Lecture 9 - Corynebacterium-Rhodococcus Nocardia

Lecture 9 - Corynebacterium-Rhodococcus Nocardia -...

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Unformatted text preview: Overview: Gram-Pos Rods Gram+ Rod Spores- + Shape regular irregular Acid Fast- + Branched Filaments- + Clostridium Nocardia Coryne- Bacterium/ Rhodococcus Myco- bacterium Listeria CMN-Group CMN group CMN group relationship C orynebacterium M ycobacterium N ocardia All express unusual cell wall components:-mycolic acid- Cord Factor General Characteristics Cell wall structure Cell Wall:Figure 29-1 Mycobacterial cell wall structure. The components include the (A) plasma membrane, (B) peptidoglycans, (C) arabinogalactan, (D) mannose-capped lipoarabinomannan, (E) plasma-associated and cell wall-associated proteins, (F) mycolic acids, and (G) glycolipid surface molecules associated with the mycolic acids. Mycolic Acid and Cord Factor Arabino- galactan Mycolic acids Mycolic acids Mycobacteria Mycobacteria longest chain length longest chain length strongly acid fast strongly acid fast Nocardia/Rhodococcus Nocardia/Rhodococcus intermediate chain length intermediate chain length weakly acid fast weakly acid fast Corynebacteria Corynebacteria shortest chain length shortest chain length not acid fast not acid fast Lecture 10 Corynebacterium Nocardia, Rhodococcus Classification Genera Species Corynebacterium C. diphtheriae C. jeikeium C. pseudotuberculosis C. pseudodiphtheriticum C. urealyticum C. ulcerans Pathogen Opportunistic Pathogens-can be part of common microflora Microscopic Morphology Gram positive pleiomorphic rods- grouped together in V or Chinese letter shape No spores Metachromatic granules (Methylene blue staining) Not Acid-fast Physiology Aerobic; facultatively anaerobic Enhanced by CO 2 Catalase positive Grows as a waxy pellicle on the surface of liquid media Carbohydrate fermenting to lactic acid Pathogenic Factors Cord factor (trehalose dimycolate=dimer of mycolic acid) Exotoxin result of phage conversion!! Beta-phage C. diphtheriae Exotoxin (general) Type III (intracellular) toxins 1. A-B Toxins: two chain molecules B-subunit mediates binding to target cell and internalization A-subunit inhibits intracellular target Toxin targets very well defined tissues/cells ( V.cholerae, B.anthracis, C.tetani ) Toxin action Inhibits elongation factor 2 Pathogenic Factors Exotoxin (contd) Two component toxin A & B Fraction A 21,500 kDa Fraction B 40,000 kDa Pathogenic Factors...
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This note was uploaded on 01/24/2011 for the course BSCI 424 taught by Professor Staff during the Fall '08 term at Maryland.

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Lecture 9 - Corynebacterium-Rhodococcus Nocardia -...

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