Pathogen-host interactions and microbiota Flashcards
What are the types of interactions?
Symbiosis (one +), communalism (one +, one=), mutualism (2 +), parasitism (one +, one -)
What is a true pathogen?
Causes disease in healthy individuals
What is an opportunistic pathogen?
Wrong place or wrong patient
Explain the “via molecules” mechanism of interaction
Decorating surface of bacterial cell OR
Secreted into growth medium (toxins) or host cytoplasm (protein secretion)
What are pathogenicity factors?
Properties that enable bacterium to establish itself on/within host and enhance potential to cause disease
Example of pathogenicity factors
Toxins
Cell surface proteins mediating attachment
Capsule
Secreted hydrolytic enzymes
Example of microbial adaptions for infection
Pili/fimbriae
Virulence plasmids
Toxins (haemolysin)
LPS (g. neg have LPS on OM)
Pathogenicity island
What are exotoxins?
Toxins that damage host cell tissue
EX: pore forming toxins (haemolysins)
What are haemolysins?
Membrane-damaging toxins that form pores
Ability of lyse RBC on blood agar plates
What do adhesins do?
Stick to cells and affect host cells
What are adhesins?
Sticky ligands mediating adherence or binding of microbes to receptors on host cell surface
What are fimbriae?
Thin, protein tubes
Most in gram. neg
What do fimbriae do?
Adhere to receptors on target host cells
Bind without contact and electrostatic repulsion
Involved in plasmid transfer
Examples of non-fimbrial adhesins
Bacterial cell-surface proteins
Exopolysaccharides
Lipopolysaccharides (g.-)
Teichoic acids (g.+)
Flagella
What are receptors?
Host molecules/ligands that microbial adhesins bind to, to initiate adherence
