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Immunology and Infection > Microbial Infections > Flashcards

Microbial Infections Flashcards

1
Q

How many Ebola case free days does a country need to go through before the outbreak being declared over?

A

42 days

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2
Q

What animal is believed to have introduced the Ebola virus into the human population?

A

Hammerhead Bat (Hypsignathus monstrosus)

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3
Q

Why did Ebola not kill the animal acting as a reservoir?

A

Ebola virus entry requires the cholesterol transporter Niemann-Pick C1 (Npc1). Some hammerhead bats have a mutation in this enzyme leading to low-grade viral infection and carrier status.

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4
Q

What virus is being used to develop Ebola and Covid vaccines?

A

The Recombinant Vesicular Stomatitis Virus rVSV. The vaccine is a vectored vaccine whereby Ebola/SARS COV 2 surface glycoproteins are expressed on the surface of rVSV.

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5
Q

What are viruses classified as?

A

Obligate parasites

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6
Q

How do viruses divide and how can you characterise their behaviour?

A

The divide by budding out of host cells or cytolysis. The show host specificity but can infect almost all other life forms including bacteria.

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7
Q

What type of virus is HIV?

A

HIV is a retrovirus (RNA genome)

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8
Q

What are the different routes of infection for viruses?

A

Oral-faecal, bloodborne, airborne, insect vectors.

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9
Q

Identify and recall the following structures of Bacteria.

A
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10
Q

What are the characteristics of prokaryotes?

A

Do not have internal membranes (apart from photosynthetic bacteria). A single copy of a chromosome. Poorly defined cytoskeleton. Peptidoglycan cell wall. Divide by binary fisiion.

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11
Q

What is the function of the pilus, capsule and flagellum?

A

The pili help in adhering to surfaces. Capsules help prevent desiccation or phagocytosis. Flagella are important for swimming.

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12
Q

What are the bacteria we need to know about in this module?

A

Shigella, Neisseria meningitidis, Clostridium difficile, Methicillin-Resistant Staphylococcus aureus and Mycobacterium tuberculosis.

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13
Q

What is an infectious dose of Shigella?

A

10-100 bacteria

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14
Q

What is the transmission pathway of Shigella?

A

faecal-oral

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15
Q

How do shigella move to avoid phagocytosis?

A

Shigella do not have flagella. They nucleate the host cell actin at their tale to move around.

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16
Q

How do shigella infect other cells once in the body?

A

They use the host cell actin to move around within the cytoplasm of an infected cell and eventually into neighbouring cells as well. This allows them to infect a whole monolayer of cells without having to go outside the cell.

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17
Q

What part of the body does shigella infect?

A

GI tract and in severe cases can cause huge amounts of tissue damage leading to death.

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18
Q

What type of microbe is Neisseria meningitidis?

A

N. meningitidis can be a commensal (harmless) microbe that lives in the nasopharynx of about 20% of the population but can also cause severe disease.

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19
Q

What parts of the body can N. meningitidis invade?

A

It can invade the tissues, blood and penetrate the blood-brain barrier into the cerebrospinal fluid.

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20
Q

What happens when N. meningitidis invades tissues?

A

It can cause a characteristic non-blanching rash (does not fade under pressure).

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21
Q

What happens when N. meningitidis invades the blood-stream?

A

It can cause rapid septicaemia with a severe inflammatory response and a 10% fatality rate.

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22
Q

What happens when N. meningitidis penetrates the blood-brain barrier?

A

It enters the cerebrospinal fluid and can cause meningococcal meningitis.

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23
Q

Describe the onset of symptoms in N. meningitidis.

A

It can be a medical emergency with a rapid onset of symptoms from the first signs of a non-blanching rash. Infections can leave people with severe disabilities.

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24
Q

What kind of infection is N. meningitidis and amongst what group is it most common?

A

It is a community-acquired infection and is most common amongst babies and young adults.

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25
Q

What are serogroups?

A

A group of bacteria that have a common antigen.

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26
Q

Are there any N. meningitidis vaccines available?

A

Yes, vaccines are widely available to a wide range of different serogroups associated with the infection.

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27
Q

What are hospital-acquired infections often associated with?

A

antimicrobial resistance (AMR).

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28
Q

What are some examples of hospital-acquired infections?

A

Clostridium difficile and Methicillin-Resistant Staphylococcus aureus.

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29
Q

What is the most lethal infectious disease worldwide?

A

Tuberculosis caused by Mycobacterium tuberculosis.

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30
Q

What are the limitations of TB treatment/prevention?

A

Current drug therapy takes too long (six months), the BCG vaccine does not work well in endemic regions, the current diagnostics miss too many cases failing to break the chain of transmission.

31
Q

How have new imaging tools helped understand the pathogenesis of TB?

A

PET/CT can show areas of inflammation at high resolution making it a marked improvement from X-rays.

32
Q

What is Helicobacter pylori associated with?

A

Peptic ulcers and gastric cancer.

33
Q

What type of microbe is Escherichia coli?

A

Usually a commensal (harmless) gut microbe in human sand many other animals. However, some types cause severe disease and develop pathogenic traits.

34
Q

What is the transmission pathway of E. coli?

A

Pathogenic E. coli often originate in other animals and are spread to humans by the faecal-oral route.

35
Q

How do bacteria and viruses evolve so quickly?

A

Viruses have higher mutation rates and generation time compared to humans. Bacteria have a higher generation time compared to humans.

36
Q

Why do viruses have a higher mutation rate compared to bacteria and humans?

A

Humans, vertebrates and bacteria have constant mutation rates because the polymerases used can correct any errors that occur. Viruses have error-prone replication that can’t correct errors with very high efficiency. Bacterial is more prone to mutations compared to humans though because only one gene needs to be mutated to have a phenotypic effect.

37
Q

How does a shorter generation time lead to faster mutation/evolution?

A

Shorter generation times means genes can be selected for and spread in a population much quicker. Even though bacteria and humans have similar mutation rates, bacteria evolve faster because they go through more mutations as a result of shorter generation times.

38
Q

What do retroviruses need to successfully replicate within hosts?

A

Reverse transcriptase.

39
Q

What disease were these used to treat?

A
  • Used to treat polio patients
  • Iron lungs that worked as negative pressure changers to help polio patients breathe.
40
Q

What enzyme is essential for HIV to infect cells?

A

HIV is a retrovirus with an RNA genome and requires reverse transcriptase to convert its RNA genome into DNA.

41
Q

What infection does HIV cause?

A

Acquired Immune Deficiency Syndrome.

42
Q

What condition is this and what infectious agent is it caused by?

A
  • Smallpox caused by Variola Virus.
  • Only infectious disease to be eradicated by vaccinations.
43
Q

What can the Human Papilloma Virus potentially cause?

A

Cervical cancer

44
Q

What type of mycoses (fungal infections) can Fungi cause?

A

Cutaneous (skin-related), mucosal and/or systemic mycoses

45
Q

What forms can Fungi occur as during their life cycles?

A

Yeasts, filaments or both

46
Q

How can yeasts replicate?

A
  • Yeasts can bud or divide
  • Filaments (hyphae) have cross walls or septa
47
Q

What are well-known examples of fungal pathogens?

A

Candida albicans and Aspergillus fumingators

48
Q

What are protozoa?

A

Unicellular eukaryotic organisms

49
Q

Protozoa include what kinds of parasites?

A

Intestinal, blood and tissue parasites.

50
Q

How do protozoa replicate?

A

They replicate in the hos by binary fission or by the formation of trophozoites inside a cell.

51
Q

What kind of lifecycles can protozoa have?

A

They can have complicated lifecycles involving two hosts.

52
Q

How is a protozoa infection acquired?

A

Through ingestion or through a vector

53
Q

What are some examples of protozoa infections?

A

Malaria and Leishmaniasis.

54
Q

What causes malaria and how is it transmitted?

A
  • Plasmodium species (protozoa) cause malaria.
  • Blood and tissue parasite that forms trophozoites inside a cell
  • Infection acquired via a mosquito vector.
55
Q

What impacts the distribution of malaria around the world (the malaria belt)?

A

The distribution of the mosquito species required to complete the parasite lifecycle and transmit to new hosts.

56
Q

What is shown in this image?

A
  • Trophozoites inside the cell
  • Parasite replicates and forms feeding structures
  • Feeding structures produce lots of progeny which then lyse and release other stages into the bloodstream associated with the fever that is characteristic of malaria.
57
Q

What species of Leishmania cause disease in humans?

A
  1. Leishmania donovani
  2. Leishmania tropica
  3. Leishmania braziliensis
58
Q

What type of disease does Leishmania donovani cause?

A

A visceral disease known as kala-azar.

59
Q

What type of diseases do Leishmania tropica and braziliensis cause?

A

Cutaneous types of infections

60
Q

How is leishmaniasis acquired and what are the characteristics of Leishmania?

A
  • Acquired via a sandfly vector.
  • Blood and tissue parasites.
  • Form trophozoites inside a cell.
61
Q

What are Helminths?

A
  • Metazoan (cells differentiated into tissues and organs) Multicellular Eukaryotic organisms.
  • Large enough to be visible to the naked eye.
62
Q

What are some common examples of helminth parasites?

A
  • Roundworms
  • Tapeworms
  • Flatworms (Flukes)
63
Q

What does this image show and what are the consequences of infections like these?

A
  • Complete obstruction of the intestine with Ascarid roundworms.
  • This can lead to malabsorption of nutrients and malnutrition.
64
Q

What treatment is available for Ascarid roundworms infections?

A
  • Chemotherapy is available but not very efficient.
65
Q

What helminths do require an intermediate host?

A
  • Flukes like Schistosomes
66
Q

What is the condition depicted in the picture and what causes it?

A

This is schistosomiasis caused by the release of schistosoma in the hepatic portal vein which then migrate into tissues.

67
Q

What intermediate hosts do schistosomes require?

A

Water snails

68
Q

What treatment/intervention is available for schistosomiasis?

A
  • Antimicrobial treatment.
  • Programmes to remove fresh-water snails.
69
Q

Summary of viruses

A
  • Not cells in their own right
  • Obligate Parasites
  • Contain RNA or DNA as genetic material
  • Replicate using host-cell nuclear synthetic machinery
  • Show host specificity
  • but infect almost all other life forms, including bacteria
  • Divide by budding out of host cell, or cytolysis
  • Various routes of infection
  • Faecal-oral, airborne, insect vectors, blood borne
70
Q

Summary of Bacteria

A
  • Prokaryotes do not have internal membranes
  • photosynthetic bacteria are an exception
  • eukaryotes have internal membranes that define organelles including nucleus, ER, mitochondria
  • Prokaryotes have a single copy of a chromosome (haploid)
  • eukaryotes can be haploid or diploid
  • Prokaryotes cytoskeleton is poorly defined.
  • Eukaryotic cells have well developed cytoskeleton
  • Prokaryote cell wall contains peptidoglycan
  • Prokaryotes divide by binary fission
71
Q

Summary of Fungi

A
  • Eukaryotic
  • cause cutaneous, mucosal, systemic mycoses
  • occur as yeasts, filaments or both
  • yeasts bud or divide
  • filaments (hyphae) have cross walls or septa
72
Q

Summary of Protozoa

A
  • Unicellular eukaryotic organisms
  • include intestinal, blood and tissue parasites
  • replicate in the host by binary fission or formation of trophozoites inside a cell
  • many have a complicated life cycle involving two hosts
  • infection is acquired by ingestion or through an insect or invertebrate vector
73
Q

Summary of Helminths

A
  • Metazoa with eukaryotic cells
  • Multi-cellular; visible to the naked eye
  • Life cycles outside the human host
  • Roundworms e.g. Ascaris
  • Flatworms (flukes)
  • Tapeworms

Immunology and Infection (3 decks)

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