Antibiotics

Question 1

What are the antibiotics that work by cell wall synthesis inhibition?

Answer 1

Beta-lactams
- penicillins
- cephalosporins
- carbapenums
- monobactams
Glycopeptides
- vancomycin
- teicoplanin

Question 2

What antibiotics act by inhibiting protein synthesis through the 30s ribosomal sub unit?

Answer 2

Amino glycosides

Tetracyclines

Question 3

What antibiotics act by inhibiting the 50s ribosomal sub-unit?

Answer 3

Chloramphenicol
Clindamycin
Macrolides
Fusidic acid

Question 4

What antibiotics act by blocking folic acid synthesis?

Answer 4

Trimethoprim

Sulphonamides

Question 5

What antibiotics act by inhibiting nuclei acid synthesis by DNA gyrase inhibition?

Answer 5

Fluroquinolones

- cirofloxacin, norfloxacin

Question 6

What antibiotics inhibit nucleoside acid synthesis through RNA polymerase inhibition?

Answer 6

Rifamycin

- rifampicin

Question 7

What are inhibitors of cell membrane function?

Answer 7

Colistin
Polyene anti fungal drugs
- amphotericin B, nystatin

Question 8

What are the four mechanisms of antibiotic resistance?

Answer 8

1. Antibiotic inactivation through inactivating enzymes
2. Alteration AF antibiotic target sites
3. Decreased antibiotic permeability of the cell wall preventing drug access to target
4. Active antibiotic eflux from bacteria

Question 9

What are some examples of inactivating enzymes?

Answer 9

B-lactamases

Amino glycoside modifying enzymes

Question 10

What are some inhibitors of beta-lactamases?

Answer 10

Clavulanic acid
Tazobactam
Sulbactam

Question 11

What are the antibiotics that exhibit inducible chromosomal mediated beta-lactamase production?

Answer 11

Enterobacter
Serratia
Citrobacter
Acinetobacter
Pseudomonas
Proteus vulgaris
Morganella morganii

Question 12

What are the two main types of b-lactamase?

Answer 12

ESBL - extended spectrum B lactamases which have enzymes encoded by a plasmid which can be passed between bacteria
Inducible chromosomal mediated b lactamase production from escappm

Question 13

What are the usual organisms that harbour ESBLs?

Answer 13

E.coli

Klebsiella pneumoniae

Question 14

What antibiotics do ESBLs inactivate?

Answer 14

All cephalosporins

Question 15

What antibiotics do the ESCAPPM group inactivate?

Answer 15

3rd generation cephalosporins

Question 16

What is the mechanism of resistance of MRSA?

Answer 16

Alteration in penicillin binding proteins (PBP target site) meaning methicillin cannot bind and act on the bacteria

Question 17

What is the concern with use of Rifampicin alone?

Answer 17

Rapid development of resistance due to single step mutations that reduce the affinity of rifampicin for the RNA polymerase

Question 18

What is the difference in cell wall structure between gram positive and gram negatives?

Answer 18

Gram positive
- simple cell wall structure that drugs can easily penetrate
Gram negative
- more complex cell envelope that requires drugs to travel through porins

Question 19

What are some examples of penicillin/b-lactamase inhibitor combinations?

Answer 19

Amoxicillin + clavulanate
Ticarcillin + clavulanate
Piperacillin + tazobactam (tazocin)

Question 20

What are some examples of first generation cephalosporins?

Answer 20

Cephazolin
Cephalexin
Cephalothin

Question 21

What are some second generation cephalosporins?

Answer 21

Cefaclor

Cefuroxime

Question 22

What are some third generation cephalosporins?

Answer 22

Cefotaxime
Ceftriaxone
Ceftazidime

Question 23

What is a fourth generation cephalosporin?

Answer 23

Cefepime

Question 24

What carbapenem does not have action against pseudomonas?

Answer 24

Ertapenem

Question 25

What is the mechanism of Vancomycin resistance in enterococci?

Answer 25

Van A, B and C genetic mutations which prevent binding of vancomycin to cell wall components

Question 26

What is are some differences between Van A , B and C?

Answer 26

A - also resistant to Teicoplanin (another glycopeptide), can be transferred between strains B - transferred between strains C - not able to be transferred between strains

Question 27

Types of enterococcus and resistance?

Answer 27

All enterococci are instrinsically resistant to cephalosporins ``` Faecium = more resistant Faecalis = less resistant ``` Faecium is often resistant to amoxicillin and occasionally to Vancomycin Faecalis is usually sensitive to amoxicillin

Question 28

What drugs work via time above MIC?

Answer 28

B-lactams Clindamycin Macrolides Linezolid

Question 29

What drugs work via peak concentration above MIC?

Answer 29

Aminoglycasides - ie gentamicin

Question 30

What drugs work as a AUC dependant killing?

Answer 30

Vancomycin | Fluroquinolones

Question 31

What are examples of carbapenemases?

Answer 31

New Dehli metalloproteinase | Klebsiella pneumoniae carbapenemase

Question 32

What are carbapenemases resistant to and how do you treat them?

Answer 32

Resistant to all B lactams | Treat with Colistin

Question 33

What is a risk factor for development of Vancomycin resistant enterococci?

Answer 33

Use of anerobic cover - ie metronidazole | VRE genes are initally in anaerobes which are then killed and the enterococci takes up the genes and becomes VR

Question 34

What drugs provide anaerobic cover?

Answer 34

``` Metronidazole Augmentin/Tazocin (B-lactamases) Clindamycin Meropenum Chloramphenicol ```