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Y2 Microbiology > Community acquired bacterial infections > Flashcards

Community acquired bacterial infections Flashcards

1
Q

What are the main groups of bacterial shapes

A

Cocci (spherical)
Bacilli (rod)
Budding and appendaged bacteria
Others

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2
Q

Give examples of cocci shapes

A 
Coccus (single)
Diplococci (double) + encapsulated (pneumococcus)
Streptococci (chain)
Staphylococci (rows)
Sarcina (four, two layers)
Tetrad (four)
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3
Q

Give examples of bacilli shapes

A 
coccobacillus (oval shaped)
Bacillus (single)
Diplobacilli (double)
Palisades (side by side lengthways)
Streptobacilli (chain)
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4
Q

Give examples of Budding + appendaged bacteria shapes

A

Hypha

Stalk

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5
Q

Give examples of common bacterial virulence factors

A 
Secretion systems
Flagella
Pili
Capsule
Endospores
BIolfilms
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6
Q 
Explain how the following contribute to virulence:
Secretion systems
Flagella
Pili
Capsule
Endospores
BIolfilms
A

Diverse secretion systems - as they move molecules towards the exterior of cells -

Flagella - movement and attachment

Pili (smaller, hair-like projections) - attachment

Capsule - protection against phagocytosis e.g. Streptococcus pneumoniae

Endospores - resistant to heat and cold, desiccation - (dryness) and chemicals

Biofilms - antibiotic resistant

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7
Q

What is a biofilm

A

organised aggregates of bacteria embedded in a polysaccharide matrix which is antibiotic resistant e.g. Pseudomonas aeruginosa, Staphylococcuqs epidermidis

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8
Q

What are endospores

A

metabolically dormant forms of bacteria, resistant to heat and cold, desiccation - (dryness) and chemicals e.g. Bacillus sp. (species), Clostridium sp.

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9
Q

What are exotoxins and what are the types

A

proteins released as free molecules by bacteria:
Neurotoxins
Enterotoxins

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10
Q

What do neurotoxins act on and give examples of bacteria that might produce them

A

act on nerves or motor endplates e.g. Clostridium tetani or C. botulinum toxins

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11
Q

What do enterotoxins act on and what pathologies may they cause (+ examples of bacteria that may cause each)

A

act on the GI tract, causing infectious bacteria diarrhoea (bacteria are alive - E. coli) or food poisoning (bacterial toxins from food were not destroyed by cooking - S. Aureus)

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12
Q

What are the two types of exotoxins (other than neurotoxins and enterotoxins)

A

Pyrogenic exotoxins - stimulate release of cytokines, e.g. Strep. pyogenes, Staph. aureus

Tissue invasive exotoxins -enzymes that allow bacteria to destroy and tunnel through tissue e.g. - Strep. pyogenes, Staph. aureus, Clostridium perfringens

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13
Q

What are endotoxins

A

Endotoxins are antigens that the immune system responds to to combat such bacteria

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14
Q

Which grams stain bacteria can produce endotoxins and why

A

Endotoxins can only be produced by Gram-negative bacteria, because they’re not free molecules but rather the lipid A moiety of lipopolysaccharides from bacterial outer membranes. They are shed steadily from living bacteria

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15
Q

What are the risks of endotoxins

A

Lysing the bacteria (e.g. with antibiotics) can cause sudden release of large quantities of endotoxin, thus worsening any septic shock.

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16
Q

Define outbreak

A

A greater-than-normal or greater-than-expected number of individuals infected or diagnosed with a particular infection in a given period of time, or a particular place, or both

17
Q

What is important in the identification of an outbreak

A

Good, timely reporting systems are instrumental for identifying outbreaks.
After reporting, the cause of an outbreak must be confirmed and it must be ensured that there are no other causes.

18
Q

What are the 6 categories of communicable diseases in Europe

A
  • respiratory tract infections
  • sexually-transmitted infections, including blood-borne viruses
  • food- and water-borne diseases and zoonoses
  • emerging and vector-borne diseases
  • vaccine-preventable diseases
  • drug-resistance and healthcare-associated infections
19
Q

Give examples of respiratory tract infections

A

Influenza (swine and bird)
Mycobacterium tuberculosis
Legionella pneumophilia

20
Q

Describe mycobacterium tuberculosis

A

(called Gram-positive but has another lipid layer in its cell
- wall, making treatment difficult)
Can also become dormant, leading to ‘latent tuberculosis’
Where immunological evidence of current infection exists without clinical signs or symptoms

21
Q

Describe legionella pneumophilia

A

lives in ponds, lakes, and air conditioning units, and infects hosts - via inhalation of contaminated aerosols.
Its type IV secretion system then allows Legionella to survive and replicate in vacoles inside alveolar macrophages (causes Legionnaires’ disease)

22
Q

Give examples of sexually-transmitted infections

A 
Chlamydia trachomatis
Neisseria gonorrhoea
Treponema pallidum (syphillis)
Hep B and C
HIV
23
Q

Describe chlamydia trachomatis

A

Most common STI in Europe
Responsible for more than 3% of world blindness, infecting tens of millions of people’s eyes
An obligate intracellular pathogen so cannot be cultured outside the host cells.

24
Q

Describe neisseria gonorhoae

A

Establishes infection of the urogenital tract via non-ciliated epithelial cells
Important virulence factors are its pili and the antigenic variation that help it escape immune detection and clearance.

25
Q

Give examples of food and water-borne diseases and zoonoses

A 
Campylobacter
Salmonella
Cholera toxin (from vibrio cholerae)
Listeria monocytogenes
Escherichia coli
Clostridium botulinum
Shigella dysenteriae
Bacillus anthracis
Giardia (parasite) - traveller's diarrhoea
26
Q

Describe campylobacter

A

Most commonly reported GI infection in the EU.
Cases are usually sporadic rather than outbreaks, and tend to affect 0-4 year-olds.
Undercooked poultry is the most likely source. It has many important virulence factors.

27
Q

Describe salmonella

A

sp. infects small children mostly via undercooked poultry, but outbreaks of it do occur.
Type III secretion systems on pathogenicity islands are crucial virulence factors.

28
Q

Describe cholera toxin

A

causes upregulation of a Cl- channel (CFTR) in the GI epithelium, causing severe, acute dehydration.
The most recent outbreak was in Haiti.

29
Q

Describe listeria monocytogenes

A

Can enter non-phagocytic cells and cross tight barriers, allowing it to penetrate the intestinal barrier, blood-brain barrier, and placenta.
Listeria’s intra- and intercellular movement (which creates ‘comet trails’ of actin) is a popular research topic.

30
Q

What is typhoid fever caused by

A

Salmonella enterica enteric of the serotype ‘typhi’

31
Q

Give examples of emerging and vector-borne diseases

A 
Malaria
Plague(there are three types of the plague, bubonic is just one) SARS (severe acute respiratory syndrome)
Smallpox
West Nile fever
Yellow fever
32
Q

What is malaria caused bu

A

Plasmodium parasite

33
Q

What was plague caused by

A

Yersinia pestis

34
Q

Give examples of vaccine-preventable diseases

A 
Corynebacterium diphtheriae (diphtheria) 
Clostridium tetani (tetanus)
Bordetella pertussis (pertussis)
Neisseria meningitidis (meningitis)
Haemophilus influenzae
measles
mumps
rubella
poliomyelitis (polio)
rabies

Y2 Microbiology (7 decks)

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