BCSE BCSE - Basic and Clinical Sciences Examination Veterinary Microbiology and Infectious Diseases Questions and Answers 2 — Questions and Answers
Question 1: Which antifungal mechanism of action does amphotericin B use to kill fungal cells?
- Binds ergosterol, forming pores that disrupt membrane integrity (Correct answer)
- Inhibits beta-glucan synthase in the cell wall
- Inhibits lanosterol 14-alpha-demethylase
- Blocks fungal DNA gyrase
Correct answer: Binds ergosterol, forming pores that disrupt membrane integrity
Amphotericin B binds ergosterol in the fungal cell membrane and creates transmembrane pores, causing lethal leakage of intracellular ions.
Question 2: Dermatophytosis in cats is most commonly caused by which organism?
- Microsporum canis (Correct answer)
- Trichophyton mentagrophytes
- Microsporum gypseum
- Candida albicans
Correct answer: Microsporum canis
Microsporum canis accounts for approximately 90% of feline dermatophytosis cases and fluoresces apple-green under a Wood's lamp.
Question 3: Which virus causes Marek's disease in poultry and belongs to which family?
- Gallid herpesvirus 2, family Herpesviridae (Correct answer)
- Avian leukosis virus, family Retroviridae
- Newcastle disease virus, family Paramyxoviridae
- Infectious bursal disease virus, family Birnaviridae
Correct answer: Gallid herpesvirus 2, family Herpesviridae
Marek's disease is caused by Gallid herpesvirus 2 (a cell-associated alphaherpesvirus), which induces T-cell lymphomas in susceptible chickens.
Question 4: The zoonotic bacterium Francisella tularensis is most commonly transmitted to humans through which route?
- Arthropod bites (ticks, deer flies) or contact with infected rabbit tissues (Correct answer)
- Fecal-oral contamination from cattle
- Inhalation of bat guano
- Ingestion of undercooked pork
Correct answer: Arthropod bites (ticks, deer flies) or contact with infected rabbit tissues
Tularemia is primarily transmitted via tick or deer fly bites or direct contact with infected lagomorphs, especially rabbits during hunting season.
Question 5: Which serologic test is used as the official screening test for brucellosis in US cattle?
- Rose Bengal plate test (RBPT) or buffered Brucella antigen test (Correct answer)
- Complement fixation test only
- PCR on whole blood
- Milk ring test only
Correct answer: Rose Bengal plate test (RBPT) or buffered Brucella antigen test
The buffered Brucella antigen (Rose Bengal plate) test is the official US screening test for bovine brucellosis in the national eradication program.
Question 6: West Nile virus in horses produces encephalomyelitis and is transmitted primarily by which vector?
- Culex mosquitoes (Correct answer)
- Ixodes ticks
- Simulium black flies
- Culicoides midges
Correct answer: Culex mosquitoes
West Nile virus is an arboviral flavivirus transmitted to horses and humans mainly by Culex species mosquitoes that feed on infected avian reservoir hosts.
BCSE BCSE - Basic and Clinical Sciences Examination Veterinary Microbiology and Infectious Diseases Questions and Answers 2
Which antifungal mechanism of action does amphotericin B use to kill fungal cells?