Which statement about Treponema pallidum subspecies pallidum is correct?

• A It possesses abundant outer membrane proteins that provoke strong early inflammation
• B It contains lipopolysaccharide in its outer membrane accounting for systemic toxicity
• C It is readily cultured on chocolate agar enriched with rabbit serum
• D It cannot be cultivated continuously in vitro on artificial media and has a paucity of outer membrane proteins ✓

Explanation

T. pallidum is an obligate human pathogen that cannot be grown continuously in vitro on artificial media; propagation requires rabbit testicular inoculation or tissue culture systems. Its outer membrane contains very few integral proteins (the 'stealth' adaptation) and lacks lipopolysaccharide entirely, which explains why untreated syphilis evolves slowly with little acute toxicity. Its motile corkscrew morphology and periplasmic flagella are characteristic, but the absence of LPS and sparse exposed antigens are the features that distinguish it from typical gram-negative pathogens.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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