Antimicrobial Resistance

Question 1

common organisms with resistance- gram ve+ and ve-

2/3 each

Answer 1

Methicillin resistant SA= MRSA
VRE= Vancomycin resistant Enterococci
ESBL-GNB= extended spectrum beta-lactamase producing GNBs
CPE- Carbepenemase producing Enterobacteriales e.g. Klebsiella
CPOs- Carbepenemase producing organisms e.g pseudomonas aeruginosa

Question 2

What does PCR-R mean

Answer 2

Pan drug resistant organisms

Low grade pathogens such as Enterococci that are resistant to all drugs

Question 3

What is XDR?

Answer 3

Extreme drug resistant organism which are more virulent such as ESBL-GNB, MRSA
Susceptible to only 2 antimicrobials

Question 4

What does MDR mean?

Answer 4

Multi drug resistant organisms that are resistant to more than 3 antimicrobials.
More organisms that are community acquired are MDR
E.g MRSA, CPEs

Question 5

Where does resistance come from?

Answer 5

Intrinsic= gene with resistance in their chromosome originally there and all genus’ have it
Acquired= through mutation or through acquisition of new genetic material

Question 6

Mechanisms of antimicrobial resistance

Answer 6

Stops activity of the AM
Stops access to the target site or removes the AM from the site
Changes the target site

Question 7

Mechanism of drug modifying enzymes

Answer 7

Beta lactamases produce an enzyme that binds to the ring and causes hydrolysis and therefore causing a destruction in activity

Question 8

Where are beta lactamases found in

Answer 8

In ESBL-GNB such as e.coli and Kleibseilla

In CPE

Question 9

Resistance via access

Answer 9

In gram negatives- where there is an outer membrane. The AM get through poring but a mutation occurs where they now have less which means that they cannot get in.
Found in fluorquinolones and beta lactams
In organisms such as Enterobacterales and Pseudomonas

Question 10

Resistance via Extrusion

Answer 10

Active extrusion via effluent pumps which usually remove secondary metabolites.
Found in macrolides and fluroquinolones
Occurs in gram pos and negs especially pseudomonas

Question 11

Resistance via changing of the target

Answer 11

Beta lactams, fluoroquinolones, aminoglycans and glyopeptides
1) via changing enzyme target
The changing of the transpeptidase enzyme needed to add a precursor the peptidoglycan cell wall leads to the beta lactam not having affinity for the target enzyme. This mutation to make PBP2 is found in MRSA
2) changing of the cell wall target
Vancomycin or glycopeptides bind on to the D-ala precursor to stop it from being added to the peptidoglycan wall. But when acquired mutation occurs, a new enzyme makes new different amino acid termite D-serine which the AM does not have an affinity and therefore resistance occurs e.g. VRE