Journal - Veterinary microbiology (Netherlands )

Abstract :

A goal of Johne's disease control programs is to accurately detect Mycobacterium avium ssp. paratuberculosis (MAP) infected cattle as quickly as possible to reduce disease transmission. A newly introduced real-time PCR provides results rapidly, but its accuracy in the field has not been evaluated. Fecal and serum samples collected from dairy cows in northern Indiana were used to estimate the sensitivity and specificity of a newly licensed real-time PCR test for direct fecal detection of Mycobacterium avium ssp. paratuberculosis (MAP). Results of the real-time PCR were evaluated in parallel with solid and liquid media culture systems and a serum ELISA for detection of MAP antibodies to determine the accuracy of the real-time PCR and the tests' potential usefulness in the field. A total of 143 samples were tested by all four methods. Using prior published estimates for sensitivity and specificity of each of the tests and Bayesian methodology, the sensitivity and specificity of the real-time PCR test was estimated to be 0.60 and 0.97, respectively. The accuracy of real-time PCR (0.90) was comparable to both solid (0.91) and liquid (0.93) culture. Because real-time PCR accuracy is comparable to standard culture methods, it is a useful new test. In addition, test results are obtained as rapidly as an ELISA, but are more accurate than the ELISA (0.82). This makes real-time PCR an attractive test and should shorten the quarantine period required for new purchases of unknown MAP-status animals into herds participating in an MAP control program.

Journal - The Veterinary record (England )

Journal - Preventive veterinary medicine (Netherlands )

Abstract :

Detection methods for Mycobacterium avium subsp. paratuberculosis (MAP) are imperfect, yet crucial for diagnosis of Johne's disease. Our purpose was to test for significant and biologically relevant changes in Johne's ELISA results associated with how field-collected blood samples were transported to the laboratory, prepared and stored prior to testing, while removing potential confounding by test kit and laboratory variables. Blood samples were collected from 21 cows that previously had MAP ELISA scores ranging from negative to highly positive. Samples for immediate laboratory processing were subjected to different transportation temperatures (on ice, 26 degrees C) and preparation methods (serum separated, hemolyzed and serum separated, clotted whole blood), but were tested using the same ELISA kit in the same laboratory. Samples for laboratory processing after one week of storage were subjected to different storage temperatures (4 degrees C, -20 degrees C) and preparation methods (serum separated, hemolyzed and serum separated, clotted whole blood), and again were tested using the same ELISA kit in the same laboratory. Finally, samples were evaluated by time to processing (one day, one week) and storage temperature (4 degrees C, -20 degrees C). Data were checked for normality and analyzed with repeated measures ANOVAs. Significantly (P=0.027) higher MAP ELISA scores were recorded for whole blood and hemolyzed samples transported at 26 degrees C than serum separated samples. Sample storage for one week at -20 degrees C resulted in significantly (P<0.001) lower MAP ELISA scores, regardless of handling method, compared to samples stored at 4 degrees C for one week. Method of sample preparation, as well as transportation temperature and medium-term storage temperature, affects MAP ELISA results. Such discrepancies will inevitably result in improper classification of MAP-infected cattle, impeding both biosecurity measures on uninfected farms and MAP control programs.

Journal - Preventive veterinary medicine (Netherlands )

Abstract :

Identification of risk factors for horses shedding Salmonella in their feces helps identify patients at-risk of infection and protect the overall population through heightened biosecurity. Fecal samples from 230 hospitalized horses were cultured for Salmonella spp. Historical data were collected on 21 putative risk factors and assessed for association with the risk of a horse being culture positive using forwards stepwise logistic regression. Salmonella was isolated from 13 horses--most commonly from either the first (n=5) or second (n=4) sample collected. Only presenting complaint (confounded by age, breed and gender) was significantly (P < or = 0.05) associated with positive Salmonella-culture results. Analysis of residuals showed that the model was robust, but individual risk-factor estimates were changed by removal of outliers. Overall, presenting complaint (for example, lower-respiratory-tract disease) was the most important indicator of culture status.

Journal - Journal of the American Veterinary Medical Association (United States )

Abstract :

OBJECTIVES: To assess methods of detecting environmental contamination with Salmonella organisms and evaluate a cleaning and disinfection protocol for horse stalls in a veterinary teaching hospital. DESIGN: Original study. SAMPLE POPULATION: 37 horses with diarrhea likely to be caused by Salmonella infection and their stall environments. PROCEDURES: Fecal samples were collected from horses daily during hospitalization; samples were obtained from stall sites after cleaning and application of disinfectants. Fecal and environmental samples were cultured for Salmonella spp and tested via polymerase chain reaction (PCR) assay to detect Salmonella DNA. RESULTS: 1 horse died and 2 were discharged prior to sample collection. Fecal samples from 9 of 34 horses yielded growth of Salmonella organisms on bacteriologic culture, and 23 yielded positive results via PCR assay on > or = 1 occasion. Among environmental samples from 21 stalls, salmonellae were detected at > or = 1 stall site on 6 of 78 occasions, and > or = 1 stall site yielded positive results via PCR assay on 69 of 77 occasions. Salmonella DNA was detected more frequently in samples of stall drains, cracks, and corners. Salmonella spp were cultured from samples of 3 stalls after both initial and second cleaning and disinfection cycles, but no organisms were detected in samples obtained after use of a peroxygen disinfectant. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that stalls in which horses with salmonellosis were housed should only be used to accommodate newly hospitalized horses after samples (collected after 2 cycles of cleaning and disinfection) from drains, cracks, and corners yield negative results on bacteriologic culture.