Microbiology Flashcards

1
Q

What is meant by nosocomial infection and when can it be diagnosed?

A

An infection due to an organism which was acquired at hospital - can be diagnosed after 48 hours after admission to hospital

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2
Q

Name 4 important bacterial causes of nosocomial infection and state whether they are gram positive or negative. (4+4)

A

Enterococcus Faecium – G+ve
Staphylococcus Aureus – G+ve
Clostridium Difficile – G+ve
Acinetobacter Baumanii – G-ve

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3
Q

Some patient has a lung infection. List three ways to collect a sample from them

A

Bronchoalveolar lavage
Nasopharyngeal aspirtate
Lung biopsy
Sputum

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4
Q

List four bacteria that can be cultured from them (sample lung infection)

A

Mycobacterium
Streptococcus pneumonia
Haemophilus influenza
Klebsiella pneumoniae

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5
Q

Explain why looking at sputum and doing a tissue stain is useful

A

Sputum – easy to obtain and can test many diseases as the pathogens would be trapped in it
Tissue stain – Determines if gram negative or positive: so identifies appropriate treatment

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6
Q

Give an example of a gram positive infection, say what antibiotic it is resistant to and say how the antibiotic works

A

Staphylococcus Aureus – resistant to methicillin

Methicillin – works by inhibiting activity of penicillin binding proteins that inhibit peptidoglycan synthesis

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7
Q

Give examples of bacterial pathogens that can be vaccinated for

A
Haemophilus influenza
Neisseria Meningitides
Streptococcus pneumonia 
Clostridium diphtheria
Bordetella pertussis
Clostridium Tetani
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8
Q

Give examples of bacteria causing respiratory tract infections

A
Legionella pneumophilia (Gram -ve)
Mycobacterium tuberculosis (mycobacterium)
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9
Q

Give examples of bacteria causing STIs

A
Chlamydia trachomatis (obligate intracellular)
Neisseria gonorrhoeae (Gram -ve)
Treponema pallidum (causes Syphilis)
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10
Q

Give examples of viruses causing STIs

A

HepB virus
HepC virus
HIV/AIDS

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11
Q

List some food- and waterborne diseases and zoonoses

A

Campylobacterosis (?)
Cholera (Vibrio cholera)
Listeriosis (Listeria monocytogenes)
Shigellosis (Shigella spp.)

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12
Q

Define an outbreak

A

When a greater number of individuals than what is normal or expected become infected or diagnosed with a particular infection in a given period of time or particular place or both

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13
Q

How are outbreaks measured, and why is it important?

A

Identified by surveillance with an established and timely reporting system
Important to identify early, quarantine to prevent further transmission, identify organism and treat

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14
Q

Name 4 types of protozoa and examples of each (4)

A

Amoeba – Entamoeba histolytic
Coccidia – Toxoplasma; Plasmodium spp.
Ciliates – Balantidium Coli
Flagellates - Trichromonas

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15
Q

What is the difference between protozoa and metazoan?

A

Protozoa are single celled organisms which do not cause eosinophilia while metazoa are multi-celled organisms which do cause eosinophilia

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16
Q

What are the two types of leishmaniasis and give features of each

A

Promastigote – in sand-fly vector. Can move in direction of their flagellum and can be cultured
Amastigote – In humans and other vertebrate hosts. No longer motile. Intracellular form of the parasite

17
Q

What cell type do leishmania reside in?

A

Macrophage

18
Q

What are endotoxins and exotoxins

A

Exotoxins – Toxins that are produced by bacteria and released extracellularly, e.g. neurotoxins and enterotoxins
Endotoxins – Lipid A moiety of lipoproteins produced by Gram negative bacteria which are shed in steady amounts from living bacteria

19
Q

What are Pyrogenic toxins

A

Exotoxins which stimulate cytokine release and thus cause fever

20
Q

Name the general term for the type of toxin that binds directly to both MHCII and T cell receptors.

A

Superantigens

21
Q

Name some virulence factors other than toxins that are used by bacteria

A
Diverse secretion system – e.g. camplylobacter
Flagella – e.g. camplylobacter
Pilli – e.g Neisseria 
Capsule- e.g. streptococcus pneumonia 
Endospores – e.g. clostridium species
Biofilms – e.g. pseudomonas aeruginosa
22
Q

Name two examples of flagellates and the diseases they cause

A

Giardia Lamblia – Diarrhoea, greasy stools, stomach or abdominal cramps, nausea and vomiting and dehydration
Trichromonas – discharge and dysuria

23
Q

Name two examples of coccidiae and the diseases they cause

A

Toxoplasma gondii – can cause toxoplasmosis

Cryptosporidium – diarrhoea, fever, nausea and vomitting

24
Q

Name the 3 helminth infections

A

Ascariasis (Ascaris roundworms)
Schistosomiasis (flukes - Schistosoma)
Taenia = Flatworms => taeniasis

25
Two types of viruses with genetic drift and we have vaccines for them.
Influenza is one with genetic drift and vaccines available
26
Explain Genetic drift vs Genetic shift.
Antigenic drift = Continued rapid evolution driven by antigenic pressure from the host Antigenic shift = Introduction of a new subtype from an animal source therefore existing as a different genetically stable serotype that co-circulates in humans
27
Talk about how viruses evade interferon detection
Hide PAMPS Interfere globally with host cell gene expression and/or protein synthesis Block interferon signalling cascade by destroying or binding to cascade components Inhibit interferon signalling Block activation of individual interferon induced antiviral enzymes Activate SOCS suppression of interferon 1 induction Have a replication strategy which is insensitive to interferon signalling
28
Give two examples of cytoplasmic sensors for viruses
cGAS senses viral DNA in cell - binds to DNA - forms cGAMP - binds to STING on endoplasmic reticulum -> transcription factor phosphorylation and movement to nucleus e.g. IRF 3 -> interferon transcription RIG also intracellular detector - RIG-I binds to viral ssRNA or mRNA => RIG-I binds to MAVS => IR3 or IR7 is phosphorylation and translocated into nucleus => transcription of interferon beta
29
How does toll-like receptor (TLR) recognise viruses
Same way as RIG except it is membrane associated so only recognises endosomes or viruses outside of cell (RIG is intracellular sensor for viruses) - detect viral RNA => IR3 or IR7 is phosphorylated => interferon transcription
30
Name two bacterial pathogens that use pyrotoxins
Staphylococcus aureus | Streptococcus pyogenes