Infectious Diseases Transmission and Virulence PDF

Infectious Diseases Transmission and Virulence Mechanisms Encounter Adherence Evasion of Immune System Multiplication and Spread Cell/Tissue Damage Shedding Source Exogenous Endogenous-commensalism or mutualism Skin-Staph Intestines-gram negatives, anaerobes, fungi Nas...

Infectious Diseases Transmission and Virulence Mechanisms Encounter Adherence Evasion of Immune System Multiplication and Spread Cell/Tissue Damage Shedding Source Exogenous Endogenous-commensalism or mutualism Skin-Staph Intestines-gram negatives, anaerobes, fungi Nasal/Oropharynx-Staph, Strep, anaerobes Exogenous Fomites Listeria, E.coli, Salmonella Animal and insect vectors Many viruses, malaria, encephalitis, typhus, leptospirosis, tularemia, parasites Other humans Strep pneumoniae, viruses, STDs, tuberculosis Air borne, body fluids Transmission Most organisms have a defined survival outside of hosts except some fungi and bacteria (anthrax) which can form spores Adherence Virtually all viruses adhere and enter cells by specific receptors or proteins that the viral capsid adheres to- examples include Covid-19 (angiotensin II converting enzyme receptor) and HIV (CD4 cell antigen) Gram + bacteria adhere to cell surface through peptidoglycans in bacterial cell wall Gram – bacteria adhere through antigens on flagella, pili, or fimbriae HIV Q and A Spread/Multiplication Production of toxins E. coli, Clostridium difficle, Super antigens-Staph Secretion of enzymes Streptolysin, proteases. Lipoprotein saccharide Toxin Production Gram negative organisms-Endotoxin, LPS of cell wall Fever, Permeability changes Vasodilation-septic shock A-B toxins Clostridium tetani Synaptic transmission Vibrio cholera ADP ribosylation Evading Host Immune Response Inhibition of chemotaxis C5a-Strep Killing of phagocyte Α-toxin-Staph Avoiding ingestion LPS, κ-capsule of Strep Avoiding complement lysis Coating with IgA antibodies-Nisseria Surviving within the phagocyte Inhibition of endosome-lysozyme fusion=Chlamydia Inhibition of NADPH oxidase-Salmonella Inhibition of H+-ATPase-tuberculosis Survival within Host Phagocyte Inhibition of Endosome-lysosome fusion-Chlamydia Inhibition of NADPH Oxidase-Salmonella Inhibition of endosomal H+-ATPase-tuberculosis Antibiotic Resistance Induction or modification of enzymes that inactivate drugs-penicillinase cleaves β-lactam ring structure Multidrug Resistant Transporter Alteration of Metabolic Function Phage Transfer