11. An enrichment medium for the isolation of Shigella is
A. Alkaline peptone water
B. Terathionate broth
C. Selenite F broth
D. none of these
12. In the Widal test, the significant titers for H agglutinins is
A. 1:50 or more
B. 1:100 ormore
C. 1:200 or more
D. 1:400 or more
13. Heat-labile enterotoxin of Escherichia coli activates
A. guanylate cyclase
B. adenylate cyclase
C. both (a) and (b)
D. none of these
14. Heat-stable enterotoxin of Escherichia coli activates
A. adenylate cyclase
B. guanylate cyclase
C. both of the above
D. none of these
15. The bacteria that is negative for fermentation of mannitol is
A. S flexneri
B. S boydii
C. S dysenteriae
D. S sonnei