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Bacterial Immunity

Bacterial Immunity. EXTRACELLULAR BACTERIA. Extracellular bacteria are mostly pathogenic residing in the blood, connective tissues, tissue spaces such as the lumens of the airways and gastrointestinal tract disease is caused by two principal mechanisms inflammation Toxins

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Bacterial Immunity

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  1. Bacterial Immunity

  2. EXTRACELLULAR BACTERIA • Extracellular bacteria are mostly pathogenic residing in • the blood, • connective tissues, • tissue spaces such as the lumens of the airways and gastrointestinal tract • disease is caused by two principal mechanisms • inflammation • Toxins • Endotoxins: activate phagocytes and APCs • Exotoxins: cause damage by cytotoxicityor by interfering with normal physiological cell functions

  3. Innate Immunity to Extracellular Bacteria • The principal mechanisms of innate immunity to extracellular bacteria are • complement activation enhances opsonizationand phagocytosisof the bacteria • Peptidoglycan and LPS activates the alternative pathway of complement in the absence of antibody • Activation of phagocytes and inflammation • Phagocytes use various surface receptors (mannose and scavenger receptors) to recognize extracellular bacteria, • and they use Fc receptors and complement receptors to recognize bacteria opsonized with antibodies and complement proteins, respectively

  4. Some receptors • promote the phagocytosis of the microbes (e.g., mannose receptors, scavenger receptors) • others recognize PAMPs and stimulate the microbicidal activities of the phagocytes (mainly TLRs) • promote both phagocytosis and activation of the phagocytes (Fc and complement receptors)

  5. Erysipelas (red skin; also known as "Ignissacer", "holy fire", and "St. Anthony's fire“is an acute streptococcusbacterial infection[2] of the upper dermis and superficial lymphatics. Cellulitis is a localized or diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Impetigo

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