An outbreak of abdominal tuberculosis occurs among villagers who consume raw milk from infected cattle. Culture of mesenteric node biopsy yields acid-fast bacilli. A notable feature of this organism's drug susceptibility profile is:

• A Natural resistance to rifampicin
• B Natural resistance to pyrazinamide ✓
• C Natural resistance to isoniazid
• D Universal susceptibility to all first-line drugs

Explanation

The organism is Mycobacterium bovis, acquired through unpasteurized milk and a recognized cause of intestinal tuberculosis and scrofula. M. bovis is inherently resistant to pyrazinamide because it lacks functional pyrazinamidase activity, so standard short-course regimens must be modified. It remains susceptible to isoniazid and rifampicin unless acquired resistance develops. This intrinsic PZA resistance is the single most examined distinction between M. bovis and M. tuberculosis.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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