AntiR Flashcards

1
Q

Why is resistance a global concern?

A

→Increases mortality

→challenges control of infectious diseases

→threatens a return to the pre-antibiotic era

→increases the costs of health care

→jeopardizes health-care gains to society

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are beta lactamase?

A

→enzymes produced by bacteria that break open the beta-lactam ring, inactivating the beta-lactam antibiotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is methicillin?

A

→lactamase resistant penicillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is MRSA?

A

→methicillin-resistant Staphylococcus aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What 2 factors lead to vancomycin resistant MRSA?

A

→Co-infection

→genetic exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Examples of syperbugzillas?

A

→Enterococci - G+ve
→Acinetobacters- G-ve
→MRSA- G+ve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the mechanisms of antibiotic resistance?

A
→Drug inactivation 
→Altered or new target
→Metabolic by-pass
→Efflux pump- pump drug outside of cell
→Intrinsic impermeability
→Overproduction of target- increased folic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What features of protein synthesis can be a source of resistance?

A
→Ribosome
→Porin mutations so antibiotic can’t get through
→PBPs – 
peptidoglycan synthesis
→DNA gyrase
→RNA polymerase
→Mcr1 & colistin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why can efflux pumps increase resistance?

A

→by acquisition of pumps

→mutations or over expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can be overproduced as a mechanism of antibiotic resistance?

A

→precursor trimethoprim

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the different paths to resistance?

A

→Directed at antibiotic itself
→New or Altered target
→Altered transport- excess pump
→Metabolic by-pass- metabolic change D-ala-D-lac and vancomycin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the three types mechanisms of resistance?

A

→Natural resistance

→Genetic Mechanisms - acquired

→Non-Genetic Mechanisms (growth phases) tolerance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What structure in the cell wall of bacteria results in multiple resistance?

A

→Porins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two genetic mechanisms of resistance?

A

→Chromosome-mediated

→Plasmid-mediated gene exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe chromosome-mediated resistance

A

→spontaneous mutation:
→in the target molecule
→in the drug uptake system

→Mutants are SELECTED; they are NOT induced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe plasmid-mediated gene exchange for resistance

A

→Common in Gram-negative bacteria
→Transferred via conjugation
→Multidrug resistance

17
Q

Which bacteria is known to have many mutations?

A

→e.coli

18
Q

What are the mechanisms of gene transfer in bacteria?

A

→transformation
→transduction
→conjugation

19
Q

Describe bacteria transformation

A

→fragment of DNA from another bacterial cell is incorporated into bacteria chromosome

20
Q

Describe bacterial transduction

A

→DNA is transferred from one bacterium to another by a virus

21
Q

What is bacteria conjugation?

A

→one bacterium transfers genetic material to another through direct contact

22
Q

How can gram +ve bacteria be resistant to beta lactams?

A

→ß-lactamase (Penicillinase)

→Alteration of the transpeptidase enzyme (PBP)

23
Q

How can gram-ve bacteria be resistant to beta lactams?

A

→ß -Lactamase (Penicillinase)

→Alteration of porins

24
Q

What does penicillinase do?

A

→destroys active part of penicillin molecule

25
Q

What is augmentin/co-amoxiclav?

A

→Binds to and inactivates beta-lactamases

→No anti-bacterial activity of its own

26
Q

Describe beta-lactam resistance in gram -ve

A

→Porin mutates or new porin type Multi-resistant
→PBP - mutates or bacteria acquires a new PBP
→bacteria acquires a beta-lactamase enzyme

27
Q

What are the mechanisms by which bacteria become resistant to penicillin?

A

→Produce penicillinases / beta lactamases that cleave the beta lactam ring- penicillin is inactivated
→Acquire alternative forms of / or mutations in penicillin binding proteins (PBPs) - penicillin can’t bind

→Acquire alternative forms of / mutations in porins - penicillin cannot get into cell

→Acquire alternative forms of / mutations in efflux pumps -penicillins are pumped out faster

28
Q

How does vancomycin treat MRSA?

A

→inhibits availability of active site

29
Q

Describe vancomycin resistance

A

→Acquisition of van operon by transposition

→Makes D-ala-D-lactate - prevents vancomycin binding

30
Q

What are the two non-genetic mechanisms of resistance?

A

→Inaccessibility to drugs, TB lesion

→ Stationary phase/vegetations and biofilms

31
Q

How can the stationary phase select for resistance?

A

→non-susceptible to inhibitors of cell wall synthesis

32
Q

Example of vegetative bacteria

A

→endocarditis

33
Q

How to prevent/overcome antibiotic resistance?

A

→control use
→new or modified drugs
→combination therapy
→infection control

34
Q

How does combination therapy prevent antibiotic resistance?

A

→different targets

→overcome mutation rates

35
Q

How does control use prevent antibiotic resistance?

A

→not in animal feeds
→complete course [DOTS for TB]
→appropriate prescribing

36
Q

Example of bacteria which is becoming resistant

A

→Neisseria gonorrhoeae

37
Q

What are carbapenems?

A

→broad spectrum antibiotics
of last resort for Gram negative bacteria
→effective against gram negative

38
Q

Which type of bacteria is common in the gut?

A

→gram negative