Mechanisms of Bacterial Pathogenesis Flashcards
nonpathogen
very unlikely to cause disease, very low pathogenicity, very high LD 50
opportunistic pathogen
unlikely to cause disease unless host is debilitated, low virulence, high LD 50
pathogen
routinely causes disease in previously healthy hosts, mid high virulence, low-mid LD 50
virulence factors
genes found experimentally necessary for pathogens to produce disease
involved in surviving extreme environments, adhesion, immune evasion, host cell takeover, poisoning the host
exotoxin
virulence factor secreted from pathogen or injected into host cell by T3SS, profound toxicity may result from superantigenicity, interference with signal transduction, depolymerization of actin, or other activities
often encoded on accessory DNA that comes in on plasmids or by phage infection
toxoid
heat or chemically inactivated exotoxin, often used as vaccine
pathogenicity island
several virulence factors that are regulated together
endotoxin
intrinsic to the surface of bacteria, cause immunogenic symptoms, neither previous exposure nor vaccination is protective
asymptomatic, inapparent, subclinical infection
host defences clear pathogen before any symptoms of disease are noted
noncommunicable infection
comes from environment, not a previous host (botulism, legionnaires disease)
commensals
and normal flora are usually nonpathogens with some opportunistic pathogens (ex. S. aureus on skin)
infectious dose (ID 50)
lower means fewer infecting organisms needed to cause symptoms of disease
lethal dose (LD 50)
lower means fewer infecting organisms needed to kill the host
type 3&4 secretion systems (T3SS)
allows takeover of host cells
actin polymerization
pathways for cell to cell spread
