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MCD Microbiology > 2 Bacterial Diseases > Flashcards

2 Bacterial Diseases Flashcards

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Biology 101 flashcards
1
Q

*Q: What are the sources of bacterial infection? (3)

A

A: Extrinsic - from outside you

Intrinsic - from inside you

Mythical - mythical explanations e.g. catching a cold from being outside in the cold

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2
Q

*Q: Name intrinsic sources. (6) What are they all?

A

A: non sterile sites

  • nasal cavity and sinuses / upper respiratory tract
  • mouth
  • stomach
  • small intestine / biliary tract / large intestine
  • skin
  • lower genital tract (vagina)
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3
Q

Q: What are ‘normal microbiota’?

A

A: those found normally in the body

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4
Q

*Q: What are the 2 types of infection routes/portals of entry?

A

A: expected (normal/harmless microbiota entering via an expected route eg newborn is exposed to maternal microbiota)

un-expected (normal microbiota entering unsual site OR pathogenic microbiota entering any site)

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5
Q

Q: How are pathogens that target the upper respiratory tract usually acquired? how?

A

A: extrinsically from other people as respiratory tract droplets or airborne (hand can act as intermediate)

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6
Q

Q: What is the HSV and what does it cause?

A

A: herpses simplex virus- causes cold sores (stays in nerve endins)

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7
Q

Q: What is the EBV and what does it cause?

A

A: Epstein–Barr virus- glandular fever

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8
Q

Q: What does Neisseria meningitidis cause? Vaccine?

A

A: miningococcal meningitis- but can be part of normal microbiota : can stay in pharynx

(we’ve all been vaccinated against it)

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9
Q

Q: What are the consequences of bacterial infection acquired via the upper respiratory tract? (4 subheadings- 3,3,3,1)

A

A: Upper Respiratory Tract Infection

  • Pharyngitis (back of nose and mouth)
  • Tonsilitis
  • Sinusitis

Lower Respiratory Tract Infection

  • Bronchitis
  • Pneumonia
  • Empyema (plural space)

Spread to Adjacent Tissues

  • Brain abscess (those with untreated sinusitis)
  • Meningitis
  • middle ear infection (spread from sinuses)

Spread to Blood Stream
-pneumococcal, meningococcal bacteraemia

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10
Q

Q: What are upper respiratory tract infections usually?

A

A: self limiting- eventually immune response copes with it- either innate or adapted

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11
Q

Q: What are sinuses?

A

A: air spaces in skull

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12
Q

Q: How are pathogens that target the urogenital tract acquired? What’s the most common source? Gender difference?

A

A: -extrinsic or intrinsic

  • lower bowel
  • females are more prone to getting these infections as smaller distance to reach uro. tract (particularly urethra, then bladder)
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13
Q

Q: What are the consequences of bacterial infection acquired via the urogenital tract? (4 subheadings- 2,2,1,1)

A

A: urinary tract infection

  • cystitis (bladder)
  • pyelonephritis (kidney-travelled from bladder)

genital tract infection

  • Gonococcal urethritis
  • pelvic inflammatory disease

pregnancy related infection (bad for baby)
-neonatal group B strep infection

spread to blood stream
-E coli bacteraemia

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14
Q

Q: How do pathogens enter via ‘broken skin’? (6)

A

A: -Surgery/any wound

  • skin diseases including: Varicella - chicken pox, eczema, pressure sores, burns, athletes foot
  • IVDA: Intravenous Drug Abuse
  • insect bites
  • Human bites (unexpected)
  • cannulae (hospital)
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15
Q

Q: What are the consequences of infection via broken skin? (7) Main cause?

A

A: 1. superficial infection (eg spot)

  1. If the infection spreads across the skin layer it’s called CELLULITIS - you get red inflammation of the skin
  2. Abscess - pus filled pocket
  3. Myositis - infection spread deeper into the muscle and causes inflammation
  4. Gangrene/Necrotic Infection - any layer of skin or soft tissue can be subject to necrosis (=cell death underneath the superficial layer)
  5. Bacteraemia
  6. fasciitis- layer below skin (connective tissue between skin and muscle)

STAPH AUREUS

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16
Q

Q: What are the disease consequences of bacterial infection acquired via the GI tract? (6)

A

A: Diarrhoeal illnesses

  • vomiting
  • diarrhoea
  • dysentry (blood diarrheoa- suggests invasive infection that caused gut wall to bleed)

Bacteremia/Systemic Infections

  • Listeriosis (Lysteria monocytogenes)
  • Salmonellosis and septic arthritis, aortitis

toxin mediated disease
-D and V (eg aureus enterotoxin)

17
Q

Q: Why is Listeria problem?

A

A: Listeria isn’t a major cause of diarrhoea and vomiting but if it gets into the blood stream it can cause serious disease in neonates, the elderly and people who are immunocompromised

18
Q

Q: What do toxins tend to cause in the GI tract?

A

A: vomiting type illnesses

19
Q

Q: What is pathogenicity of bacteria? 3 groups? 3 examples?

A

A: ability of a bacterium to cause disease

  • Commensals - don’t cause disease eg lactobacillus in vagina and GI tract
  • True Pathogen - can cause disease in normal, healthy people eg staphylococcus aureus from skin causing large abscess and bacteraemia
  • Opportunistic Pathogen - can only cause disease when they are given the chance (if it’s given a leg up) eg staphylococcus epidermidis from skin causing prosthetic hip joint infection
20
Q

*Q: What affects pathogenicity? (5)

A

A: Infectivity - the ability to get into the host system and establish themselves

-> Complete immune evasion

Virulence - features that enhance disease causation - enhance the bugs ability to make you unwell

Toxins

Enzymes

21
Q

*Q: What are the factors involved in infectivity? (4)

A

A: -Transmission to host

  • Ability to colonise host
  • Ability to find unique niche (place in body)
  • Ability to replicate
22
Q

*Q: What are the factors involved in virulence? (4)

A

A: -Toxin production

  • Enzymes that degrade host molecules
  • Complete immune evasion
  • interruption of normal host processes
23
Q

*Q: What is the infective dose? What affects it? (4)

A

A: number of bacteria/pathogen required to initiate an infection

  • Route of Transmission - e.g. stomach acid means that higher infectious dose is usually required
  • Tropism and Motility
  • Replication Speed
  • Immune Evasion
24
Q

Q: Mycobacterium tuberculosis. Infective dose? Replication rate? What increases pathogenicity? (2)

A

A: low infective dose, low replication rate, can survive inside macrophages and resist killing

25
Q

*Q: Describe features that enhance disease causation (virulence) in Streptococcus pneumoniae. (2)

A

A: Toxin Production - e.g. pneumolysin: cholesterol dependent pore forming toxin affecting lung architecture

Degradation of Host Molecules e.g. hyaluronan lyase-degrades host hyaluronic acid matrix for nutrition and spreads

26
Q

*Q: Describe features that enhance disease causation (virulence) in S aureus. (2)

A

A: Interference with Host Cell Function - e.g. superantigens interfere with normal T cell function (cause immune system to make too many cytokines -> sends body into toxic shock)

Immune Evasion - e.g. S. aureus makes leukocydins which causes neutrophil death and abscess formation

27
Q

*Q: What causes tonsilitis? Transmission?

A

A: Strep. pyogenes -mouth: droplet transmission

28
Q

*Q: What causes Meningococcal sepcticaemia? Transmission?

A

A: Neisseria meningitidis colonises the nasopharynx asymptomatically before invading epithelial, then endothelial cells
-mouth: droplet transmission

29
Q

Q: What causes pneumonia? Where?

A

A: Strep pneumoniae- respiratory tract

30
Q

Q: What causes nasal sinuses and into brain? (2)

A

A: S. pneumoniae, Haemophilus influenzae

31
Q

*Q: What’s the transmission of cholera? Vibrio cholerae. Infective dose? Movement? Produces? (2) role? result? symptom?

A

A: Faeco-oral

  • HUGE INFECTIVE DOSE
  • Use flagella to penetrate mucus
  • Makes 2 component toxins A + B -> bind to GM gangliosides on gut -> triggers production of cAMP -> CHLORIDE EFFLUX (ion exchange between gut epithelial cells and gut luminal)-> Sodium ions and water flood out leading to rice water stools
32
Q

*Q: Describe genital tract colonisation with group B strep (from GI tract). 3 results?

A

A: leads to invasive group B strep infection in neonates:

meningitis, septicaemia, death

33
Q

Q: How does Staphylococcus aureus enter? What does it cause?

A

A: - through the skin

-Produces a family of leukocydins - toxins which destroy neutrophils producing characteristic pus

34
Q

Q: Name 7 Gram negative pathogens.

A

A: -neiseria (miningitidis and gonorrhoeae)

  • haemophilus influenzae
  • escherichia coli (EPEC, EHEC, ETEC, UPEC)
  • salmonella spp.
  • vibrio cholerae
  • shigella
35
Q

Q: Name 10 Gram positive pathogens.

A

A: -staphylococcus aureus

  • streptococcus
    • > Group A= S. pypgenes
    • > Group B= S. agalactiae
    • > Viridans strep= dental bacteria
    • > Pneumococcus = S. pneumoniae
  • clostridium (difficile, tetani, botulinum, pergringens)
  • listeria spp.
36
Q

Q: Name 2 opportunistic gram negative bacterial pathogens.

A

A: pseudomonas aeruginosa
-eg. indwelling long term urinary catheters and multiple UTIs previously treated with antibiotic

acinetobacter baumanii
-eg. open battlefield trauma heavy prophylaxis with broad sprectrum antibiotics followed by ICU stay and nosocomial transmission

37
Q

Q: Name 2 opportunistic gram positive bacterial pathogens.

A

A: staphylococcus epidermidis
-eg. prosthetic joint and valve infections, metal work, central line infections

enterococcus
-eg. abnormal heart valves

38
Q

Q: List 7 sources of bacteria.

A

A: 1. Upper respiratory tract (intrinsic + extrinsic)

  1. Lower GI tract (intrinsic + extrinsic)
  2. Sexual/Urogenital tract (intrinsic + extrinsic)
  3. Skin (intrinsic + extrinsic)
  4. Nosocomial/Hospital Acquired (all of the above)
  5. Food and Water
  6. Animals

MCD Microbiology (12 decks)

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