Veterinary Public Health and Epidemiology- ICAR JRF/SRF 2024

• Pathophysiology of EHEC (Escherichia coli):
• Systemic Complications: EHEC colonizes the large bowel and produces potent Shiga toxins that enter systemic circulation, targeting renal capillary endothelial cells to trigger Hemolytic Uremic Syndrome (HUS) characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure [Statement A is TRUE].
• Shiga-Like Toxins: Produces Stx1 and Stx2 (verotoxins), which inhibit eukaryotic 60S ribosomal protein synthesis [Statement B is TRUE].
• Serotype O157:H7: Prototype EHEC serotype responsible for major foodborne outbreaks [Statement C is TRUE].
• Enzymatic Marker: E. coli O157:H7 is distinctively $\beta$-glucuronidase NEGATIVE and sorbitol non-fermenting on Sorbitol-MacConkey (SMAC) agar, unlike other E. coli which are $\beta$-glucuronidase positive [Statement D is FALSE].

Correct option: (1) (A), (6) and (C) only.

• Poultry Fecal Pathogens:
• Listeria monocytogenes: Readily isolated from poultry droppings and litter, acting as an environmental carrier.
• Campylobacter jejuni: Highly prevalent commensal inhabitant of the poultry gastrointestinal tract (colonizing the cecal crypts at densities up to $10^8\text{ CFU/g}$). Fecal contamination during defeathering and evisceration is the primary contamination route.
• Salmonella Enteritidis: Colonizes the avian intestinal tract and ovarian tissue, leading to vertical transmission in eggs and contamination through fecal droppings.
• Exclusion: Vibrio cholerae is primarily an aquatic bacterium adapted to brackish water environments and human fecal-oral transmission, not poultry faeces.

Correct option: (2) (A), (C) and (D) only.

Evaluating the Assertion and Reason concerning Classifications of food microbes according to their requirements for growth – temperature:

The correct answer is Option 1: Both (A) and (R) are correct and (R) is the correct explanation of (A)..