Veterinary Microbiology- ICAR JRF/SRF 2024

• Distinctive Anatomy of the Genus Chrysops:
• Female deer flies (Chrysops spp., family Tabanidae):
• Distinctive wing pigmentation: A dark brown coastal margin and a conspicuous wide transverse pigmented band crossing from the anterior to the posterior wing border.
• Abdomen: Prominent yellow/orange coloration with characteristic 'U'-shaped or inverted 'V'-shaped dark dorsal stripes extending from the second to fourth abdominal segments.
• Slender antennae with long cylindrical segments.
• nalysis:
• (Chrysops spp): Correct.

Correct option: (4) Chrysops spp

• Substituted Phenols in Veterinary Medicine:
• Substituted phenolic anthelmintics act by uncoupling oxidative phosphorylation in helminth mitochondria:
• Bithionol: Dichlorophenolic compound.
• Hexachlorophene: Bisphenol derivative.
• Nitroxynil: Substituted monophenol ($4\text{-hydroxy-3-iodo-5-nitrobenzonitrile}$).
• Niclosamide:
• chlorinated Salicylanilide derivative (5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide), not classified chemically as a simple substituted phenol.
• nalysis:
• (Niclosamide): Correct.

Correct option: (3) Niclosamide

• Antimicrobial Constituents of Bovine Milk:
• Lactoferrin: Iron-binding glycoprotein that exerts bacteriostatic effects by sequestering free ferric ions ($Fe^{3+}$) required for bacterial growth.
• Lactoperoxidase: Combines with thiocyanate and $H_2O_2$ to generate antibacterial hypothiocyanite ($OSCN^-$).
• Secretory IgA (sIgA): Major mucosal immunoglobulin that neutralizes pathogens and blocks epithelial adherence.
• Somatic Leucocytes: Neutrophils, macrophages, and lymphocytes that phagocytose and destroy invading bacteria in the mammary gland.
• nalysis:
• All four components contribute to milk defense. Hence, Option 1 ((A), (B), (C) and (D)) is correct.

• Bacteria Shed Internally in Milk:
• Contamination of milk can arise from environmental exterior sources or directly from the interior of infected mammary tissue:
• Brucella abortus (B): Localizes chronically in supramammary lymph nodes and secretory parenchyma, shedding directly into milk.
• Salmonella Dublin (C): Systemic bacteremia leads to mammary colonization and direct internal excretion.
• Escherichia coli (A): Causes acute coliform mastitis within the glandular lumen.
• Streptococcus uberis / Staphylococcus (D): Established intramammary gland infections shed massive bacterial numbers.
• nalysis:
• All listed bacteria can originate from the interior of the udder. Hence, Option 3 is correct.