Infectious Flashcards
Microbes that can cause disease
Pathogens
Cause disease only in immunocompromised people
Opportunistic pathogens
Measure of a microbe’s ability to cause disease
Virulence
Virulence factors
CapsulesExotoxinsEndotoxins
Number of organisms required to cause disease in 50% of the population
ID50
Presence of microbes in the body and symptoms of disease
Infection
Mechanisms of bacterial disease
Production of toxinsInduction of inflammation
Modes of Transmission: Human to Human
Direct: sexual or transvaginalFecal-oralInhalationTransplacentalBlood-borne
Modes of Transmission: Nonhuman to Human
SoilWaterDirect animal sourceVector-borneAnimal excretaFomites
Surface proteins that mediate binding to endothelium and to extracellular proteins such as fibronectin
Curli
Spread through subcutaneous tissue
Hyaluronidase (destroy connective tissue)Collagenase
Accelerates formation of a fibrin clot coating organisms with a layer of fibrin
Coagulase
Allows adherence to mucous membranes
Immunoglobulin A (IgA) protease
Destroys both neutrophilic leukocytes and macrophages
Leukocidin
Leukocidin of Staphylococcus aureus
Panton Valentine Leukocidin (PV Leukocidin)
Bacteria with IgA protease
Streptococcus pneumoniaHaemophilus influenzaeNeisseria meningitidisNeisseria gonorrhoeae
Protect against phagocytosis; Antiphagocytic factor
Polysaccharide Capsule
Proteins produced to attach to bacteria to be easily engulfed
Opsonins
Anticapsular antibodies allow more effective phagocytosis to occur
Opsonization
Cell protein of S. pyogenes: antiphagocytic
M protein
Cell wall protein of S. aureus that prevents complement activation
Protein A
Source of Exotoxin
Gram (+) and (-)
Source of Endotoxin
Gram (-)
Secreted from cell: Endotoxin or Exotoxin?
Exotoxin
Chemistry of Exotoxin
Polypeptide
Chemistry of Endotoxin
Lipopolysaccharide
Location of genes: Exotoxin
Plasmid or Bacteriophage
Location of genes: Endotoxin
Bacterial chromosome