Cushman lecture 17

Question 1

Penicillin G (benzylpenicillin)

Answer 1

Spectrum:gram(+)cocci
B-lactamasesensitivity:Yes Administration:parenteral (High nucleophilicity, unstable in acidic conditions)
o Toxicity: acute allergic reactions
Precautions:caution with hx of asthma or significant allergies

Question 2

Phenoxymethyl Penicillin (Penicillin V)
Use, administration, toxicity, and is it beta lactamase sensitive

Answer 2

Spectrum: gram (+) cocci
B-lactamase sensitivity: Yes
Administration: oral
Electronegative – O – lowers nucleophilicity, stable in acidic conditions
Toxicity: acute allergic reactions
Precautions: caution with hx of asthma or significant allergies

Question 3

Methicillin
Use, administration, and is it beta lactamase sensitive

Answer 3

Spectrum: S. aureus, DISCONTINUED
B-lactamase sensitivity: No (resistant)
-Due to steric hindrance of nucleophilic attack by enzyme on B-lactam carbonyl
Administration: parenteral
-High nucleophilicity due to - OCH3 groups that form formal resonance structure, unstable in acidic conditions
Precaution: Methicillin-Resistant Staphylococcus aureus (MRSA)
-MRSA is resistant to methicillin due to a mutation in a penicillin-binding protein
(transpeptidase) à mecA (PBP2A)

Question 4

Nafcillin
beta lactamase sensitive?

Answer 4

Spectrum: gram (+) cocci
B-lactamase sensitivity: No (resistant)
-Due to steric hindrance of nucleophilic attack by enzyme on B-lactam carbonyl Administration: parenteral
-Slightly more stable in acid than methicillin
-High nucleophilicity due to – OCH2CH3 group, unstable in acidic conditions

Question 5

Beta lactamase resistant Oral penicillins

Answer 5

Oxacillin, Cloxacillin, and Docloxacillin
These are beta lactamase resistant
Gram positive Cocci
Oxacillin and Cloxacillin have been discontinued for oral use but Dicloxacillin is still available for oral use and Oxacillin is available for injection use only

Question 6

Ampicillin
Use, administration, and is it beta lactamase sensitive

Answer 6

This is a broad spectrum antibiotic that can be used for many gram - bacteria (Salmonella, shegella,Proteus, mirabilis, E. Coli, Haemophilis, and neisseria)

Orally administered and Beta lactamase sensitive

Question 7

Amoxicillin

Answer 7

Better oral absorption than ampicillin
Beta lactamase sensitive

Question 8

Potassium Clavulanate + Amoxicillin

Answer 8

Augmentin

B lactamase inhibitor and a b lactamase sensitive drug to enhance activity of the antibiotic

Question 9

Sulbactam + ampicillin

Answer 9

Unasyn

Question 10

Tazobactam + Pipericillin

Answer 10

Zosyn

Question 11

Avibactam + Ceftazidime

Answer 11

Avycaz
Cephalosporin

Question 12

Acylureidopenicillin (Piperacillin)

Answer 12

Broad spectrum Parenteral Penicillin
Activity against gram + bacteria and some Gram - bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae, bacteroides fragilis)

Question 13

Penicillins MOA

Answer 13

React with transpeptidases to inhibit the peptidoglycan cross linking

Question 14

Cephalosporins MOA

Answer 14

React with transpeptidase to inhibit the peptidoglycan cross linking

Question 15

Allergenicity Cephalosporins

Answer 15

Patients who are allergic to penicillins should use caution when using cephalosporins as well althought allergic responses are much lower risk with cephalosporins

Question 16

Cefazolin

Answer 16

First generation Cephalosporin
Parenteral agent

Active against Gram + cocci (staphylococcus aureus and staphylococcus Pyogenes, Streptococcus agalactiae, and streptococcus pneumoniae)

Question 17

Cephalexin

Answer 17

First generation Cephalosporin
Orally taken

Active against Gram + cocci (staphylococcus aureus and staphylococcus Pyogenes, Streptococcus agalactiae, and streptococcus pneumoniae)

Have unreactive side chain at C-3 (methyl group)

Question 18

First generation Cephalosporins

Answer 18

Cephalexin and Cefazolin

Question 19

Cefuroxime

Answer 19

Second Generation Cephalosporins
Parenteral and oral agent

Have gram + activity as the first generation and Haemophilus influenzae as well and also activity against some gram - bacteria including Acinetobacter, Citrobacter, Enterobacter, E. Coli, Klebsiella, Neisseria, Proteus, Providencia, and Serratia

Must be protected from light

Question 20

Ceftazidime

Answer 20

Third generation Cephalosporins
Parenterally active

Less active against staphylococci than the first and second generation but much more active vs Gram - bacteria

Frequently used for hospital acquired multidrug resistant strains

Question 21

Cefixime

Answer 21

Third generation Cephalosporin
Orally active

Less active against staphylococci than the first and second generation but much more active vs Gram - bacteria

Question 22

Cefepime

Answer 22

Fourth generation Cephalosporin
Parenterally active

Retain antibacterial spectrum of the third generation cephalosporins as well as Pseudomonas aeruginosa and some enterobacteria that are resistant to third generation. They also have more activity against gram + organisms

Has a methoximino group at C-7 which stabilizes it against Beta- lactamse

Question 23

Ceftaroline fosamil

Answer 23

Fifth generation Cephalosporin
Ceftaroline fosamil is a pro drug that becomes Ceftaroline after IV infusion

Broad spectrum antibiotic active against MRSA and used for MRSA and Community acquired bacterial Pneumonia

It inhibits MRSA PBP2a