AntiR

Question 1

Why is resistance a global concern?

Answer 1

→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

Question 2

What are beta lactamase?

Answer 2

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

Question 3

What is methicillin?

Answer 3

→lactamase resistant penicillin

Question 4

What is MRSA?

Answer 4

→methicillin-resistant Staphylococcus aureus

Question 5

What 2 factors lead to vancomycin resistant MRSA?

Answer 5

→Co-infection

→genetic exchange

Question 6

Examples of syperbugzillas?

Answer 6

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

Question 7

What are the mechanisms of antibiotic resistance?

Answer 7

→Drug inactivation 
→Altered or new target
→Metabolic by-pass
→Efflux pump- pump drug outside of cell
→Intrinsic impermeability
→Overproduction of target- increased folic acid

Question 8

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

Answer 8

→Ribosome
→Porin mutations so antibiotic can’t get through
→PBPs – 
peptidoglycan synthesis
→DNA gyrase
→RNA polymerase
→Mcr1 & colistin

Question 9

Why can efflux pumps increase resistance?

Answer 9

→by acquisition of pumps

→mutations or over expression

Question 10

What can be overproduced as a mechanism of antibiotic resistance?

Answer 10

→precursor trimethoprim

Question 11

What are the different paths to resistance?

Answer 11

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

Question 12

What are the three types mechanisms of resistance?

Answer 12

→Natural resistance

→Genetic Mechanisms - acquired

→Non-Genetic Mechanisms (growth phases) tolerance

Question 13

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

Answer 13

→Porins

Question 14

What are the two genetic mechanisms of resistance?

Answer 14

→Chromosome-mediated

→Plasmid-mediated gene exchange

Question 15

Describe chromosome-mediated resistance

Answer 15

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

→Mutants are SELECTED; they are NOT induced

Question 16

Describe plasmid-mediated gene exchange for resistance

Answer 16

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

Question 17

Which bacteria is known to have many mutations?

Answer 17

→e.coli

Question 18

What are the mechanisms of gene transfer in bacteria?

Answer 18

→transformation
→transduction
→conjugation

Question 19

Describe bacteria transformation

Answer 19

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

Question 20

Describe bacterial transduction

Answer 20

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

Question 21

What is bacteria conjugation?

Answer 21

→one bacterium transfers genetic material to another through direct contact

Question 22

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

Answer 22

→ß-lactamase (Penicillinase)

→Alteration of the transpeptidase enzyme (PBP)

Question 23

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

Answer 23

→ß -Lactamase (Penicillinase)

→Alteration of porins

Question 24

What does penicillinase do?

Answer 24

→destroys active part of penicillin molecule

Question 25

What is augmentin/co-amoxiclav?

Answer 25

→Binds to and inactivates beta-lactamases →No anti-bacterial activity of its own

Question 26

Describe beta-lactam resistance in gram -ve

Answer 26

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

Question 27

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

Answer 27

→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

Question 28

How does vancomycin treat MRSA?

Answer 28

→inhibits availability of active site

Question 29

Describe vancomycin resistance

Answer 29

→Acquisition of van operon by transposition | →Makes D-ala-D-lactate - prevents vancomycin binding

Question 30

What are the two non-genetic mechanisms of resistance?

Answer 30

→Inaccessibility to drugs, TB lesion | → Stationary phase/vegetations and biofilms

Question 31

How can the stationary phase select for resistance?

Answer 31

→non-susceptible to inhibitors of cell wall synthesis

Question 32

Example of vegetative bacteria

Answer 32

→endocarditis

Question 33

How to prevent/overcome antibiotic resistance?

Answer 33

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

Question 34

How does combination therapy prevent antibiotic resistance?

Answer 34

→different targets | →overcome mutation rates

Question 35

How does control use prevent antibiotic resistance?

Answer 35

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

Question 36

Example of bacteria which is becoming resistant

Answer 36

→Neisseria gonorrhoeae

Question 37

What are carbapenems?

Answer 37

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

Question 38

Which type of bacteria is common in the gut?

Answer 38

→gram negative