MCPHS Microbiology Exam Study Guide with Complete Solutions

MCPHS Microbiology Exam Study Guide with Complete Solutions Pathogenicity - Answer️️ -The ability to cause disease Virulence - Answer️️ -the extent of pathogenicity Portals of entry - Answer️️ -mucous membranes, skin, parenteral route ID50 (infectious dose) - Answer️️ -The number of microbes that must enter the body to establish infection in 50% of test animals is expressed as the ID50 LD50 - Answer️️ -lethal dose (of a toxin) for 50% of the test population Adherence - Answer️️ -Adhesions / ligands bind to receptors on host cells, form biofims Glycocalyx: streptococcus mutans Fimbriae: E.coli M proteins: Strepoccus pyogenes Pili, flagella, glycoproteins, lipoproteins Capsules - resist phagocytosis - Answer️️ -Strep. Pneumoniae, Hib, bacillus anthracis cell wall components - Answer️️ -M proteins: mediates attachment and resists phagocytosis (strep. pyogenes) Opa protein: assist attachment and recept mediated endocytosis, inhibs helper t cells (n. gonorrhoeae) Mycolic acid: Waxy, resists digestion (mycobacterium TB) ©SOPHIABENNETT EXAM SOLUTIONS_2024/2025 Monday, September 2, 2024 12:59 PM Page | 2 Enzymes - Answer️️ -Coagulase: coagulates fibrinogen Kinases: digest fibrin clots hyaluronidase: hydrolyzes hyaluronic acid Collagenase: hydrolyzes collagen IgA proteases: destroys IgA antibodies antigenic variation - Answer️️ -Alteration of surface antigens to avoid detection by host antibodies Examples: flu, gonorrhea, trypanosoma brucei gambiense Invasins: Penetration into the host cell cytoskeleton - Answer️️ -Salmonella alters host actin to enter a host cell Listeria uses actin to move from one cell to the next Direct damage caused by - Answer️️ -disrupting the host cells function produces waste products toxins induce hypersensitive reactions damage immediate vicinity use hosts nutrients (iron) -siderophores Siderophores - Answer️️ -proteins that free host stores of iron Toxin - Answer️️ -substance that contributes to pathogenicity Toxoid - Answer️️ -inactivated toxin used in a vaccine Antitoxin - Answer️️ -antibodies against a specific toxin ©SOPHIABENNETT EXAM SOLUTIONS_2024/2025 Monday, September 2, 2024 12:59 PM Page | 3 Endotoxins - Answer️️ -the lipid portions of lipopolysaccharides (LPS) that are part of the outer membrane of the cell wall of gram-negative bacteria. The endotoxins are liberated when the bacteria die and the cell wall breaks apart. PART OF BACTERIAL CELL NOT A PRODUCT Lipid NOT proteins all produce same SS Exotoxins - Answer️️ -specific for a structure or function in ho