lecture 34 Flashcards
(15 cards)
what are the important types of pathogens?
viruses, fungi, protozoa, helminths, bacteria
what is koch’s postulates?
- guidelines to say that pathogen causes disease
- pathogen must be present in every individual with the disease
- sample of the microorganism taken from the diseased host can be grown in pure culture
- sample of the pure culture causes the same disease when
injected into a healthy host - microorganism can be recovered from the experimentally infected host
what are the exceptions to koch’s postulates?
- microbes that can’t be cultured
- pathogens that are also found in healthy subjects
what are the Key Stages of Microbial Pathogenesis?
- adherence to host cells
- invasion of host cells
- replication within host tissues
- disease causing damage to host tissues
what bacterial virulence factor relates to the adherence to host cells?
fimbrae
what bacterial virulence factors relates to the invasion of host cells?
flagella, Internalin-related proteins
what bacterial virulence factors relates to replication within host cells?
Siderophores (bind iron) and Capsules (resist phagocytosis)
what bacterial virulence factors relates to disease causing damage to host tissues?
toxic virulence factors:
Endotoxins: Cause inflammation Exotoxins: Can be fatal
what are endotoxins?
Lipopolysaccharides (LPS) components found in the outer
membrane of Gram-negative bacteria, and elicit strong immune responses
what are the potential effects of endotoxin?
- fever
- inflammation
- blood clotting
- shock
what are exotoxins?
- proteins produced within living bacteria, and then released into
the surrounding medium - 3 types
- cytotoxins
- neurotoxins
- enterotoxins
what is an example of a function of a cytotoxin?
beta haemolysis (complete red blood cell destruction)
what do cytotoxins do?
cause damage and death to cells
what is a possible effect of neurotoxin?
paralysis
what are enterotoxins?
toxins that affect digestive system, particularly intestines
