BCSE - Basic and Clinical Sciences Examination Veterinary Microbiology and Infectious Diseases Questions and Answers Flashcards

Which bacterial pathogen is the most common cause of leptospirosis in dogs in the United States?

Answer: Leptospira interrogans serovars Canicola and Icterohaemorrhagiae

Leptospira interrogans serovars Canicola and Icterohaemorrhagiae are the serovars most frequently associated with leptospirosis in US dogs.

Parvovirus type 2 in dogs primarily damages which tissue to cause hemorrhagic enteritis?

Answer: Intestinal crypt epithelium

Canine parvovirus-2 targets rapidly dividing intestinal crypt epithelial cells, destroying the mucosal renewal mechanism and leading to hemorrhagic enteritis.

Which organism causes 'Potomac horse fever' (equine monocytic ehrlichiosis) in the United States?

Answer: Neorickettsia risticii

Neorickettsia risticii (formerly Ehrlichia risticii) is the causative agent of Potomac horse fever, transmitted via ingestion of infected aquatic insects.

The Gram stain appearance of Clostridium perfringens from a culture is best described as:

Answer: Large Gram-positive rods with subterminal spores

Clostridium perfringens appears as large, boxcar-shaped Gram-positive rods, typically with subterminal (rarely terminal) endospores.

Which test is considered the 'gold standard' for diagnosis of Johne's disease (paratuberculosis) in cattle?

Answer: Fecal culture for Mycobacterium avium subsp. paratuberculosis

Fecal culture for Mycobacterium avium subsp. paratuberculosis remains the gold standard, though it requires 8–16 weeks of incubation.

Feline infectious peritonitis (FIP) is caused by a mutated form of which virus?

Answer: Feline enteric coronavirus

FIP arises when feline enteric coronavirus mutates to a highly pathogenic biotype that infects and replicates within macrophages, causing systemic vasculitis.