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Year One - Principles of Disease > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What are the three domains of life?

A

Bacteria

Archaea

Eucarya

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2
Q

Is bacteria a prokaryote or a eukaryote?

A

Prokaryote

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3
Q

Is archaea a prokaryote or a eukaryote?

A

Prokaryote

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4
Q

Is eucarya a prokaryote or a eukaryote?

A

Eukaryote

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5
Q

What are the five causes of infection?

A

Parasites

Fungi

Bacteria

Viruses

Prions

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6
Q

What are parasites?

A

Organisms that live in, with or on another organism and derives its nutrients at the expense of the host.

They can be vector of infection or cause vectors themselves.

Eukaryotes

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7
Q

What are fungi?

A

Saprophytic (get energy from dead and decaying matter) and spore producing organisms.

Eukaryotes

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8
Q

What are bacteria?

A

Round, spiral or rod-shaped single celled organisms.

Prokaryotes

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9
Q

What are viruses?

A

Unique, single celled metabolically inhert organisms.

Only replicate within living cells.

Unclassified

Most viruses have a specific host range and only infect specific host cell types - tissue tropism

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10
Q

What are prions?

A

Prions are proteins of unknown function found on the surface of brain cells.

Unclassified

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11
Q

What are the two sites that we can collect culture from?

A

Sterile - blood, CSF, brain cells

Non-sterile - skin cells

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12
Q

What culture site is more significant when identifying infections?

A

Sterile sites

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13
Q

What are the advantages of microscopy when identifying infections?

A

Rapid

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14
Q

What are the disadvantages of microscopy when identifying infections?

A

Not a specific technique

Clarify results with other forms of tests

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15
Q

What are the four types of microscopy?

A

Light - identifies all infections, except viruses

Unstained - views all WBCs and parasites

Gram stain - views bacteria and fungal cells

Special stains (Ziehl Neelsen/Auramine) - mycobacteria

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16
Q

What is a healthcare associated infection?

A

The onset of infection following 48 hrs of admission into hospital or recent healthcare contact

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17
Q

What is a virion?

A

Extracellular form of a virus. Exists outside host and facilitates transmission from one host to another.

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18
Q

Describe the structure of a virion.

A

Consist of a nucleic acid, which has virion associated polymerase attached to it.

Nucleic acid is surrounded by a protein caspid.

Some virions have a lipid envelop around the protein caspid. Lipid envelope has proteins in attached to it which are made from the host cell’s materials and allow them to evade the immune system.

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19
Q

What four things classify virus families?

A

Virion shape

Presence of envelope

Genome structure

Mode of replication

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20
Q

Describe the process of virus replication.

A
  1. The virus antigens attach to the host cell’s surface
  2. The virus enters the host cell and is uncoated, which means that its lipid envelope is removed if it has one
  3. The virus then inserts its nucleic acid into the host cell’s DNA. The host cell’s DNA is then replicated, which means that the virus’s nucleic acid is also replicated

4 .The virus’s genes are then transcribed init mRNA and then translated into viral protein coats

  1. The new nucleic acid then enters the newly formed protein coats to produce several viruses. These viruses then burst out of the host cell by undergoing lysis.
  2. The cycle continues
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21
Q

What are the multiple routes of virus transmission?

A

Blood-Borne

Sexually

Vertical

Faecal-Oral

Droplet

Close Contact

Vector-Borne

Zoonotic

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22
Q

What happens when a virus can infect humans and other animals?

A

Different strains of the virus can arise in the different types of organisms. These strains can connect and recombine in the one organism and generate a new strain.

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23
Q

What are the features of influenza A virus?

A

An example of an acute viral infection.

The virus infects cells of the respiratory tract and alter cytokine expression. This results in feverish symptoms.

If they destroy the respiratory epithelium, it can lead to secondary bacterial infections.

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24
Q

How do variations of viruses arise?

A

Antigenic shift - abrupt, major changes in virus antigenic structure

Antigenic drift - minor changes in the genes that occurs gradually over time to generate antigenic variants

25
Q

What are enteroviruses?

A

Viruses the are shed in respiratory secretions, stool and sometimes are present in blood and CSF of infected patients.

Infection is transmitted by direct contact with respiratory secretions or stool.

26
Q

What is a latent virus infection?

A

A type of persistent viral infection. Latency is the phase in viruses life cycle after initial infection where proliferation of the virus stops. However, the viral genome is not eradicated. This means that it can be reactivated without the host becoming re-infected.

27
Q

What is an example of a latent virus infection?

A

Herpes simplex virus

28
Q

What is an asymptomatic viral infection?

A

An infection is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms

29
Q

What is are virus-induced tumours?

A

Viruses replicate their nucleic acid into host cells and lead to abnormalities that result in tumour formation. These abnormalities include modulating cell cycle or apoptosis.

30
Q

What are the four consequences of viral infection?

A

Clearance of virus leads to no short or long term immunity

It can result in chronic infection or cancer.

It can result in latent infection

The virus can undergo antigenic variation - leads ti long term infection

31
Q

Which group of patients are latent viruses more likely to affect?

A

Immunocompromised

32
Q

Name the five methods used to detect viruses.

A

Microscopy - detect whole virus

Culture - detect whole virus

ELISA - detect antigens on the surface of the virus

Extraction of genetic material - detect the viral DNA/RNA

Immune response

33
Q

Are all antiviral agents virustatic or viricidal?

A

All are virustatic, which means that they stop the growth of viruses

34
Q

Are side effects to antiviral therapy common?

A

Yes

35
Q

What can antiviral therapy used for?

A

Prophylaxis - to prevent infection

Pre-emptive therapy - evidence go infection or replicated detected before symptoms are apparent

Overt disease - symptoms are apparent

Suppressive therapy - keep viral replication below the rate that causes tissue damaged in an asymptomatic infected patient

36
Q

What are the five ways in which we can prevent viral infection?

A

Immunisation - actively through vaccinations or passively through antibodies

Prophylactic treatment post exposure - intended to prevent future infection

Infection prevention and control measures

Blood, tissue or organ screening

Antenatal screening

37
Q

What are the three main types of parasites?

A

Protozoa
Helminths
Ectoparasites

38
Q

What are protozoa?

A

Microscopic, single-celled organisms that can be free-living or parasitic in nature

Able to replicate in humans and can live within the intestine, blood or tissue

If they live in the intestine they are transmitted through faecal-oral route. However, if they live in the blood or tissue, they are transmitted through an insect vector.

39
Q

What is an example of a protozoan infection? Describe its features?

A

Malaria.

A mosquito-borne disease caused by a parasite called plasmodium. The plasmodium has to spend part of their lifecycles in humans (intermediate host) so that they can develop into male and female forms which are ready to infect a mosquito (definitive host).

40
Q

What are two other protozoal infections?

A

Amoebic dysentery, which is transmitted via the faecal oral route

Leishmaniasis, which is transmitted via a vector

41
Q

What are the three divisions of the helminth category?

A

Nematodes (roundworms)

Cestodes (tapeworms)

Trematodes (flatworms)

42
Q

How are nematodes transmitted? Name two examples.

A

Faecal-oral route

Pinworm. Parasite lays eggs in perianal folds. The embryonate eggs are then ingested by the human and hatch in the small intestine. The adult larvae then migrate to the perianal region to lay eggs. Cycle continues.

Ascaris lumbricoides. Infection leads to developmental delay in children and can cause severe complications due to the roundworms obstructing the bowel.

43
Q

How are custodies transmitted? Name two examples.

A

Eating raw/undercooked meat.

Beef and pork tapeworms. Both tapeworms have two hosts; cattle and pig (intermediate host) and humans (definitive host). The tapeworm eggs in faeces are passed into the environment. Cattle and pigs become infected by ingesting the eggs. The humans then ingest the infected meat. In the small intestine, the tapeworms develop into adults and lay eggs. The eggs are passed out in the faces. Cycle continues.

44
Q

How are termatodes transmitted? Name an example of a trematode.

A

Freshwater

Schistosoma, which causes schistosomiasis in humans. This parasite needs to spend part of its lifestyle in a snail (intermediate host) so that it can develop into a larval form. This larval form can penetrate the skin of a human, which is the parasites definitive host and where it will undergo sexual maturity.

45
Q

What are ectoparasites?

A

Parasites that live outside the body.

46
Q

Name the five methods we can use to detect parasites.

A

Blood microscopy

Stool microscopy

Eosinophillia & IgE levels

Serology

Rapid Diagnostic Tests

47
Q

Are fungi present in and on our body normally? When do they start to cause problems?

A

Yes.

When they increase in numbers and when individuals are immunocompromised

48
Q

Describe the structure of a fungus?

A

Cell wall contains polysaccharides and is able to absorb nutrients

Cell membrane contains lipids, such as ergosterol

49
Q

How do we classify fungi?

A

Based on morphology - structure

The way that they produce spores

50
Q

What are the three main groups of fungi?

A

Basidiomycetes

Ascomycetes

Zygomycetes

51
Q

What types of spores do all three groups of fungi produce?

A

Sexual and asexual, sexual spores are the ones that cause disease in humans

52
Q

What are basidiomycetes?

A

Fungi that have a main body called the basidium, which is the reproductive organ of the fungi and therefore involved in spore-production

53
Q

What are ascomycetes?

A

Fungi that form an ascus, which is a sac-like structure that contains the ascopsores. Therefore, spore production occurs in the sac

54
Q

What are zygomycetes?

A

Rough-walled zygotes, with their rough cell wall producing spores

55
Q

What are yeasts?

A

Yeasts are single-celled fungi. They divide through an asexual process known as budding. They belong to all three of the classifications.

56
Q

What are dermatophytes?

A

A pathogenic fungus that grows on skin, mucous membranes, hair, nails and other body surfaces. They cause ringworm and related diseases.

57
Q

How do we treat dermatophytes?

A

Drugs or topical treatments that contain enzymes that degrade keratin. This is because keratin is needs for the growth of the dermatophytes.

58
Q

What are candida?

A

Type of yeast that cause candida infections in seriously immunocompromised hosts and unusual endocrine and immune dysfunction.

59
Q

How can we detect fungal infection?

A

Histopathology

CT scans

Year One - Principles of Disease (15 decks)

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