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notes to flashcards year 2 - MCD > community acquired bacterial infections > Flashcards

community acquired bacterial infections Flashcards

1
Q

name some virulence factors

A
  • diverse secretion systems
  • flagella (for movement, attachement)
  • pili (adherence)
  • capsule (protect against phagocytosis)
  • endospores (metabolically dormant forms of bacteria)
  • biofilms (aggregates of bacteria embedded in polysaccharide matrix - antibiotic resistant)
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2
Q

what are exotoxins?

A

toxins that damage biological system

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3
Q

name some different exotoxins and what they do?

A
  • neurotoxins: act on nerves/ motor end plates e.g. tetanus
  • enterotoxins: act on GIT e.g. S. Aureus
  • pyrogenic exotoxins: stimulate release of cytokines e.g. S Pyogenes
  • tissue invasive exotoxins: enzymes that allow bacteria to tunnel through tissue e.g. S Aureus`
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4
Q

what are endotoxins?

A
  • only produced by gram -ve bacteria
  • not a protein
  • shed in steady amounts from living bacteria
  • e.g. Lipid A in LPS from gram -ve
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5
Q

when treating a pt with gram -ve infection, why can ABs make them worse?

A
  • bacteria lyses
  • releases large quantities of LPS/ endotoxins
  • septic shock
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6
Q

what is an outbreak?

A

sudden inc. in incidence of a disease in a particular place at a particular time

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7
Q

what is haemolytic-uraemic syndrome? what is it caused by?

A
  • triad of: acute renal failure, HA, thrombocytopenia
  • caused by EHEC (enterohaemorrhagic E. Coli)
  • reservoir in cattle
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8
Q

what was the outbreak in Germany a result of?

A
  • fusion of EHEC and EAHC strains to form EAHEC strain (entero-aggregative haemorrhagic E coli)
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9
Q

how can outbreaks be identified?

A
  • possible epidemic case
  • probably epidemic case
  • confirmed epidemic case
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10
Q

define possible epidemic case

A

any person that has developed symptoms and has met a lab criteria

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11
Q

define probably epidemic case

A

any person that has met the above criteria and has been in epidemic country / consumed possible contaminated food / been in close contact w/ confirmed epidemic case

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12
Q

define confirmed epidemic case

A

any person meeting criteria for possible case AND has had strain isolated

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13
Q

how can outbreaks be identified by PCR?

A
  • PCR showed that the isolate contained both aspects of EHEC and EAED
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14
Q

what does EAEC look like?

A

2 plasmids

  • pAA-type plasmids
  • ESBL plasmids
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15
Q

what does EHEC look like?

A
  • prophage

- encoding shiga toxin

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16
Q

describe the shiga toxin structure

A
  • AB5 subunit composition
  • StxA is enzymatic portion, cleaves RNA –> inhibition of protein synthesis and might affect gut commensal bacteria
  • StxB is pentamer that binds to hostt cell receptors
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17
Q

what are shiga toxins encoded on?

A
  • bacteriophages
  • contribute to horizontal gene transfer
  • can be given to other bacteria types in phages
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18
Q

what can EAEC colonise?

A

larger and small bowel

affects gut flora

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19
Q

what is the EAECs virulence factor?

A
  • aggregative adherence fimbriae (AAF)
  • AAF required for adhesion to enterocytes
  • stimulates IL-8 response
  • AAF also allows biofilm formation
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20
Q

define outbreak

A

a greater than normal inc. in incidence of a disease with a particular infection in a given period of time or place or both

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21
Q

how do you identify an outbreak?

A
  • surveillance
  • good and timely reporting systems
  • PCR
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22
Q

what are the most common communicable resp tract infections in EU?

A
  • legionnaire’s disease

- TB

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23
Q

What bacteria causes Legionnaire’s? Found?

A

legionella pneumophila

lives in amoeba in ponds/lakes/ air conditioning

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24
Q

what is the route of infection and virulence factor of Legionnaire’s?

A

RoI: inhalation of aerosols, grows in alveolar macrophages
VF: type IV secretion systems

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25
Q

what bacteria causes TB? what’s the virulence factor?

A

Mycobacterium tuberculosis

extra lipid layer, can enter a dormant state for reactivation

26
Q

what are the most common communicable STI’s in EU?

A
  • chlamydia

- gonorrhoea

27
Q

describe chlamydia

A
  • chlamydia trachomatis
  • gram -ve obligate intracellular parasite
  • causes >3% of world’s blindness
28
Q

describe gonorrhoea

A

neisseria gonorrhoeae
urogenital tract infection
infecting non-ciliated epithelial cells

29
Q

what are the virulence factors of neisseria gonorrhoeae?

A
  • pili

- antigenic variation mechanisms

30
Q

what are the most common communicable food and water borne disease in EU?

A
  • campylobacteriosis
  • salmonellosis
  • cholera
  • listeriosis
31
Q

what is campulobacteriosis? what group are at highest risk?

A
  • campylobacter sp
  • most infectious GI disease in EU
  • small children highest risk group
32
Q

what is the RoI of campylobacteriosis? VFs?

A
  • infection route via uncooked poultry does not cause outbreaks
  • VF: adhesion, invasion factors, flagella motility, T4 secretion systems, toxins
33
Q

what cause salmonellosis? who is at highest risk?

A
  • salmonella sp.
  • common GI infection from undercooked poultry
  • causes outbreaks
  • highest risk in small children
34
Q

what are the VF of salmonellosis?

A
  • T3 secretion systems encoded on pathogenicity islands
  • SPI1 for invasion
  • SPI2 for intraceullar accumulation
35
Q

what is cholera? What are the VF?

A
  • virbrio cholera
  • acute severe diarrhoeal disease
  • VF: T4 fimrbia, cholera toxin, carried on phages
36
Q

what does cholera toxin do?

A

inc. cAMP
opening of Cl- channels
expulsion of water from cells

37
Q

what causes listeriosis? what is most at risk?

A
  • listeria monocytogenes

- immunocompromised and pregnant people

38
Q

what are the VF of listeriosis?

A

actin based cell motility

39
Q

name 3 emerginf and vector borne diseases

A
  • plague: yersia pestis
  • Q fever: coxiella burnetti
  • Smallpox, A virus: eradicated
40
Q

what are 6 vaccine preventable diseases?

A
  • diptheria
  • invasive HA disease
  • invasive meningococcal disease
  • invasive pneumococcal disease
  • pertissis
  • tetanus
41
Q

define antimicrobial

A
  • interferes with growth and reproduction of a microbe

- antibiotics are antimicrobials

42
Q

define antibacterial

A

agents that reduce or eliminate harmful bacteria

43
Q

what are the stats about HAIs?

A
  • 1/18 pt
  • 3.2m a year
  • costs around an extra 1bn/ year
44
Q

what are the most frequent HAIs?

A
  • surgical site infections
  • UTIs
  • pneumonia
  • bacteraemias
  • GI infections
45
Q

what are the causes of HAIs?

A
  • intervention: catheters, intubation, prophylactic antibiotics
  • dissemination: carriers of infection from person to person
  • concentration
46
Q

what are the ESCAPE pathogens? what are they resistant to?

A
  • Enterococcus faecium: vancomycin resistant
  • S. Aureus: MRSA
  • C. Diff: infect due to previous AB treatment
  • Acinetobactor baumanii: highly drug resistant
  • Pseudomonas aerugionosa: MDR
  • Enterobacteriaceae: MDR
47
Q

What are Cephalosporins? Target pathway? Target protein?

A 
class of beta lactam antibiotics
Pathway: inhibit peptidoglycan synthesis
Protein: inhibit activity of penicillin binding proteins
48
Q

what is the resistance mech to cephalosporins?

A
  • Extended spectrum beta-lactamase (ESBL)

- ESBL enzyme cleaves cephalosporin

49
Q

what are carbapenems?

A

same as cephalosporins

50
Q

what is the mech of resistance to carbapenems?

A
  • carbapenemase enzyme encoded on mobile genetic element

- enzyme cleaves carbapenem

51
Q

what is the most frequent cause of community and HAI UTIs?

A

pathogenic E coli

52
Q

what is the most frequent cause of bacteraemia by a gram -ve bacteria?

A

pathogenic E coli

53
Q

what are the resistances in pathogenic E coli?

A
  • 3rd gen cephalosporin resistance
  • most resistance mediated by ESBLs
  • still sensitive to carbapenems
54
Q

what are the causes and risk groups for Klebiella pneumoniae?

A
  • causes: UTIs and resp tract infection

- risk groups: immunocompromised

55
Q

what are the resistances in Kelbiella pneumoniae?

A
  • 3rd gen cephalosporins, fluoroquinolones and aminoglycosides
  • CRKP: Carbapenem-Resistant pneumoniae
56
Q

what are the people at risk for pseudomonas aeruginosa?

A

immunocompromised

57
Q

what is methicillin? Target pathway? Target proteins?

A
  • beta-lactam antibodies
  • pathway: inhibit peptidoglycan synthesis
  • protein: inhibit activity of penicillin binding proteins
58
Q

what is the mech of methicillin resistance?

A
  • expression of additional penicillin binding protein
  • PBP2A has low affinity for methicillin, can still function in presence of antibiotic
  • MRSA strians can synthesise peptidoglycan and can survive in presence of methicillin
59
Q

what is the target pathway and target of Vancomycin?

A

Pathway: inhibit PG synthesis
Target: binds to PG precursor

60
Q

what is the mech of vancomycin?

A
  • multiple protein genes encoded on plasmid or transpoon

- results in synthesis of different PG precursor

61
Q

what is VRE?

A

3rd most frequently identified cause of nosocomial blood stream infections

62
Q

what is the resistance pathway of VRE?

A
  • vancomycin resistance around 60%

- VRE synthesises a different peptidoglycan precursor that is not targeted by vancomycin

notes to flashcards year 2 - MCD (24 decks)

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