Powerpoint 24

Question 1

threatens the effective prevention and treatment of an ever-increasing range of infections caused by bacteria, parasites, viruses and fungi
-present in all parts of the world. New resistance mechanisms emerge and spread globally

Answer 1

Antimicrobial resistance (AMR)

Question 2

routinely used to qualitatively determine susceptibility

• standard concentration of strain uniformly spread of standard media
• discs impregnated with specific concentration of antibiotic placed on plate and incubated

Answer 2

Kirby-Bauer disc diffusion

Question 3

clear zone of inhibitions around disc reflects

Answer 3

susceptibility

Question 4

quantitative test to determine lowest concentration of specific antimicrobial drug needed to prevent growth of specific organism

Answer 4

Minimum Inhibitory concentration (MIC)

Question 5

Some organisms produce enzymes that chemically modify drug

Answer 5

Drug inactivating enzymes

Question 6

this breaks B-lactam ring of penicillin antibiotics

Answer 6

Penicillinase

-ex/ of dug activating enzyme

Question 7

Minor structural changes in antibiotic target can prevent macrolides from binding
-changes in ribosomal RNA prevent macrolides from binding to ribosomal subunits

Answer 7

Alteration of target molecule

Question 8

Decreased uptake of the drug

-alterations in membrane proteins decrease permeability

Answer 8

Mechanisms of resistance

Question 9

some organisms produce efflux pumps

Answer 9

increased elimination of the drug

Question 10

• > enables organism to resist higher concentrations of drug

- >tetracycline resistance

Answer 10

increased elimination of the drug

Question 11

alteration of existing genes

-called vertical evolution

Answer 11

spontaneous mutation

Question 12

resistance acquired by transfer of new genes called horizontal transfer

Answer 12

acquisition of new genes

Question 13

part of normal intestinal flora, common cause of secondary infectious drug treatment

Answer 13

Enterococci

Question 14

Intrinsically resistant to many common antimicrobials

Answer 14

Enterococci

Question 15

some strains are resistant to vancomycn

-terned VRE ( vancomysin resistant enterococcus)

Answer 15

Enterococci

Question 16

Many strains achieve resistance via transfer of plasmid

Answer 16

Enterococci

Question 17

is emerging antimicrobial resistance

Answer 17

Staphylococcus areus

Question 18

in around 50 years most staphylococcus strains acquired will be resistant to

Answer 18

penicillin

-due to acquisition of penicillinase genes

Question 19

staphylococcus has to now be treated with

Answer 19

methicillin (penicillinase resistant penicillin)

-MRSA–> methicillin resistant staphylococcus aureus

Question 20

many of these strains are still susceptible to vancomycin

-now emeergins VISA- vancomysin intermediate Staphylococcus aureus and VRSA has been reported

Answer 20

MRSA

Question 21

some strains of this have now gained resistance

• resistance due to modification in genes coding for penicillin-binding proteins
• changes due to quisition of chromosomal DNA from other strains
• generally via DNA mediated transformation

Answer 21

Streptococcus pneumoniae

Question 22

organisms in active infection often resistant to one of the multiple drugs used to treat

Answer 22

Mycobacterium

tuberculosis

Question 23

when organisms become resistant to rifampin and isoniazid organisms termed multi-drug-resistant

Answer 23

Mycobacterium

tuberculosis

Question 24

MDR-TB multiple drug resistant in 2010 450 000 NEW cases of MDR-TB

Answer 24

Mycobacterium

tuberculosis

Question 25

extremely drug resistant TB

Answer 25

XDR-­‐TB