Lecture 17 - Microbial infection and pathogenesis Flashcards
what is microbial adherence?
enhanced ability of the microbe to attach to the host tissues, not sufficient to start disease
how do pathogens typically adhere to epithelial cells?
through interactions between molecules on the pathogen and host tissues, can also form biofilm and adhere to the host through them
what are adhesins and what are they made up of?
receptors on pathogens surface to enable it to bind to host cell, made up of glycoprotein or lipoprotein
what do host cell receptors include?
extracellular matrix, cell surface glycoproteins and membrane lipids
where does the bacterial capsule form?
around the plasma membrane and cell walls
what two important functions does the bacterial capsule serve in bacterial
pathogenicity
- its sticky and contains specific receptors that facilitate attachement to host tissues
- they can evade the host defense system
what is colonization?
the growth of microorganisms once they have gained entrance to the host tissue, usually starts in mucous membranes
what is dental plaque?
thick biofilm caused by extensive microbial growth
what is invasion?
the ability of a pathogen to grow in host tissue, spread, and cause disease
what is bacteremia?
the presence of bacteria in the bloodstream; usually asymptomatic because immune system will remove them
what is septicemia?
bacteria multiplying in the bloodstream and spreading systematically from an initial point; produce toxins
what is virulence?
ability of a pathogen to cause disease
what are virulent factors?
toxic or destructive compounds produced by the pathogen to directly or indirectly enhance invasiveness and host damage by facilitating and promoting infection
what is virulence attenuation?
the decrease or loss of virulence
what is the outcome of an infectious disease?
net result of physiological and genetic features of pathogen and host
what are pathogenicity islands?
cluster of genes associated with pathogenicity on the chromosome
what are oppurtunistic infections?
caused by organisms that do not cause disease in healthy hosts
what are compromised hosts?
individuals in whom one or more mechanisms of disease is inactive
what are nosocomial infections?
healthcare associated infections
what does coagulase do?
promotes blood clotting, blocking access to the bacteria by the immune system
what does streptokinase do?
dissolves blood clot formed by the host to isolate the pathogen
what are exotoxins?
toxic proteins secreted by the pathogen
what are enterotoxins?
exotoxins whos site of action is the small intestine, causing secretion of fluids into intestinal lumen, resulting in vomitting and diarrhea
what are the three classes of exotoxins?
- AB toxins
- cytolytic toxins
- superantigen toxins
