Brain heart infusion broth may not be a required component for the decontamination process for the isolation of Mycobacterium avium subspecies Paratuberculosis from fecal samples using ESP broth cultures.
Based on the authors' laboratory experience indicating that increased bacterial contamination in Mycobacterium avium ssp. paratuberculosis (MAP) cultures may be because of the addition of brain heart infusion broth (BHI) during the decontamination process, this study was designed to examine whether BHI is a required component for the isolation of MAP from ESP(R) broth cultures. Twenty-six National Veterinary Services Laboratory (NVSL) proficiency test samples supplied for the year 2005 were used for the comparison. Two paired sets of samples were processed in the experiment. In one set, the hexadecylpyridinium chloride monohydrate (HPC) and antibiotic brew were prepared in half strength BHI and for the other set, HPC and antibiotic brew were prepared in sterile distilled water. Culture of the 26 samples using the BHI/HPC decontamination method identified 13 (50%) positives, whereas culture using the water/HPC decontamination method identified 14 (54%) positives. The proportions of samples with a positive result did not differ significantly between the 2 decontamination methods. Although in most cases it took longer to identify a positive result by the BHI method, the difference between methods with respect to the number of days to a positive culture result was not statistically significant. Retrospective data collected from the Animal Disease Diagnostic Laboratory, Ohio also suggest that inclusion of BHI in the decontamination protocol may not have any effect on MAP recovery or contamination rate. Elimination of BHI from broth cultures may increase the sensitivity of MAP isolation, and reduce the cost of testing.
Rajeev
Sreekumari
S
University of Georgia, Veterinary Diagnostic and Investigational Laboratory, 43 Brighton Road, Tifton GA 31793, USA. srajeev@uga.edu
Berghaus
Roy D
RD
Johnson
Jill
J
Pence
Mel
M
Byrum
Beverly
B
Farrell
Troy
T
Baldwin
Charles
C
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000382:microbiology; D003470:Culture Media / Q000737:chemistry*; D005243:Feces / Q000382:microbiology*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D010283:Paratuberculosis / Q000175:diagnosis / Q000382:microbiology
D003470:Culture Media