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DISTINCTIVE PROPERTI16 - that inactivates IgA • Toxigenic...

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DISTINCTIVE PROPERTIES: Corynebacterial cell walls contain thin spots which leads to some Gram variability and "ballooning" that produces a "club-shaped" cell. Old cells store inorganic phosphate, which can appear as metachromatic granules when stained. PATHOGENESIS: C. diphtheriae is the etiologic agent of diphtheria. These organisms colonize the mucus membranes of the respiratory tract and produce the enzyme neuraminidase which splits N-acetylneuraminic acid (NAN) from cell surfaces to produce pyruvate which acts as a growth stimulant. C. diphtheriae also produces diphthin, which is a protease
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Unformatted text preview: that inactivates IgA. • Toxigenic strains carry the gene tox , which resides on certain bacteriophages; lysogenization leads to toxigenicity. • The toxin that is produced is a single polypeptide of 62,000 daltons and contains a single disulfide cross-link. Digestion with trypsin gives 2 fragments, A and B. The B (binding) fragment attaches to cell surfaces then proteases release the A (active) fragment to enter the cell. In the cell, the toxin acts as an ADP-ribosyltransferase, inactivating translation factor EF2....
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