8.3

Question 1

What is the mechanism of Carbapenems?

Answer 1

Small molecules – use porins to gain access to periplasma of G-
Structure resistant to most beta-lactamases
Has broad range for PBPs from different bacteria

Question 2

How can bacteria become resistant to Carbapenems?

Answer 2

Loss of production of porins on outer membrane
Overproduction of efflux pump
Altered PBPs – do not recognize carbapenems
Produce extremely powerful beta-lactamases – able to cleave carbapenem

Question 3

What is the coverage of Carbapenems?

Answer 3

G+ (staph, strep) listeria, HEN, pseudomonas

Question 4

Why is Imapenem given with elastin?

Answer 4

imipenem alone is destroyed quickly in the kidney- to prolong activity of med, need to inhibit enzyme (here Cilastatin)

Question 5

What is the coverage of meropenem and doripenem?

Answer 5

Same as imipenem-

G+ (staph, strep) listeria, HEN, pseudomonas

Question 6

What makes ertipentm different from the rest of the Carbapenems?

Answer 6

No pseudomonas, no Acinetobacter

qDay dosing

Question 7

What are monobactams?

Answer 7

G-, fully synthetic
1 beta-lactam ring (not really a true b-lactam)
Can use with pts who have B-lactam (PCN) allergy

Question 8

What is the coverage of monobactams?

Answer 8

G-

Intermediate coverage for pseudomonas

Question 9

What are the toxicities of monobactams?

Answer 9

Relatively safe
Rash, Toxic epidermal necrolysis (rare), may induce eosinophilia
No allergic cross reactions between aztreonam and other beta-lactams okay to use in pts with PCN allergy

Question 10

What is the mechanism of Vanc?

Answer 10

Attack cell wall
Large- can’t pass through porins
NAG/NAM backbone liked by peptide side chains, last 2 AAs in the chain are Alanine- Vanc covers these 2 AAs, this keeps PBP from recognizing chains, therefor cross-linking between backbones is disrupted, damaging cell wall

Question 11

What is the coverage of glycopeptides?

Answer 11

G+: nearly all staph (and MRSA), strep, anaerobic G+ (c. diff)

Question 12

What are examples of glycopeptides?

Answer 12

Vancomycin

Telavancin

Question 13

What are SA of glycopeptides?

Answer 13

Infusion related syndrome – “Red man syndrome” = “Red neck syndrome”
Phlebitis
Ototoxicity – associate with peak level (25-50mcg/mL)
Nephrotoxicity – associate with trough level (10-20mcg/mL)

Question 14

What is the mechanism of televancin?

Answer 14

Promotes binding to bacterial cell membranes –> pore formation –> cell leakage

Question 15

What does daptomycin cover?

Answer 15

Active against G+ including MRSA and some VRE
No G- activity
Poor activity in lungs  not to treat PNA

Question 16

What is the MOA of daptomycin?

Answer 16

Lipid portion insert into baterial membrane –> form ion-conducting channel –> lysis

Question 17

What is the indications for daptomycin?

Answer 17

Only use for SSTI (skin and soft tissue infection) and bacteremia/endocarditis

Question 18

What are the SA of daptomycin?

Answer 18

Myopathy, especially at higher doses –> check CPK
Phlebitis
Rash
GI

Question 19

What is the mechanism of colistin?

Answer 19

unique; uses electrical charge to expel Ca+ and Mg+ that stabilize bacterial membrane. Once cations displaced, the membrane becomes destabilized, causing cell death.

Question 20

What does colistin cover?

Answer 20

Pseudomonas
E Coli
H flu
Klebsiella