Lecture 11: Bacteria and Disease 1 Flashcards
what is virulence?
the pathogenic potential of a microorganism compared to another
what is the microbiome?
collective genomes found within a single microbial ecosystem
what is the microbiota?
community of microorganisms that exist within a single ecosystem
what is a commensal?
a type of microbe that resides on either surface of the body or at mucosa (mucus membrane) without harming human health
what is dysbiosis?
disruption to the normal microbiota linked to many diseases (gut-brain axis, obesity, cancer)
why can bacteria cause obesity?
they don’t use as many calories so human cells do so they become obese
what is a pathogen?
a microorganism that causes disease
what is pathogenesis?
the biochemical mechanisms whereby microorganisms cause disease
what is infection?
successful persistence/multiplication of a pathogen on/within the host
what is disease?
an interaction which causes significant/overt damage to the host
what is a supraorganism?
being part human part microbe
what is gut-brain axis?
when microbes in the gut can give out molecules to the blood affecting the brain’s emotions and wellbeing
what is an opportunistic pathogen?
harmless bacteria that become pathogenic due to changes in the host
what is a facultative pathogen?
a bacteria that can survive outside the host as well as infect them
what is an obligate pathogen?
a pathogen that only survives within the host
what are 3 routes of infection?
anthrax spores, cutaneous, inhalation
what is the virulence factor?
factor produced by the microorganism that enables it to infect the host and cause disease
what are the 4 steps to the INFECTION process?
- exposure
- adherence
- invasion
- multiplication
what is Listeria moocytogenes?
a gram positive bacteria causing gastroenteritis (healthy) or septicaemia/meningitis (immunocompromised)
how do humans become exposed to L.monocytogenes?
unpasteurised dairy products, deli meats and coleslaw
what 2 adherence mechanisms does L.monocytogenes use?
- InlA binds to human E-cadherin found on intestine or placenta
- InlB binds to c-MET allowing colonisation of liver and spleen
how does L.monocytogenes invade the host?
hijacks cell mechanisms by InlA and InlB inducing host cell actin rearrangment and internalisation
how does L.monocytogenes move within the cell to spread?
via ActA since it induces actin polymerisation
how does L.monocytogenes multiply?
- internalisation = vacuole formation
- Listeria Lysin O allows escape to cytoplasm
- bacteria uses nutrients from cytoplasm for replication
