Gram Positive Bacilli
All are true about Bacillus except (AIIMS Nov 2010)
|A||Mc Fadyean’s reaction is used in presumptive diagnosis of anthrax infection|
|B||Medusa head appearance of colonies in gelatin stab culture|
|C||PLET is the selective medium|
|D||Ascoli’s thermpoprecipitation test is used for laboratory diagnosis|
Medusa head appearance of colonies in gelatin stab culture
a. Medusa head colonies are seen on agar plate culture because of chains of bacilli while inverted fir tree appearance is seen in gelatin stab culture.
b. Selective medium for bacillus is Polymyxin-lysozyme-EDTA-thallous acetate medium.
c. Blood films of infected animals on staining with polychrome methylene blue show an amorphous purplish material around the chains of bacilli. This is called Mc Fadyean’s reaction.
d. Ascoli’s thermoprecipitation test is a ring precipitation test used in older times to detect the antigen of B. anthracis in tissue extracts.