Antibiotic Stewardship

Question 1

What is an antibiotic?

Answer 1

a drug that kills or inhibits growth of microorganisms

Question 2

What is resistant?

Answer 2

somewhat arbirtray designation that implies that an antimicrobial will not inhibit bacterial growth at clinically achievable concentrations

Question 3

What is susceptible?

Answer 3

some what arbitratry designation that implies that an antimicrobial will inhibit bacterial growth at clinically acheivable concentrations.

Question 4

What is MIC?

Answer 4

the minimal inhibitory concentration; the lowest concentration of antimicrobial that inhibits growth of bacterial- commonly used in clinicla labs

Question 5

What is MBC?

Answer 5

the minimal bacterial concentration; the concnetration of an antimicrobial that kills bacteria. Used clinically only in special circumstances

Question 6

What is the breakpoint?

Answer 6

the MIC that is used to designate b/n susceptible and resitance (evidance based set by a committee)

Question 7

What are susceptibility testing methods?

Answer 7

1) MIC
2) Kirby-Bauer Disk diffusion
3) Agar dilution
4) E-test

Question 8

What is the MIC test?

Answer 8

• dilute antibiotic 2x across solution and when hit a [] that prevents growth
• wells plate for MIC testing (microfilter plate)
• many labs use automated testing and scans determine forma a specific isolate

Question 9

What it sth Kirby-Bauer Disk Difussion?

Answer 9

• looking at zone of inhibition
• can’t determine MIC directly
• have to compare versus a chart to see if susceptible versus resistent due to [] levels at site of action

Question 10

What is Agar dilution?

Answer 10

Broth dilution in an augar form

Question 11

what is the E-test?

Answer 11

-strip with a grandinet of [antibiotic] to inhibit growth of bacteria until [] is too low then IC at the pt. on the strip

Question 12

When is a fungi resistant?

Answer 12

When MIC>BP
(just becaseu less to use does not mean it is better b/c BP may be lower; adn if BP is signigicantly higher than MIC then the more susceptible
-expamle ciprofloxacin MIC = 2 and BP=2 so resistance
Piplfazo MIC=8; BP=32-64

Question 13

What are factros that lead to resistance?

Answer 13

ANTIBIOTIC USE!!!!
using antibiotics on foot and animals and when food is not process porperly they are carry ing bacterial and pass onto us

Question 14

what are the 8 reasons for over use?

Answer 14

Pts: 1) want clear explanation
2) Green nasal discharge
3) need to return to work
Physicans concerns
4) pts. expect antibiotics
5) diagnosic uncertianty
6) time pressure

Question 15

What are teh highest risk pts?

Answer 15

immunocompromized pts
hospitalized pts
invasive devices (central venous catheters)
use on one pts can cause spread to other patient

Question 16

what the four mechanisms fo resistance?

Answer 16

1) antibiotic degrading enzymes
2) decrease permiability
3) efflux pumps
4) target alterations

Question 17

Look at figure for cycle of antibiotic resistance acquisiton

Answer 17

selection ofr 1 drug casues resistance to multiple durgs due to linkage (X,Y,Z)

Question 18

What is b-lactamase?

Answer 18

confer resistance to some, many or all b-lactams antibiotics

• can be on a plasmid
• more potent in gram - bacteria
• benifical for bacteria becasue they are just increasing what they normally are doing

Question 19

what are b-lactamases more potentent on gram -?

Answer 19

located in the periplasmic space so increased in [] wherease in gram + located outside of the cell wall

Question 20

What are extended specturm B-lactamases?

Answer 20

B-lactamases that are capable of hydorlysing extened spectrum cephalosporins, penicillins adn aztronam

• usually plasma mediated
• aminoglycoside, ciprofloxacin, and trimethoprim-sulfamethoxazole resistance often encoded on same plasmid

Question 21

what are class A carbapenemases?

Answer 21

enzymes that degrade carbaphenes

Question 22

what ocurs to get decreased permeability?

Answer 22

tightens walls so drugs cant get across

-can be an innate or an aquired resistance

Question 23

why are gram - resistant to vancomyosin?

Answer 23

b/c vancomyocin is to large to get across their 2 membranes

Question 24

what are teh mechanisms of antibiotic resistance?

Answer 24

1) antibiotic degraadin enzymes
2) decreased permeability
3) efflux pumps
4) target alterations

Question 25

how are bacteria becoming resistant to vancomyocin?

Answer 25

gram + are changing their D-Ala-D-Ala sequence to D-Ala-D-Lactate

Question 26

what is conjugation?

Answer 26

plasmid transfer via contact

Question 27

What is transduction?

Answer 27

tranfer by viral delivery

Question 28

Waht is transformation?

Answer 28

transfer of free DNA

Question 29

Waht are teh adverse drug events (DEs)

Answer 29

• hypersensitivity/ allergy
• drug side effect (many pts have to be hospitalized due to this)
• clostridum difficle infection
• increasing health costs

Question 30

What are the 9 factors to concider when selecting an antibiotic?

Answer 30

1) specturm of coverage
2) patterns of resistance
3) evidence or track record for specified infection
4) achievable serum, tissue or body fluid concnetration
5) allergy (PMHx)
6) Toxicity
7) formutation (IV vs PO)
8) Adherence/Convienience (2x/day or 6x/day)
9) COST!!!

Question 31

What are the emperic therapy prinipals?

Answer 31

85%

• infection onot well defined (best guess)
• broad spectur
• multiple drugs
• evidance ususally only 2 reandomize controled trials
• more adverse rnx
• more expensive

Question 32

Waht are the directed therapy priniples?

Answer 32

15%

• infection well defiened
• narrow spectrum
• one, seldom 2 drugs
• evidance usually stronger
• less adverse rxns
• less expensive

Question 33

What does a negative culture mean?

Answer 33

does not eman it is not a bacterial infection!!! could just mean thatye they have already been txed so supression of the infection

Question 34

what is the genral trend in teh antibiotic industry?

Answer 34

a general trend V in production of antibiotics; less funding; expensive to make; hard to get physicains to perscribe new drugs

Question 35

What are the 3 principal reasons of antibiotic market failure>

Answer 35

1) Scientific
2) Economic
3) Regulation (FDA)- no more likely to die of any thing with in 28 day of tx; trial have to be largers

Question 36

What is the Gain act of 10/1/2012?

Answer 36

• provides exclusivity for antibiotis adn earmarks them for priority review
• must be approved based ont eh bugs they kill regardless of the site of infection!
• pressure to limit adverse effects

Question 37

what are the goals of antibiotic use?

Answer 37

• prevention or cure of infection w/a minimum of toxicity to pt.
• minimum impact on the pt’s microbial flora (collateral damage)
• minimum impaction on teh microbial flora of other pts/enviorment (colonization pressure, corss-infection – forgetting to wash hands)

Question 38

What sould a Dr. be aware of when reatreating a pt with in 1 yr?

Answer 38

they should use a new class of antibiotics, becasue of cross resistance

Question 39

what are teh possible reasons for a high moretality in MRSA bacteriemia?

Answer 39

• delay in effectiv therapy
• differnt pat. population
• higher virulence of isolates
• lower efficacy of vancomycin for MRSA than b-lactams for MSSA

Question 40

what is collateral damage with regarud to antibiotics?

Answer 40

a term used to refer to ecological adverse effects of antibiotic therabpy, namely the selection of drug-resistant organisms and the unwanted development of colonization or infected mulitdrug resistant organisms
-commonly linked to 2 organisms (cephalosproins, Quinolones)