National Licensure Examination for Veterinarians (NLEV) · Nepal · Nepal Veterinary Council (NVC Act 2055 BS)
Original practice questions written to the published syllabus · not past papersThe bacteria and fungi that cause disease in animals, genus by genus: what they are, where they live, what they cause and how they are identified.
In the exams: ICAR AICE-JRF core group 06; ICAR AIEEA-PG 13 (Microbiology); China preventive paper
How our questions for National Licensure Examination for Veterinarians spread across the units of Systematic Veterinary Bacteriology & Mycology. Difficulty: 14 easy, 25 medium, 0 hard.
| Streptococcus | 3 | |
| Clostridium | 3 | |
| Mycobacterium: tuberculosis and Johne's disease | 3 | |
| Brucella | 3 | |
| Salmonella | 3 | |
| Leptospira | 3 | |
| Rickettsia and Chlamydia | 3 | |
| Dermatophytes | 3 | |
| Aspergillus and Candida | 3 | |
| Pasteurella and Mannheimia | 2 | |
| Escherichia coli | 2 | |
| Listeria | 2 | |
| Burkholderia mallei (glanders) | 2 | |
| Mycoplasma | 2 | |
| Staphylococcus | 1 | |
| Bacillus anthracis | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
On sheep blood agar, a mastitis isolate shows an inner zone of complete clearing surrounded by a wider zone of incomplete haemolysis. Which organism is this classic for?
A. Staphylococcus aureus, through alpha- and beta-toxins
Many S. aureus strains produce double-zone haemolysis: alpha-toxin gives the inner complete zone and beta-toxin the outer incomplete zone. The CAMP factor of S. agalactiae causes no haemolysis on its own; it only enhances staphylococcal beta-toxin in the CAMP test. S. uberis is usually non-haemolytic or alpha-haemolytic.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
On Edwards medium a bovine mastitis streptococcus grows as dark colonies because it hydrolyses aesculin. Which species is most likely?
D. Streptococcus uberis, an environmental pathogen
S. uberis hydrolyses aesculin and gives dark colonies on Edwards medium; S. agalactiae and S. dysgalactiae are aesculin negative. S. equi is not a bovine mastitis pathogen.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
Weaned pigs show paddling, opisthotonos and sudden death, and a pig farmer later develops meningitis with hearing loss. Which organism links the two?
C. Streptococcus suis serotype 2
S. suis, classically serotype 2, causes meningitis, arthritis and septicaemia in weaners and is a zoonosis of people handling pigs and pork, with meningitis and deafness. Glaesserella (Haemophilus) parasuis causes polyserositis and meningitis in pigs but is not a zoonosis; F18 E. coli causes oedema disease with neurological signs but not human meningitis.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
A cow is found dead with dark, unclotted blood oozing from the nostrils and anus. What should the veterinarian do first?
C. Take a blood smear from an ear vein and keep the carcass unopened
The picture suggests anthrax. Opening the carcass exposes the bacilli to air, so they sporulate and contaminate the site for decades; the diagnosis is made from a peripheral blood smear stained by the M'Fadyean method. Moving the carcass spreads contamination; treating in-contacts may be part of control, but not with a necropsy afterwards.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
Which Salmonella serovar is host-adapted to cattle and causes abortion and long-term carriers in adult cows?
C. Dublin
S. Dublin is adapted to cattle and causes enteritis, septicaemia, abortion and persistent carriage. Choleraesuis is adapted to pigs, Abortusovis to sheep, and Pullorum to poultry.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
Chicks under three weeks old die in large numbers with white, pasty diarrhoea, and the infection is traced to the breeder flock. The organism is:
B. Salmonella Pullorum
Pullorum disease (bacillary white diarrhoea) is caused by S. Pullorum, which is transmitted through the egg and kills young chicks. Breeder flocks are tested by plate agglutination and reactors removed. S. Typhimurium is not host-adapted and less often causes this pattern.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
Which Salmonella serovar can colonise the reproductive tract of laying hens and contaminate the contents of eggs without making the hens ill?
D. Enteritidis
S. Enteritidis infects the ovary and oviduct and contaminates egg contents while hens stay healthy, which makes it a major food-borne zoonosis. S. Gallinarum causes fowl typhoid, a severe disease of the birds themselves.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
Leptospires are best seen alive in a fresh sample using:
C. Dark-field microscopy
Leptospires are very thin and stain poorly with Gram stain, so live organisms are seen as motile, coiled, hooked spirochaetes by dark-field microscopy; silver stains or immunohistochemistry are used in tissue. India ink shows the capsule of Cryptococcus.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
A goat dies after showing circling. Which sample and lesion best confirm encephalitic listeriosis?
C. Brainstem, showing microabscesses and perivascular cuffing
Listeria causes rhombencephalitis, and the brainstem (medulla and pons) shows microabscesses with perivascular cuffing; it is also the sample for culture. Laminar cortical necrosis is polioencephalomalacia, and a pulpy kidney with glycosuria is type D enterotoxaemia.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
White, raised plaques with a 'Turkish towel' appearance on the crop mucosa of poultry after prolonged antibiotic treatment indicate:
A. Candidiasis (crop mycosis)
Candida albicans overgrows when antimicrobials disturb the normal flora and produces thick white plaques on the crop. Aspergillus affects the respiratory tract; trichomoniasis and diphtheritic pox produce caseous lesions mainly in the mouth and upper digestive tract and are not linked to antibiotic use.
Further reading: Quinn et al., Veterinary Microbiology and Microbial Disease; WOAH Terrestrial Manual
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