Lecture 67 - Microbial pathogenesis Flashcards
define commensal
colonizer, normal, benign
define pathogen
causes disease, either opportunistic or obligate
define pathogenicity
relative ability of a pathogen to cause disease
define virulence factors
molecules that increase efficiency of infection of disease severity
what are the 5 virulence factor actions? give examples.
- colonize (adhesins)
- invade (invasins)
- evade barriers and defense (enzymes)
- suppress immune response (enzymes)
- acquire nutrition (siderophores)
what are the portals of entry
- ingestion
- inhalation
- ascending
- direct contact/cutaneous penetration
what are the alimentary system defenses
- mucus secreted by goblet cells
- acidic pH environment
- MALT/GALT/Peyer’s patches
- microfold (M) cells
- IgA
what are respiratory system defenses
- mucociliary clearance
- surfactants
- BALT
- IgA
- alveolar macrophages
what are skin defenses
- thick physical barrier
- dryness + acidity
- cool temperature
- sebum
- Largerhaan cells
which is an important component of microbial defense in the skin
dry, acidic environment
what are the 4 steps of bacterial pathogenesis
- adhesion
- colonization
- invasiveness
- toxigenesis
what are 3 adherence factors
- adhesins
- pili
- fimbriae
what releases iron from intracellular stores for bacterial utilization
siderophores
what is lipopolysaccharide
- endotoxin
- stimulates host immune response
- can stimulate excessive levels of cytokines
what are exotoxins
- enzymes
- toxins altering intracellular/regulatory pathways
- neurotoxins or superantigens
describe clostridium botulinum
- disruption at the neuromuscular junction
- cleaves SNARE proteins (accumulation of AcH)
- flaccid paralysis
describe Clostridium tetani
- neural-neural junction
- inhibition of glycine release
- spastic paralysis
pathogenicity islands
virulence genes present in clusters on bacterial chromosome
what are the 3 routes of horizontal gene transfer
- transformation
- transduction
- conjugation
what are the toxins produced by Bacillus anthracis
- edema factor
- protective antigen
- lethal factor
what is associated with toxins produced by Clostridium tetani
inhibition of GABA and glycine at the neural-neural junction
tropism depends on
presence of viral receptors on host cells
what are the 5 outcomes of viral replication
- lysis
- apoptosis
- persistence/latency
- proliferation
- malignant transformation
what are viral virulence factors
- evasion
- caspases
- viral toxins
antigenic drift
natural and spontaneous mutations
antigenic shift
formation of a new virus with mixed genes
which is a characteristic of some viral infections
formation of syncytial cells
fungal virulence factors
- cell wall
- capsules
- glucans/glycoproteins
- antioxidants
- toxins
describe the 4 steps in fungal pathogenesis
- cell wall/capsule and other virulence factors
- protection of microbe against defense mechanisms
- fungus not removed/degraded
- chronic inflammation
describe prions
transmissible protein aggregates lacking an infectious genome
what is converted in prion disease
normal cellular prion protein to the abnormal form
T/F: prions cause gross lesions
FALSE
