Antimicrobial modes of resistance

Question 1

How do bacteria inactivate B lactam antibiotics?

Answer 1

Production of B lactamases - break open B lactam ring.

Question 2

What is clauvulanic acid?

Answer 2

B lactamase inhibitor

Question 3

What is tazobactam?

Answer 3

B lactamase inhibitor

Question 4

What is sulbactam?

Answer 4

B lactamase inhibitor

Question 5

How does resistance to vancomycin occur?

Answer 5

Altered target site. Change in terminal AA of peptide side chain.

D-ala-D-ala becomes D-ala-D-lactate.

Change to NH leads to the formation of 5 H bonds (instead of 4) and so a stable complex is formed and vancomycin is less effective.

Question 6

What are gram negative bacteria intrinsically resistant to vancomycin?

Answer 6

Cannot penetrate the cell membrane

Question 7

What % of gram positive bacteria are resistant to vancomycin?

Answer 7

10%

Question 8

What is AcRAB/TolC?

Answer 8

Antimicrobial multi-antibiotic resistance efflux. in e.coli.

Question 9

What type of penicillin is benzylpenicillin?

Answer 9

B lactamase sensitive

Question 10

How is benzypenicillin (Pen G) administered?

Answer 10

IV or IM

Question 11

What type of penicillin is Flucloxacillin?

Answer 11

B lactamase resistant

Question 12

What is the standard dose of benzylpenicillin?

Answer 12

1.2g fours times a day

Question 13

What is the dose of benzylpenicillin used for endocarditis?

Answer 13

2.4g every 4 hours

Question 14

What antibiotic should be used immediately if meningitis is suspected?

Answer 14

Benzylpenicillin

Question 15

What is the oral BA of amoxicillin?

Answer 15

70-90%

Question 16

What are the side effects of penicillins?

Answer 16

Hypersensitivity
Neurotoxicity
Renal failure
Diarrhoea, c.diff

Question 17

What causes c.diff?

Answer 17

Oral broad spec AB kills gut bacteria

Resistant pathogenic gut bacteria causes superinfection

Question 18

Where do we isolate Cephalosporins from?

Answer 18

Cephalosporin acremonium