III - Infection Biology Flashcards
Microbes that can cause disease
pathogens
Pathogens that cause disease only in the immunocompromised
opportunistic pathogens
Measure of a microbe’s ability to cause disease
virulence
Virulence is determined by
virulence factors - capsule, endotoxin, exotoxin
Number of organisms required to cause disease in 50% of the population
ID50
Presence of microbes, symptoms of disease
infection
Mechanisms of Bacterial Disease
production of toxins, induction of inflammation
Human-Human Bacterial Transmission
sexual, fecal-oral, inhalation, transplacental, blood
Non-Human-Human Bacterial Transmission
soil, water, animal, vector, feces, fomites
Mediates attachment of bacteria
pili
Mediates strong adherence to the surface of human cells
glycocalyx
Surface protein of Salmonella and E. coli that mediate binding to endothelium and to extracellular proteins such as fibronectin
curli
Bacterial Invasion: Spread through subcutaneous tissue
collagenase, hyaluronidase
Bacterial Invasion: Accelerates formation of a fibrin clot coating the organisms with a layer of fibrin
coagulase
Bacterial Invasion: Allows adherence to mucous membranes
IgA protease
Bacterial Invasion: Destroys both neutrophilic leukocytes and macrophages
leukocidin
Bacteria with IgA Protease
Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Neisseria gonorrhoeae
Protects against phagocytosis
polysaccharide capsule
Anticapsular antibodies allow more effective phagocytosis to occur
Opsonization
Antiphagocytic cell wall protein of S. pyogenes
M Protein
Cell wall protein of S. aureus that prevents complement activation
Protein A
Exotoxin: Source
gram (+), gram (-)
Exotoxin: Secreted from cell?
yes