Evaluation of the Assurance GDS® for Salmonella Method in Foods and Environmental Surfaces: Multilaboratory Collaborative Study

A multilaboratory collaborative study was conducted to compare the detection of Salmonella by the Assurance GDS® for Salmonella method and the Reference culture methods. Six foods, representing a variety of low microbial and high microbial load foods were analyzed. Seventeen laboratories in the United States and Canada participated in this study. No statistical differences (P < 0.05) were observed between the Assurance GDS for Salmonella and the Reference culture methods for any inoculation level of any food type or naturally contaminated food, except for pasta, for which the Assurance GDS method had a higher number of confirmed test portions for Salmonella compared to the Reference method.

Evaluation of the Assurance GDS™ for E. coli O157:H7 Method and Assurance GDS for Shigatoxin Genes Method in Selected Foods: Collaborative Study

A multilaboratory collaborative study was conducted to compare the Assurance GDS™ for E. coli O157:H7 method and the reference culture methods for the detection of E. coli O157:H7 in orange juice, raw ground beef, and fresh lettuce. A separate companion assay, the Assurance GDS for Shigatoxin Genes method was also evaluated with the same test portions. Fifteen laboratories participated in the study. A Chi square analysis of each of the 3 food types at the high, low, and uninoculated control levels was performed. For all foods, the Assurance GDS for E. coli O157:H7 method and the Assurance GDS for Shigatoxin Genes method were equivalent to or better than the reference methods.

Evaluation of the Assurance GDS for Salmonella method in foods and environmental surfaces: multilaboratory collaborative study

A multilaboratory collaborative study was conducted to compare the detection of Salmonella by the Assurance GDS for Salmonella method and the Reference culture methods. Six foods, representing a variety of low microbial and high microbial load foods were analyzed. Seventeen laboratories in the United States and Canada participated in this study. No statistical differences (P < 0.05) were observed between the Assurance GDS for Salmonella and the Reference culture methods for any inoculation level of any food type or naturally contaminated food, except for pasta, for which the Assurance GDS method had a higher number of confirmed test portions for Salmonella compared to the Reference method.

Evaluation of the assurance GDS for E. coli O157:H7 method and assurance GDS for shigatoxin genes method in selected foods: collaborative study

A multilaboratory collaborative study was conducted to compare the Assurance GDS for E. coli 0157:H7 method and the reference culture methods for the detection of E. coli 0157:H7 in orange juice, raw ground beef, and fresh lettuce. A separate companion assay, the Assurance GDS for Shigatoxin Genes method was also evaluated with the same test portions. Fifteen laboratories participated in the study. A Chi square analysis of each of the 3 food types at the high, low, and uninoculated control levels was performed. For all foods, the Assurance GDS for E. coli O157:H7 method and the Assurance GDS for Shigatoxin Genes method were equivalent to or better than the reference methods.

Characterization of the haemorrhagic enteritis virus genome and the sequence of the putative penton base and core protein genes

Haemorrhagic enteritis virus (HEV) is a member of a genetically ill-defined group within the genus Aviadenovirus which causes significant clinical disease in gallinaceous fowl. Using DNA obtained from a low virulence isolate of HEV passed in turkeys, we developed a genomic restriction map and estimated an apparent genomic length of 25.5 kb. No evidence for extensive DNA hybridization was found between the HEV genome and either the hexon or penton base genes of human adenovirus 2 (HAdV-2) and fowl adenovirus 10 (FAdV-10). The HEV penton base gene was identified by PCR using primers based on conserved adenoviral DNA sequences. The penton base gene was expressed in Escherichia coli as a fusion protein and detected by anti-HEV serum in both colony and denaturing gel immunoblots. DNA sequencing revealed a putative penton base ORF with a predicted amino acid sequence showing approximately 39.0%, 53.0% and 44.2% similarity with the penton base of HAdV-2, human adenovirus 40 (HAdV-40) and FAdV-10, respectively. The penton base gene was located at 43.3-48.6 m.u. on the HEV genome and had a remarkably low G+C content (33.8%). DNA sequencing also revealed ORFs for putative core proteins resembling pVII, p-mu and a partial ORF similar to pVI (hexon-associated protein) of HAdV-2 and HAdV-40. The results support the claim that HEV represents a distinct group of viruses within the genus Aviadenovirus.

Epidemiology of infection by nontuberculous mycobacteria IX. Evidence for two DNA homology groups among small plasmids in Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum

A 12.9 kb plasmid, pVT2, from a clinical Mycobacterium avium isolate, MD1, was cloned and radiolabeled for use as a DNA probe to examine the relatedness of plasmids in M. avium complex. That probe hybridized with plasmids isolated from M. avium complex strains from the environment (7 of 16) and from non-acquired immunodeficiency syndrome (AIDS) (10 of 17) and AIDS (5 of 6) clinical isolates. The similarity of plasmids from the environment with those from patients supports the hypothesis that the environment is a source of human M. avium complex infection. More striking was the observation that pVT2 hybridized with every plasmid (13 of 13 clinical and 5 of 5 environmental isolates) of 13.5 kb or smaller. A second probe, consisting of a 15.3 kb plasmid (pLR7) from another clinical isolate of the M. avium complex, hybridized with plasmids of 15.3 to 25 kb from environmental and clinical (AIDS and non-AIDS) isolates. There was no hybridization between pVT2 and pLR7. Thus, these two probes define two different groups of small mycobacterial plasmids.