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Principles of disease (Ross Lilley) > Pathogens and the host > Flashcards

Flashcards in Pathogens and the host Deck (48)
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1

pathogenic bacteria

bacteria capable of causing disease.

2

signs and symptoms of clinical infection

-inflammation
-pain
-pyrexia
-tachycardia
-rigors
-increased white cell count
-increased C reactive protein (CRP)

3

pyrexia

high temp.

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tachycardia

heart rate that exceeds the normal resting rate.

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rigors

sudden feeling of cold, increased temperature, sweating and shivering

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pathogen

organism that can cause disease.

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commensal

organism which is part of the normal body flora.

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requirements for pathogenicity

infectivity
virulence

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infectivity

ability to become established

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virulence

ability to cause harmful effects once established

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methods to increase infectivity

-attachment
-acid resistance

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virulence factors

-invasiveness
-toxin production
-evasion of immune system

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invasiveness example: streptococcus pyogenes

-necrotising fasciitis
-cellulitis
-connective tissue breakdown
-fibrinolysis

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types of toxins produced by pathogens

exotoxins
enterotoxins
endotoxins

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exotoxins

released extracellularly by the micro-organism.

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enterotoxin

act on the GI tract

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endotoxin

structurally part of the gram negative cell wall

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tetanus

caused by clostridium tetani, exotoxin released acts on nerve synapse and causes the inhibition of inhibitory neurotransmitter release.

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tetanus treatment

debridement (removal of dead/infected tissue), antibiotics and antitoxin

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cholera

causes by vibrio cholerae, colonises small intestine produces an enterotoxin which causes increase in cAMP levels, increases ion conc in small intestine which causes dehydration.

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treatment of cholera

rehydration

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superantigens

certain exotoxins of strep pyogenes and Staph aureus stimulate the division of T-cells in the absence of specific antigen. overwhelming cytokine production causes toxic shock

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endotoxin action

caused by E. coli and other gram negative bacilli. induces uncontrolled host response, cytokine production, fevers, rigors hypotension, tachycardia, collapse

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colonisation

the establishment of the pathogen at the appropriate portal of entry

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latent infection

after the primary infection the virus lies dormant in host cells, viral DNA and RNA in host cells which is not expressed in large quantities.

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asymptomatic infection

infected host is a carrier for the disease but does not show any symptoms.

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infection

the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce

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innate immunity

non-specific immunity formed of skin, gastric acid. muco-ciliary escalator and phagocytic cells

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phagocytic cells

-polymorphs eg. neutrophils, eosinophils, basophils (fight acute infection
-macrophages (fight chronic infection)

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aquired immunity

specific response to antigen concerned, an immunological memory is creates.
has a humoral (antibody) and cellular (t-cell) response