Infection And Immunity Flashcards by Elizabeth Stevens

Why do individuals get particular infections?

Weakened immune system
Genetic predisposition
Poor living conditions
Poor nutrition
No access to healthcare - vaccinations
Lifestyle

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Gram staining process

positively charged crystal violet binds to negatively charged cell components
iodine forms a complex with the crystal violet
methanol/acetone extract complexes through Gram negative cell walls only
red dye stains the unstinted Gram negative cells

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What influences the outcome of an infection?

Immune system
Drugs used
Body systems affected

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What is an infection?

Multiplication/colonisation of pathogens in a susceptible host causing damage/dysfunction

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Which bacteria do acid fast stains detect?

Mycobacterium - cause TB and leprosy

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What is a non-pathogen?

A bacterium that doesn’t cause disease

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Lists some DNA enveloped viruses

Hep B
Smallpox
Herpes

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Non- enveloped DNA viruses

HPV

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RNA enveloped viruses

HIV
Rubella
Rotavirus
Coronavirus

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RNA non-enveloped viruses

Picomaviruses - hep A, polio, colds

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Give some Gram negative bacteria

Neisseria
Escherichia
Salmonella
Helicobacteria
Pseudomonas
Legionella
Bacteroides

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Gram positive bacteria

Staphylococcus
Streptococcus
Clostridium

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What size are the ribosomes of prokaryotes?

30 + 50S

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Which group does vancomycin belong to and what does this target?

Glycopeptide - cell wall

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Which three antibiotic groups target protein synthesis in bacteria?

Aminoglycoside
Macrolide
Polyketide

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Which antibiotic belongs to the chemotherapeutic group and what does it target?

Ciprofloxacin

DNA

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What does reservoir mean?

Any person, animal, plant, soil or substance in which an infectious agent multiplies

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What is a source

A readily available form of an infectious agent

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What does carriage mean?

The route taken by a pathogen eg nasal

What does commensal mean?

The symbiotic relationship where one species benefits and the other is unaffected. Time when the microbe is replicating or waiting for the immune system to be compromised.

How does rifampicin work?

Binds to bacterial RNA polymerase preventing transcription.

How does tetracycline work?

Targets bacterial protein synthesis by competing with tRNA at A site of bacterial ribosome.

What is methotrexate and how does it work?

An anti-folate in cancer therapy.
Impairs the synthesis of tetrahydrofolate which is essential for DNA synthesis from folic acid.
Competitively inhibits dihydrofolate reductase (DHFR)

List 5 ways that cells can become resistant to antibiotics

High rate of division
Decreased influx
Increased efflux
Increased transcription of target
Altered target

Give features of the innate immune system

The inbuilt immunity to resist infection Present from birth Not specific for any particular microbial substance Not enhanced by second exposure Has no memory Uses cellular and humoral components Poorly effective without adaptive immunity

Give features of adaptive immunity

``` Immunity established to adapt to infection Learnt by experience Pathogen-specific immunity Enhanced by second exposure Has memory Uses cellular and humoral components Poorly effective without innate immunity ```

List the cells involved in innate immunity

``` Macrophages and monocytes Neutrophils Eosinophils Basophils Mast cells Natural killer cells ```

What are phagocytes?

Cells able to engulf and destroy bacteria, extracellular fibres and immune complexes

What is opsonisation?

The covering of a microorganism by antibodies or complement to render it recognisable as foreign by phagocytes, thus enhancing phagocytosis

What does the complement system do?

Marks pathogens for their destruction by covalently binding to their surface

What are the cells of the adaptive immune response?

T and B cells

What do macrophages do?

Phagocytosis | Present antigens to lymphocytes (adaptive immunity)

What do transferrin and lactoferrin do? In at or adaptive?

Deprive pathogens of iron | Innate

What do interferons do? Innate or adaptive?

Inhibit viral replication | Innate

What does lysozyme do? I or A?

Breaks down peptidoglycan in bacterial cell walls | Innate

What does fibronectin do? I or A?

Opsonises bacteria and promotes their phagocytosis

What does TNF-alpha do?

Suppresses viral replication and activates phagocytes

What role do neutrophils play? I or A?

Phagocytic and antibacterial | Innate

What do eosinophils do? I or A?

Anti-parasite and allergic response | Innate

What do basophils and mast cells do? I or A?

Allergic response | Innate

What do natural killer cells do? I or A?

Recognise and kill abnormal cells eg tumours | Innate

What do cytokines do? I or A

Promote the differentiation and proliferation of lymphocytes | Adaptive

What does penforin do? I or A?

Released by T killer cells and destroys cell walls | Adaptive

What do antibodies do? I or A?

Protects the host by - neutralisation (prevents binding to epithelia) - opsonisation - complement activation (enhances opsonisation and lysis) Adaptive

T helper cells? I or A?

Become activated when CD4 binds to a specific antigen on the MHC/antigen complex of an antigen presenting cell (APC). Once activated, it clones itself to form T helper an T memory cells Adaptive

B cells?

Divide to form plasma cells and memory cells when activated by T helper cells and release cytokines Plasma cells produce specific immunoglobulin for non-self antigen