of thermophilic campylobacters from surface water and animal fecal samples. The conventional method led to recoveries of Campylobacter from 36.7% of the water samples and 78.0% of the fecal samples and similar numbers, 38.3% and 76.0%, respectively, were obtained with the membrane method. To investigate the genetic diversity of Campylobacter jejuni and Campylobacter coli obtained by these two methods, isolates were analyzed using Comparative Genomic Fingerprinting, a high-resolution subtyping technique. The conventional and membrane methods yielded similar numbers of Campylobacter subtypes from water (25 and 28, respectively) and fecal (15 and 17, respectively) samples. Although there was no significant difference in recovery rates between the conventional and membrane methods, a significant improvement in isolation efficiency was obtained by using the membrane method, with a false-positive rate of 1.6% compared with 30.7% obtained using the conventional method. In conclusion, although the two methods are comparable in sensitivity, the membrane method had higher specificity, making it a cost-effective procedure for the enhanced isolation of C. jejuni and C. coli from water and animal fecal samples. © 2012.
Gill A.,Sir Fg Banting Research Center |
O. Gill C.,Agriculture and Agri Food Canada
Canadian Journal of Veterinary Research | Year: 2010
Verotoxigenic Escherichia coli (VTEC) are important foodborne pathogens in Canada. VTEC of the O157:H7 serogroup have been the focus of regulatory action and surveillance in both Canada and the USA, due to their role in a number of high profile outbreaks. However, there is increasing evidence that other VTEC serogroups cause a substantial proportion of human illness. This issue is of particular importance to the cattle industry due to the role of beef as a vehicle for VTEC transmission. In this review, the evidence for non-O157 VTEC as cause of human illness in Canada and the potential for Canadian beef and cattle to serve as a source of VTEC are presented. In addition, the available strategies for the control of VTEC in cattle and beef are discussed.
Ganz K.,Sir Fg Banting Research Center |
Gill A.,Sir Fg Banting Research Center
Food Microbiology | Year: 2013
The aim of this study was to determine whether Escherichia coli O157:H7 can be reliably detected and isolated from walnut kernels using standard methods of analysis. The limit of detection approached 1 cell per analytical unit (25 g) for E. coli O157:H7 on walnut kernels enriched in modified tryptic soy broth with 20 μg/ml novobiocin and plating onto selective agar media. The presence of PCR inhibitors in walnut kernels was indicated by the failure to detect E. coli O157:H7 from culture positive enrichment broths analysed by PCR, with two separate polymerase and reagent compositions (Dupont BAX E. coli O157:H7 MP system, Promega GoTaq Green for stx) and three methods of template preparation (DuPont BAX, Qiagen DNeasy, Bio-Rad InstaGene). PCR inhibition was overcome by 1:100 dilution in TE buffer of the DNeasy or InstaGene template. PCR inhibition was not relieved by dilution of the BAX template. Similar results were observed for walnut kernels inoculated with Salmonella enterica and analysed for invA, indicating that PCR inhibition is not specific to the organism or primer/template. These results indicate that analysis of walnut kernels for pathogens should be with culture based methods or use protocols for DNA template preparation modified to remove or dilute inhibitors and the need for internal amplification controls in PCR methods. © 2013 .