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Year 2 MCD Microbiology > 2: Bacterial Infections (Community and Hospital Aquired diseases) > Flashcards

2: Bacterial Infections (Community and Hospital Aquired diseases) Flashcards

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Biology 101 flashcards
1
Q

What is an outbreak?

A

An outbreak is 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.
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2
Q

How can an outbreak be identitfied?

A
  1. Surveillance provides an opportunity to identify outbreaks
  2. Good and timely reporting systems are instrumental to identify outbreaks
    • possible epidemic case
      • shows symptoms + has E.coli strain
    • probable epidemic case
      • symptoms+ was in germany (area of infection)
    • confirmed epidemic case
      • genome sequencing confirmned
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3
Q

List important bacterial virulence factors

A
  1. Diverse secretion systems (e.g. can inject proteins into host cell)
  2. Flagella (movement, attachment)
  3. Pili (important adherence factors)
  4. Capsule (protect against phagocytosis)
  5. Endopores(metabolically dormant forms of bacteria) –> heat, cold, desiccation and chemical resistant
  6. Biofilms (organized aggregates of bacteria embedded in polysaccharide matrix – antibiotic resistant)
  7. Exotoxins
    1. neurotoxins
    2. enterotoxins
    3. Pyrogenic exotoxins
    4. more
  8. Endotoxins
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4
Q

What are exotoxins?

A

Different toxins (proteins) produced by bacteria that can have a virulent effect

Many different types with many different targets

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5
Q

Name classes of Exotoxins and examples of which bacteria they are produced by

A
  1. Neurotoxins (act on nerves or motor endplate)
    1. i.e. Tetanus or Botulinum toxins
  2. Enterotoxins (act on the GI tract)
    1. Infectious diarrhea
      • i.e. Vibrio cholera, Escherichia coli,
    2. Food poisoning
      • Staphylcoccus aureus
  3. _Pyrogenic exotoxin_s (stimulate release of cytokines)
    • i.e. Staphylcoccus aureus or Streptococcuspyogenes
  4. Tissue invasive exotoxin (allow bacteria to destroy and tunnel through tissue) via enzymes that destroy DNA, collagin, fibrin, NAD, red or white blood cells
    1. i.e. Staphylococcus aureus, Streptococcus pyogenes
  5. Miscellaneous exotoxin (specific to a certain bacterium and/or function not well understood)
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6
Q

What are endotoxins?

A

Lipo-polysaccarides on surfaces of Gramm -ve bacteria

  • shed in steady amounts by living bacteria
  • sometimes: treat with ABX causes even more release of Endotoxins and leads to Septic shock
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7
Q

What are the Characteristics of a possible epidemic case?

A
  • onset after onset of epidemic
  • Development of symptoms
      • laboratory criteria
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8
Q

What is a probable epidemic case?

A

Any person meeting criteria for possible epidemic case

+

  • during the last 14 days has been exposed to source of pathogen (e.g. was in germany, ate food from germany, contact with infected person )
    *
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9
Q

What is a confirmed epidemic case?

A

Any person meeting criteria for possible case +

  • isolation of pathogenic
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10
Q

What are the different classes of communicable diseases?

A

1) Respiratory tract infections
2) Sexually transmitted infections, including HIV and blood-borne viruses
3) Food- and waterborne diseases and zoonoses
4) Emerging and vector-borne diseases
5) Vaccine-preventable diseases

–> Community Aquired

  • 6) Antimicrobial resistance and healthcare-associated infections*
  • –> Healthcare Aquired*
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11
Q

Name examples of bacterial respiratory tract infections

A
  • Legionnaires’ disease (legionellosis)
    • Legionella pneumophila (Gram -)
  • Tuberculosis
    • Mycobacterium tuberculosis (Gram +)
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12
Q

What are the characteristics of Legionella pneumophila?

A
  • Gramm -ve
  • ROI: Airborne (inhalation of contaminated aerosoles)
    • infects and growth in alveolar macrophages
    • virulence via Secretion type IV ( allow Legionella to replicate in a Legionella containing vacuole (LCV))
      *
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13
Q

What are the characteristics of Mycobacterium tuberculosis?

A
  • Gramm +ve
  • but different cell wall (extra lipid layer) –> hard to treat
    • can also enter dormant state
    • able to treat with long ABX treatment + 72% sucess in first time cases, 52% in 2nd cases
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14
Q

Name examples of bacterial STIs

A
  • Chlamydia trachomatis infection
  • Gonorrhoea (Neisseria gonorrhoeae)
  • Syphilis (Treponema pallidum)
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15
Q

What are the characteristics of Chlamydia trachomatis?

A

Bacterioum

  • intracellular pathogen
  • most frequent STI in europe
  • In other parts of the world: eye infections
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16
Q

What are the main characteristics of Neisseria gonorrhoeae?

A

Causes STI

  • Gramm -ve bacterium
  • causes infections in Urogentical tract
  • via
    • pili and antigenic variation that halps it to escape immune detection
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17
Q

Name some examples of food and water bourne infections

A

MANY

  • Campylobacter sp. mostly C. jejuni
  • Salmonella sp.
  • Vibrio cholerae
  • Listeria monocytogenes
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18
Q

Whar are characteristics of Campylobacter sp. )mostly C. jejuni)?

A

Foodbourne disease (Uncooked poultry)

  • commonest infectious disease in EU
  • ususally only sporadic disease (no outbreak)
  • highest risk: young children
  • Virulence
    • Adhesion and Invasion factors,
    • Flagella motility,
    • Type IV Secretion system, Toxin
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19
Q

What are the characteristics of Salmonella sp?

A
  • Source: uncooked poultry
  • one of the most common GI infections in EU
  • has outbreaks
  • highest infection rate: small children
  • Virulence: Type III secretion system + toxin production
20
Q

What are the main characteristics of Listeria monocytogenes?

A
  • Intracellular pathogen: can also cross Placenta and BBB
    • immunocompromised expecially at risk (elderly, pregnant and their fetus)
21
Q

Name examples of bacterial Emerging and vector-borne diseases

A

Generally: Rare!

  • Plague (Yersinia pestis; Gram-)
  • Q fever (Coxiella burnetti; Gram –)
22
Q

Name examples of vaccine preventable bacterial infections

A
  • Diphtheria (Clostridium diphtheriae Gram +)
  • Invasive Haemophilus influenzae disease (Gram -)
  • Invasive meningococcal disease (Neisseria meningitidis Gram -)
  • Invasive pneumococcal disease (IPD)(Streptococcus pneumoniae Gram +)
  • Pertussis (Bordetella pertussis Gram -)
  • Tetanus (Clostridium tetani Gram +)
23
Q

What is an antimicrobial?

A

interferes with growth & reproduction of a ‘microbe’

24
Q

What is an antibacterial?

A

commonly used to describe agents to reduce or eliminate harmful bacteria

25
Q

What is an antibiotic?

A

Antibiotic is a type of antimicrobial

used as medicine for humans, animals

(originally referred to naturally occurring compounds)

26
Q

What is an Healthcare-associated infection (HAI)?

A

infections that occur after exposure to healthcare

  • >48h after admission to hospital
  • (Most frequent: most frequent types of HAI are surgical site infections, urinary tract infections, pneumonia, bloodstream infections and gastrointestinal infections)
27
Q

Explain why hospital patients are particularly at risk of aquiering HAI?

A
  1. Interventions done in hospital
    • provide route of infection
    • cause immunocompormisation (e.g. Chemotherapy)
  2. Dissemination
    • contact with a lot of staff + infections are common in hospital
  3. Concentration
    • many people closely next to each other
28
Q

What are the commonest Pathogens responsible for HAI?

A

ESCAPE

  • Enterococcus faecium
  • Staphylococcus aureus
  • Clostridium difficle
  • Acinetobacter baumanii
  • Pseudomonas aeruginosa
  • Enterobacteriaceae (group)
    • E.coli,
    • Klebsiella pneumoniae,
    • Enterobacter sp.
29
Q

What is one of the major problems with the ESCAPE pathogens?

A

Most of them are Antibiotic resistant and/or have ABX resistant strains

30
Q

Explain the MAO of ß-lactams

A

Type of ABX

  • Inhibit the activity of penicillin bindingproteins (PBPs) and therefore
  • Inhibit bacterial peptidoglycan synthesis
31
Q

What type of drug are Cephalosporins?

A

ß-lactams

32
Q

Explain how E.coli can develope resistance against Cephalosporins

A

Cepahlosporins= ß-lactam ABX

  • E.coli produces Extended spectrum ß-lactamase (ESBL)
  • Enzyme that cleaves and inactivated cephalosporin
33
Q

What typoe of drugs are Carbapenems?

A

Also ß-lactams

34
Q

Explain how Klebsiella pneumoniae can aquire drug resistance to Carbapenems

A

Also produce enzyme that cleaves the carbapanems

  • carbapenemase enzyme,blakpc
35
Q

Explain the role of E.coli in HAI and drug resistance

A
  • most frequent cause of UTI
  • Gram -ve
  • increase in multi-resistant strains
    • 20% resistant to Cephalosporsins
    • Normally Still sensitive to carbapenems
36
Q

Name the characteristics of Klebsiella pneumoniae

A
  • most important cause of UTI and resp infections
    • risk group: immunocompromised
  • High proportion of resistance to 3rd generation cephalosporins, fluroquinolones and aminoglycosides
37
Q

What type of Drug is Methicillin?

A

ß-lactam

38
Q

Explain how MRSA develops resistance to Methycilin

A

Expression of additional penicillin binding protein that has low affinity for Methicillin

–> can still synthsise peptidoglycans and survive

39
Q

Explain the MOA of Vancomycin

A

It inhibits cell wall synthesis by binging to PG?? precursor (and therefore inhibits PG production)

Glykopeptid-Antibiotika

40
Q

Explain how Vancomycin resistant Enterococcusfaecium (VRE) develops resistance agaisnt vancomycin

A

Vancomycin resistant Enterococcusfaecium

  • synthesissed different PG precursor so that Vancomycin has an additional substrate
  • still can do cell wall synthesis
41
Q

What are the symptoms of Hemolytic-uremic syndrome?

A

characterized by a triad of

  • acute renal failure,
  • hemolytic anemia
  • and thrombocytopenia
42
Q

What causes Hemolytic-uremic syndrome?

A

Usually caused by Shiga toxin producing E. coli (mainly in children, very rare in adults)

43
Q

Which bacteria caused the 2011 oubreak (derived from soy sporuts) in germany?

A

E. coli (EAHEC)

  • Entero-Aggregative- Haemorrhagic, Escheria Coli
44
Q

What are the characteristics of EAHEC?

A

Entero-Aggregative- Haemorrhagic, Escheria Coli

  • similar to enteroaggregative E. coli (EAEC)
    • Contains 2 plasminds
      • pAA type (contains aggregative adhesion fimbrial operon)
      • ESBL plasmid: encode for ß lactamases
    • Coding for shiga _toxin (prophage) (_EHEC)
45
Q

What is the MOA and effect of the Shiga Toxin?

A
  1. leads to inhibition of protein synthesis
    • •StxA is an enzyme that cleaves the 28S ribosomal RNA in eukaryotic cells
    • StxB= responsible pentamer for anchoring StxA to cell
  2. might affect the commensal microflora in the gut
    • bacterial ribosomes also affected

Year 2 MCD Microbiology (8 decks)

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