5.3 antibiotic resistance I

Question 1

antibiotic resistance – what is it

Answer 1

ability of bacteria to resist the effects of an antibiotic to which they were once sensitive

Question 2

drug resistant pathogen – process on how it occurs (super infection)

Answer 2

– normal microorganisms keep pathogens in check
– broad spectrum antibiotic kills all the non resistant cells, pathogen survives (resistant)
– the drug resistant pathogen will proliferate and can cause a super infection (C. difficile)

Question 3

clostridium difficle..

Answer 3

a spore former that evades antibiotics as a dormant spore, then proliferates rapidly when antibiotics have been cleared out.

Question 4

detecting antibiotic resistance test..

Answer 4

the Kirby-Bauer test

Question 5

the kirby-bauer test process

Answer 5

technician will spread a sample of patients bacteria on auger plate
– place small paper disks that has antibiotic on it.
– during incubation, antibiotic will diffuse outward, creating gradient.
– diameter of zone of inhibition tells us how sensitive bacteria is to that antibiotic.

– if small diameter – resistant
– if large diameter – sensitive to bacteria.

Question 6

Mechanisms for drug resistance – inactivation of enzymes

Answer 6

Beta lactamases are bacterial enzymes that break down b-lactam antibiotics making bacteria resistant to them

Question 7

what is supplemented with B lactam antibiotic to stop the resistance of it

Answer 7

clavulanic acid compound

Question 8

the role of clavulanic acid

Answer 8

clavulanic acid has a beta lactam ring of its own – it is an inhibitor of beta lactamases – it forms a stable compound with them leaving them unable to inactivate the beta lactam antibiotic

Question 9

mechanisms for drug resistance – block penetration

Answer 9

the outer membrane porin F (OmpF) transports sugars and antibiotics across the outer membrane of gram neg and into the periplasm
– what happens is that mutations in OmpF will reduce the number of porin channels and prevent/reduce antibiotic uptake

Question 10

mechanisms for drug resistance – efflux pump

Answer 10

span from the unner membrane of the cell all the way to outer membrane that has channel that allows for passage of molecules (antibiotics). from the bacterial cytoplasm, across outer membrane, and to the exterior of the cell.

Question 11

mechanisms for drug resistance – target modification – MRSA example

Answer 11

horizontally transferred DNA element (SCCmec) – has sequence labeled att for attachment that facilitates recombination into host genome.
– mecA encodes PBP2a – a form of PBP that does NOT interact with penicillin, meaning that cross-linking of peptidoglycan is still present, and penicillin does not affect the bacterium. – makes it resistant to penicillin