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BACTERIAL PATHOGENESIS

BACTERIAL PATHOGENESIS. Initiation of infectious process & mech that lead to the development of S & S of disease ADHERENCE – INFECTION –multiplication of an infectious agent in the body INVASION –process by which bacteria enter & spread in the body

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BACTERIAL PATHOGENESIS

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  1. BACTERIAL PATHOGENESIS • Initiation of infectious process & mech that lead to the development of S & S of disease • ADHERENCE – • INFECTION –multiplication of an infectious agent in the body • INVASION –process by which bacteria enter & spread in the body • PATHOGEN –a microorg capable of causing disease

  2. BACTERIAL PATHOGENESIS • OPPORTUNISTIC PATHOGEN –A microorg capable of causing disease only when host,s resistance is impaired • PATHOGENICITY –the ability of an infectious agent to cause disease • TOXIGENICITY –the ability of an microorg to produce a toxin that contribute to development of disease • VIRULENCE –the quantitative ability of an agent to cause disease

  3. BACT PATHOGENESIS -STAGES • 1 -entery in to host with evasion of host primary defenses • 2 -adhesion of microorg to host cells • 3 -propagation of org • 4 - damage to host cells by toxins or inflammatory response • Evasion of host secondary defenses

  4. BACT PATH -DETERMINANTS • TRASMISSION – • ROUTES – inhalation, ingestion, inoculation

  5. BACT PATH –PORTAL OF ENTERY • RESP TRACT –S. pneumonia, N. meningitidis, H. influenzae, M. tuberculosis, influenza virus, • GIT –Shigella spp, Salmonella spp, V. cholerae, HAV, HEV, poliovirus • SKIN –C. tetani, Rabies virus, plasmodium spp, • GENITAL TRACT –N. gonorrhoeae, T. pallidum, C. trachomatis, Candida albicans, HSV,

  6. MODES OF TRANSMISSION • HUMAN TO HUMAN – • Direct contact –gonorrhea • No direct contact- dysentery • Nonhuman to human – • Soil –tetanus • Water –legionnaire,s disease • Animal source- • Directly –cat scratch disease • Via insect vector –Lyme disease

  7. BACT PATHOGENESIS • ADHERENCE TO HOST CELLS – • Fimbrial (Pili) –N. gonorrhea, E. coli • Afimbrial –cell surface adhesion molecule -Glycocalyx – Staph epidermidis, S.viridans- endothlium of heart valves • Extracellular polysccharides of Streptococcus mutans ( enamel surface)

  8. BACT PATHOGENESIS • INVASION- depend on bacterial enzymes • Collagenase & hyaluronidase ( cellulitis by S. pyogenes) • Coagulase –S. aureus • Ig A protease –N. gonorrhea, H. influenza. S. pneumonia • Leukocidins

  9. BACT PATHOGENESIS • Antiphagocytic factors – • Capsule –S. pneumonia, N. meningitidis, • Cell wall protein of Gram +ve cocci • M protein of S. pyogenes • Protein A of S. aureus • Invasion is followed by inflammation –pyogenic or granulomatous depending on org

  10. BACT PATH

  11. MODE OF ACTION ENDOTOXIN IL-1(fever) TNF(fever,hypotension NO(hypotension)

  12. Effects of IL -1 • In vivo –hypotension, fever, edema, leukocytosis, wasting, • In vitro –direct cytotoxicity, cell-mediated cytotoxicity, vascular adhesion, • Effects of IL –2 – • Hypotension, fever, edema,

  13. BACT EXOTOXINS

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