L2 - The mico-organism Flashcards Preview

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Flashcards in L2 - The mico-organism Deck (8)
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Define a microbial pathogen

A microbial pathogen is an agent capable of causing disease in a host


What is the difference between infection and disease?

A disease is a disorder of structure or function producing signs/symptoms in a host An infection can incontrast, be asymptomatic


What are commensals?

Commensals are colonies of bacteria (generally) that exist on the human body, deriving benefit from the host, but usually doing it no harm. Heavily colonised areas include the oral cavity, the bowel, the vagina and the skin


What is a sterile body site and where are some of these sites?

An area where there should be no commensal bacteria. Includes the blood, the joint sites and the bladder


What is carriage?

When pathogenic organisms are found amongst commensal bacteria but are causing no disease or infection. Includes Staphylococcus aureus, often carried in the nose and skin, and Streptococcus pneumoniae. Carriage may be exogenous (picked up) or endogenous (continued carriage after illness)


Give an example of an opportunistic fungal yeast

Candida albicans. Mild skin disease but can cause life-threatening systemic disease if able to bypass immune response and get into the blood


What are virulence factors? Give an example

Virulence factors are microbial factors which enable the microorganism to cause disease in a susceptible host.
Example: cholera toxin released by Vibrio cholerae, which disrupts membrane transport mechanisms, causing violent diarrhoea


What are the stages of microorganism invasion?

Survive env.
Transmission to host
Adhere to tissues
Begin colonisation
Invade host
Spread in host
Survive in host
Start disease mechanisms

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