1. Antibacterial Agents - Inhibitors Of Cell Wall Synthesis

Question 1

What’s one Synergistic combination of cell wall synthesis inhibitors

Answer 1

Penicillin + aminoglycosides

Question 2

What’s one Antagonistic combination of cell wall synthesis inhibitors

Answer 2

Penicillin + tetracycline

Question 3

Mechanisms of action of antimicrobial agents?

Answer 3

• inhibition of bacterial cell wall synthesis
• inhibition of bacterial protein synthesis
  -inhibition of nucleic synthesis
  -inhibition of folic acid synthesis

Question 4

Primary mechanisms of resistance to penicillins and cephalosporins?

Answer 4

1. Change in penicillin binding proteins +++
2. Production of Beta Lactamase enzymes
3. Change in porins

Question 5

What is the largest group of antimicrobial agents and what does it include?

Answer 5

Bacterial cell wall synthesis inhibitors
It includes:
Penicillins
Cephalosporins

Question 6

What are Beta Lactam antibiotics?

Answer 6

Penicillins
Cephalosporins

Question 7

Penicillin action mechanism

Answer 7

Bind to Penicillin Binding Protein PBP which inhibits transpeptifation reaction involved in cross linking (final step in cell wall synthesis)

Question 8

Why is the Beta-lactam ring so important ?

Answer 8

It irreversibly inhibits transpeptidase

Question 9

Hiw does bacteria resists to penicillins?

Answer 9

1. Producing beta-lactamase (penicillinase)
2. Changing the structure of penicillin cell wall targets aka PBPs
3. Preventing penicillin entry to the bacteria by changing the porin structure

Question 10

How many penicillin subgroups are there?

Answer 10

4 subgroups

Question 11

Penicilin subgroup 1 ?

Answer 11

Narrow spectrum, only works on Gram+ cocci , beta lactamase sensitive
Includes: Penicillin G and V
Spectrum: streprococci, pneumococci, meningococcii, treponema pallidum (syphilis)

Espcecially used got Streptococcus

Question 12

What is the drug of choice for syphilis ?

Answer 12

Pen G

More specifically Benzathine Pen G - repository form which has the half life of 2 weeks

Question 13

Penicillin subgroup 2

Answer 13

Aka anti staph pens
Very narrow specturm
Beta lactamase resistant
Includes: Nafcillin, methicillin, oxacillin

Question 14

What is MRSA?

Answer 14

Cross resistance to all the anti staph drugs

Question 15

What is the only Pencillin subgroup that is beta lactamase resistant?

Answer 15

Subgroup 2 Aka Anti staph pens

Question 16

How do you kill MRSA

Answer 16

With a drug that doesn’t bind to PBPs cuz the resistance here is by changing the PBPs

Question 17

Penicillin sub group 3

Answer 17

Broad spectrum
Betalactamase sensitive
Includes: amoxicillin and ampicillin
Kills: Gram+ cocci and some gram-

Question 18

What is the drug of choice for Listeria?

Answer 18

Ampicillin

Question 19

The drug of choice for Otits Media (otite moyenne)?

Answer 19

Amoxicillin
Because it’s broad enough to kill all the causative organisms

Question 20

Penicillin subgroup 4

Answer 20

Very Broad Spectrum
Aka antipseudomonal but kill a lot more bacteria i e gram+ and gram-
Beta lactamase sensitive
Include ticarcillin and piperacillin
Increased activity against gram- rods

Question 21

Penicillin coverage hack?

Answer 21

All penicillins have some gram+ coverage, then the broader their spectrum the more Gram- coverage they have

Question 22

What’s clavulanic acid?

Answer 22

Beta lactamase inhibitor

Question 23

Beta lactamase inhibitors ?

Answer 23

Aka suicide inhibitors
Clavulanic acid
Sumbactam
Taeobactam

Question 24

Synergy against pseudomonas, listeria and enteroccus?

Answer 24

Penicillin + aminoglycoside

Question 25

Penicillin renal dysfunction adjustment ?

Answer 25

Like most antibiotics, they’re eliminated via active tubular secretion
And thus renal dysfunction requires dose reduction

Question 26

Probenecid (anti-gout drug) effect on penicillins?

Answer 26

It decreases penicillin tubular secretion and thus it prolong their plasma half-life and increase serum concentrations

Question 27

2 examples of an exception of penicillin elimination in renal tubes?

Answer 27

Nafcillin & oxacillin
Eliminated largely in the bile

Question 28

2 examples of an exception of penicillin elimination in renal tubes?

Answer 28

Nafcillin & oxacillin
Eliminated largely in the bile

Question 29

Penicillins side effects?

Answer 29

• hypersensitivity (from mild rash to anaphylaxis) / should assume complete cross allerginicity between individual penicillins / eliminates the entire group of treatment plan
• GI distress i.e nausea vomitting diarrhea (NVD) especially ampicillin
• Jarisch-Herxheimer reaction involved syphylis: it’s a result of the dying organisms i.e cytokines release

Question 30

Jarisch-Herxheimer reaction involved syphylis?

Answer 30

Starts 1h after starting treatment:
Patient experience fever, muscle pain

Question 31

Cephalosporin mechanisms of action and resistance

Answer 31

Identical to penicillin as they are also B lactam molecules

Question 32

How money subgroups cephalosporin habe?

Answer 32

4 subgroups aka generations

Question 33

1st gen cephalosporins?

Answer 33

• Cefazolin, cephalexin (there are soooo many)
• if a drug has a ph in its name it’s a phirst gen cephalosporin (but some have an f)
• narrow spectrum: gram + cocci (not MRSA) , e. Cholo, klebsiella, pneumoniae and some proteus
• think abt strep and staph
• used as surgical prophylaxis
• they do NOT enter the central nervous system

Question 34

2nd gen cephalosporins?

Answer 34

• Ex: cefotetan, cefaclot, cefuroxime
• Broad spectrum: increased gram - coverage, including some anaerobes
• do not enter the CNS execpt cefuroxime
  -Mnemonic: it’s a FACt (cefaclor) that I dont want a FOXy (cefoxitin), FURy (cefuroxime) man!