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Flashcards in Host parasite relationships Deck (17):

What is the causative agent of strep throat?

Streptococcus pyogens (Group A strep)


What are opportunistic pathogens?

1. Tend to be members of normal microbiota2. Take advantage of preexisting conditions, such as immunosuppression to grow and cause disease


What is pathogenicity?

Ability of a microorganism to cause disease


What is virulence?

Measurement of pathogenicity


What is a carrier?

1. Asymptomatic individual who is host to a pathogen 2. Has the potential to transmit pathogen to others3. Condition of being a carrier may be transient or (semi) permanent


What are the events associated with infection?

1. Entry into host2. Adhesion, colonization, pathogenic action 3. Escaping host defense


How is adhesion obtained?

1. Adhesins, or attachment proteins, are often but not always associated with bacterial pili2. Specific adhesin and receptor combinations often define tropism


What are biofilms?

1. Bacteria encased in an exopolymeric substance of their own making2. Altered metabolism, usually slower3. Increased antibiotic resistance4. Increased genetic exchange5. Resistance to disinfection (decreased diffusion, increased organic matter)


What characterizes pathogenic action of bacteria?

1. Invasion into cells (hijack host cell machinery, modulate maturation of phagosome to promote survival)2. Dissemination (can cause disease at location far from initial infection site)


What are exotoxins?

1. Bacterial products that directly harm tissues or lead to destructive biologic activites2. Cytolytic enzymes3. Receptor binding proteins that initiate toxic reactions)4. A = active5. B = binding


What are superantigens?

1. Bind both TCRs and MHC 2 without requiring an antigen2. Activation of large amount of cytokines with life threatening autoimmune type response


What are characteristics of encapsulation?

1. Generally a poor antigen2. Masks more antigenic epitopes on bacterial surface3. Prevent binding of antibody or complement


What are characteristics of antigenic mimicry?

Bacteria can produce compounds the host sees as self


What are characteristics of antigenic shift?

1. Quickly change antigenic makeup of proteins on cell surface2. Moving target


What are characteristics of inactivation antibody?

Secretion of proteases that degrade specific antibody isotypes


What are characteristics of resistance to complement mediated killing?

1. Limited access to membrane2. Degradation of complement components


How are virulence factors regulated?

1. Quorum sensing2. Regulation of gene expression in response to population size3. A way for bacteria to act as a multicellular group of organisms as opposed to individuals carrying out a genetic program