Cell Wall synthesis Inhibitors

Question 1

there are 2 category drugs for cell wall synthesis inhibitors…

Answer 1

1. betalactams
2. vancomycin

Question 2

what are the betalactam drugs?

Answer 2

1. Carbapenems
2. Monobactum
3. Cephalosporins
4. Penicillin

Question 3

how does penicillin work?

Answer 3

Bind to penicillin-binding proteins (PBP’s) and inactivates transpeptidase

• prevents the cross linking of peptidoglycan chains in the bacterial cell wall,
  
  • leading to loss of cell rigidity and cell death.

Question 4

how do all betalactam drugs work?

Answer 4

all inhibit transpeptidase and prevent cross linking of peptidoglycan chains in bacterial cell wall

Question 5

how does Vancomycin work?

Answer 5

Binds to D-Ala-D-Ala terminal of peptidoglycan pentapeptide side chain, leading to inhibition of transglycosylation and prevents peptidoglycan chain elongation.

Question 6

how can bacteria resist betalactam drugs?

name a bacteria capable of using each mechanism of resistance.

Answer 6

1. Penicillinases (b-lactamases): Staph
2. Alteration of penicillin-binding proteins: MRSA
3. Reduced permeability in Gram-negative cell membrane: Pseudomonas

Question 7

name the 2 penicillin drugs, 1 is penicillinase susceptible and the other is parenteral administration, both are narrow spectrum

Answer 7

penicillinase susceptible = penicillin G

parenteral = penicillin V

Question 8

what are the penicillin drugs that are narrow spectrum and are penicillinase resistant?

Answer 8

Methicillin, Naficillin, Oxacillin, Cloxacillin, Dicloxacillin

Question 9

What are the 2 penicillin drugs that are Broad Spectrum and penicillinase susceptible?

Answer 9

1. Ampicillin
2. Amoxicillin

Question 10

what are the penicillin drugs that are extended spectrum and anti-pseudomonal?

Answer 10

Ticarcillin, Piperacillin, Azlocillin

Question 11

what are the first generation cephalosporins?

Answer 11

Cephalexin, Cefazolin

Question 12

what are the Second Generation cephalosporin drugs?

Answer 12

Cefoxitin, Cefotetan, Cefaclor, Cefamandole, Cefuroxime

Question 13

what are the 3rd generation cephalosporin drugs?

Answer 13

Ceftriaxone, Cefotaxime, Ceftriaone (IM), Ceftazidime, Ceforperazone, Cefixime (Oral)

Question 14

what are the fourth generation cephalosporins?

Answer 14

Cefipime (IV), Cefpirome

Question 15

for what bacteria do you use Penicillin G or Penicillin V?

Answer 15

Streptococci, Pneumococci, Meningococci, Treponema pallidum (Syphilis)

Question 16

for what bacteria do you use Methicillin, Naficillin, Oxacillin, Cloxacillin, Dicloxacillin?

Answer 16

Staph Aureus except in MRSA

Question 17

for what bacteria do we use Ampicillin, Amoxicillin?

Answer 17

Listeria monocytogenes (Ampicillin),

H. pylori (Amoxicillin),

Question 18

what drug is used for prophylaxis for endocarditis before major procedures like dental surgery, in patients with known valvular issues?

Answer 18

Amoxicillin

Question 19

for what do you use Extended Spectrum penicillin?

Answer 19

gram neg rods and pseudomonas

Question 20

what are 2 drugs that are penicillin G?

it is used for what?

Answer 20

procaine –> syphillis

Benzathine –> rheumatic fever prophylaxis

Question 21

how can we augment the activity or widen the spectrum of Ampicillin and Amoxicillin?

name 2 combinations

Answer 21

by using them with a beta lactamase inhibitor like clavulanic acid or sulbactum

amoxicillin + clavulanic acid = Augmentin

Ampicillin + Sulbactum

Question 22

extended spectrum or antipseudomonal penicillins can be used synergistically with what other drugs?

why?

give an example of these drugs being used together.

Answer 22

Aminoglycosides

aminoglycosides enter the cell and prevents protein synthesis; penetration into a gram negative bacteria is enhanced when used with penicillin, which will break down the cell wall allowing the aminoglycoside easier entry

Piperacillin + Gentamycin

Piperacillin + Tazobactum

Question 23

which 2nd generation cephalosporin can enter the BBB?

Answer 23

cefuroxime

Question 24

what side effects can occur with the penicillins?

Answer 24

Cross-sensitivity between:

• individual penicillins
• penicillin and cephalosporins

Question 25

if a patient has an allergy towards penicillin or cephalosporin...what drug to you substitute it for?

Answer 25

macrolide or Aztreonam

Question 26

What is a side effect that can occur with Methicillin? What is a side effect that can occur with Ampicillin? What is a side effect that can occur with Ampicillin?

Answer 26

Methicillin: interstitial nephritis Ampicillin: maculopapular rash Ampicillin: diarrhea, pseudomembranous enterocolits

Question 27

if there is a superinfection with clostridium difficile, with what do you treat it ?

Answer 27

metrodinazole

Question 28

what do you treat using 1st generation cephalosporins?

Answer 28

Proteus, E.coli, Klebsiella pneumonia,

Question 29

**which cephalosporin do you use for surgical prophylaxis?**

Answer 29

**first gen (Cefazolin)**

Question 30

what do you treat using second gen cephalosporins?

Answer 30

Haemophilus influenza, Enterobacter, Neisseria, Proteus, E. coli, Klebsiella pneumonia, Serratia

Question 31

which 2nd gen cephalosporin do you use for influenza? which 2nd gen cephalosporin do you use for bacteroides fragilis?

Answer 31

cefuroxime, cefaclor, cefamandole cefoxitin, cefotetan

Question 32

which 3rd gen cephalosporin do you use for bacterial meningitis? which 3rd gen cephalosporin do you use for bacterial Pseudomonas? which 3rd gen cephalosporin do you use for bacterial Gonorrhoea? which 3rd gen cephalosporin do you use for bacterial S. typhi?

Answer 32

Cefotaxime, Ceftriaxone Cefoperazone, Ceftazidime Ceftriaxone (parenteral), Cefixime (oral) Ceftriazone, Cefaperazone

Question 33

what are side effects that happen by using cephalosporins?

Answer 33

1. Cross-hypersensitivity between cephalosporins 2. nephrotoxicity if given with aminoglycosides 3. **dusulfiram like reactions with ethanol with: Cefamandole, Cefoperazone & Cefotetan** 4. Vitamin K deficiency

Question 34

if a patient comes in with a History of **_anaphylaxis_** when **_given penicillin_**, you should **_immediately_** think that you **_can't_** give what other drug?

Answer 34

**any cephalosporin.**

Question 35

all carbapenems have what type of resistance? name all the carbapenems

Answer 35

penicillinase resistant 1. Imipenem 2. Meropenem 3. Etrapenem 4. Doripenem

Question 36

for what do you use carbapenems?

Answer 36

use in severe life-threatening infections also, bacteroides fragilis and clostridium

Question 37

how do carbapenems work?

Answer 37

Imipenem is rapidly inactivated by renal dehydropeptidase I, combined with **cilastatin** (inhibitor of renal dehydropeptidase) to prevent hydrolysis by enzymes in the renal brush border.

Question 38

what is the side effect seen with carbapenems?

Answer 38

Seizures, GI distress,

Question 39

name the only Monobactam? **what is it used for?** **what side effect is seen with this?**

Answer 39

Aztreonam **Used in gram negative infections, especially in patients allergic to penicillins/cephalosporins** **No hypersensitivity reaction between penicillins/cephalosporins and aztreonam**

Question 40

how does vancomycin work?

Answer 40

Binds to D-Ala-D-Ala terminal of the nascent peptidoglycan pentapeptide side chain, leading to inhibition of transglycosylation and prevents peptidoglycan chain elongation.

Question 41

what is the mechanism of resistance for vancomycin?

Answer 41

Decreased affinity of vancomycin for the binding site due to the replacement of terminal D-Ala by D-Lactate.

Question 42

for what do you use vancomycin?

Answer 42

MRSA, Enterococci, C. difficile

Question 43

what is a side effects occur with vancomycin?

Answer 43

Red Man’s Syndrome: release of histamine (flushing, redness of face, hypotension). Seen in fast IV infusion. Prevented by pretreatment with antihistamines. Nephrotoxicity, Ototoxicity: can become additive if used with **aminoglycosides**