Greater Number Of Positive Samples Research Articles

Comparison of VIDAS enzyme-linked fluorescent immunoassay using Moore swab sampling and conventional culture method for Salmonella detection in bulk tank milk and in-line milk filters in California dairies

A comparison of the VIDAS Salmonella (SLM) assay using the manufacturer's recommended sampling method or a Moore swab sampling method demonstrated that the Moore swab method detected a greater number of positive samples (83.0% vs. 67.92%). When results using a conventional culture technique were compared to the VIDAS SLM assay using Moore swab sampling, there was good agreement (97.5%). When the VIDAS SLM assay was used to test in-line milk filters and compared to results from the conventional culture method, there was also good correlation between test results (95.57%). Overall, the VIDAS SLM assay using a modified sampling method compared favorably to the conventional culture method and had the advantages of taking less time to obtain a negative or presumptive positive result, being less technically complicated and requiring less screening of non-lactose fermenting colonies from negative samples.

Use of ELISA and isolation for determining the distribution of Rhizoctonia solani and other Rhizoctonia spp. in asymptomatic creeping bentgrass

A commercial Rhizoctonia-specific ELISA was compared with isolation on antibiotic-amended water agar for the detection of Rhizoctonia solani and other Rhizoctonia spp. in asymptomatic creeping bentgrass near active brown patch disease centres. A greater number of positive samples were indicated by ELISA than by isolation in tests of foliage and root tissues. Over 75% agreement was found between ELISA and isolation with foliage, but the presence of Rhizoctonia spp. in root tissues could not be confirmed by isolation from any of the ELISA-positive samples. There was poor agreement between the two methods in assays of organic matter from thatch. Greater numbers of thatch samples were positive for Rhizoctonia spp. by isolation than by ELISA. Pathogenic R. solani was found by both methods in asymptomatic foliage as far as 30 cm from the margins of brown patch disease areas. There was a more restricted distribution of the fungus in the thatch. Detection of the fungus in root tissues from asymptomatic areas by ELISA could not be confirmed by isolation.

Evaluation of Direct Enrichment at Elevated Temperature for Recovery of Salmonellae from Oysters

A comparison of the recovery of salmonellae from naturally contaminated oysters was made by using either Lactose broth preenrichment at 35°C followed by selective enrichment in Tetrathionate and Selenite Cystine broths at 35, 41 and 43°C, or direct enrichment in Tetrathionate and Selenite Cystine broths with incubation at 35, 41 and 43°C. Direct enrichment in Selenite Cystine broth at both elevated temperatures produced the greatest number of positive samples. Similar results were obtained with artificially contaminated oyster samples (1 Salmonella/5 g of meat). Statistical analysis of the data showed that significantly higher recovery of salmonellae was obtained by using direct enrichment of samples in Selenite Cystine broth at the elevated temperature.

Enzyme-immunoassay in the detection of hepatitis B surface antigen

A new enzyme-immunoassay (EIA, Hepanostika Microelisa System) for the detection of hepatitis B surface antigen was evaluated against other methods, namely complement fixation, Hepanosticon, AusRIA II and Finnish Red Cross Radioimmunoassay (FRC-RIA). EIA detected the greatest number of positive samples in a serum panel consisting of 142 sera from clinical hepatitis patients. FRC-RIA was the most sensitive method for subtype ad, while EIA detected the ay specimen at the highest dilution. None of the test systems gave the ‘optimal’ result in the screening test, and it is prpposed that a separate procedure for each antigen subtype should be carried out to detect the greatest number of positive samples.

Demonstration and isolation of Clostridium botulinum types from whitefish chubs collected at fish smoking plants of the Milwaukee area.

A total of 1,071 whitefish chub samples were examined at eight stages of processing, including sampling aboard ship, various processing steps in the smoking plant, and display in retail cases. The frequency of Clostridium botulinum contamination of freshly caught and eviscerated chubs was approximately 13 to 14%. The highest percentage of contamination (20%) was noted among chubs sampled at the brining step of processing. The prevalence of contamination among chubs sampled at other processing stages prior to the smoking operation ranged from 6 to 14%. Of 858 freshly smoked chubs that had been processed at 180 F for 30 min (internal temperature of loin muscle), 10 were contaminated with C. botulinum (1 Type B and 9 Type E). The use of heat-shocked (60 C for 15 min) and nonheat-shocked enrichment cultures in combination yielded a greater number of positive samples than either method yielded when used alone. Each toxic enrichment culture obtained was subcultured to obtain isolation of the toxigenic organism. Toxigenic pure cultures of C. botulinum were obtained from 80% of the fish samples observed to produce toxic enrichment cultures.

Demonstration and Isolation of Clostridium botulinum Types from Whitefish Chubs Collected at Fish Smoking Plants of the Milwaukee Area

A total of 1,071 whitefish chub samples were examined at eight stages of processing, including sampling aboard ship, various processing steps in the smoking plant, and display in retail cases. The frequency of Clostridium botulinum contamination of freshly caught and eviscerated chubs was approximately 13 to 14%. The highest percentage of contamination (20%) was noted among chubs sampled at the brining step of processing. The prevalence of contamination among chubs sampled at other processing stages prior to the smoking operation ranged from 6 to 14%. Of 858 freshly smoked chubs that had been processed at 180 F for 30 min (internal temperature of loin muscle), 10 were contaminated with C. botulinum (1 Type B and 9 Type E). The use of heat-shocked (60 C for 15 min) and nonheat-shocked enrichment cultures in combination yielded a greater number of positive samples than either method yielded when used alone. Each toxic enrichment culture obtained was subcultured to obtain isolation of the toxigenic organism. Toxigenic pure cultures of C. botulinum were obtained from 80% of the fish samples observed to produce toxic enrichment cultures.

Comparison of methods of examining stools for parasites.

Summary Simultaneous fecal examinations were made of 400 samples by the following methods: direct, Faust, Bayona, Ferreira and Baermann; 103 samples were negative and in the remainder, 18 species of parasites were found. The direct method is indispensable for the finding of trophozoites. For cysts, eggs and larvae, the Ferreira method diagnosed a greater number of positive samples than the other methods. It was particularly effective when the number of eggs was small, providing richer concentrations. However, irregularity of excretion, particularly of cysts, makes more than one examination necessary.