STANDARDIZATION OF A FIELD TEST FOR THE DIAGNOSIS OF ANTHRAX IN LIVESTOCK
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Date
2018-11
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
The present study reports the isolation and characterization of Bacillus anthracis
and standardization of a field test for the diagnosis of anthrax in livestock. Thirteen
isolates were recovered from seventeen carcasses, suspected of anthrax. Colony
morphology showed typical ‘curled hair’ or ‘medusa head’ appearance. Gram’s staining
revealed Gram- positive rods which appeared in pairs or short chains, giving a ‘box car’
or ‘jointed bamboo-rod’ appearance. All the isolates were positive to Voges- Proskauer
and nitrate reduction tests, non haemolytic on blood agar, did not grow on Mac Conkey
agar and were sensitive to penicillin. All thirteen isolates yielded amplified products of
596 bp specific for pag gene and 846 bp amplicon specific for cap gene using PCR.
Latex agglutination test was standardized using polyclonal antibodies. The LAT was
positive B. anthracis field isolates (+++). The diagnostic sensitivity revealed that a
minimum of 2.15×104 CFU/ml of B. anthracis bacilli was adequate to elicit a definite
agglutination. Further the diagnostic specificity of LAT was so efficient that, it did not
produce any false positive reactions with eleven other bacterial species tested even at
1000 times more bacterial cells than the B. anthracis. So the standardization of LAT for
the rapid, sensitive and specific identification of B. anthracis is an invaluable tool for the
field diagnosis of anthrax.