test 6 cell wall inhibitors

Question 1

Cell Wall Inhibitors: Penicillins & Cephalosporins

Answer 1

› β- lactam antibiotics
› Selectively interfere with the synthesis of the bacterial cell wall
– Prevent peptidoglycan cross-linking in presence of antibiotics
– Newly produced cell walls are weak and the bacteria fall apart
› Require actively proliferating microorganisms
› Bactericidal

Question 2

β- lactam antibiotics Classified by

Answer 2

– Spectrum of activity (what they are able to target or not)
› Penicillin spectrum determined by “R group” attachment
– Resistance to β-lactamase
› An enzyme produced by bacteria that attacks the β- lactam ring
β- lactamase is a significant source of antibiotic resistance among microbes

Question 3

Penicillins

Answer 3

• interfere with the cross-linking
• bactericidal
  › Derived from Penicillium mold
  › First generation penicillins are effective against gram-positive and gram-negative organisms
• most widely effective and least toxic of all the antibiotics
  – BUT, resistance levels are high!
  - so use is becoming limited

Question 4

Penicillin Categories

Answer 4

1. Natural
2. Antistaphylococcal
3. Broad spectrum
4. Antipseudomonal

Question 5

Natural Penicillins

Answer 5

› Penicillin G

Question 6

Penicillin G uses

Answer 6

• pneumococcal pneumonia
  - bacterial pneumonia
• gonorrhea
• syphilis

Question 7

Antistaphylococcal Penicillins

Answer 7

› Developed in response to growing resistance to staph
› Used specifically for penicillinase-producing staphylococci (including MSSA)
› Minimal activity against gram-negative infections

Question 8

Staphylococcus Aureus

Answer 8

› Gram-positive
› Non-pathogenic & pathogenic strains
- hospital inquired infection
- Non-pathogenic
› Skin, Nostrils, Female reproductive tract
- Pathogenic
› Pimples, Impetigo, Boils, Cellulites, Abscesses, Pneumonia, Meningitis, Endocarditis, Sepsis

Question 9

Broad Spectrum Penicillins

Answer 9

› Spectrum similar to Penicillin G, but more effective against gram-negative bacilli
› Resistance now a major clinical problem
› Ampicillin
› Amoxicillin
– D.O.C for dental prophylaxis to prevent bacterial endocarditis

Question 10

Pseudomonas aeruginosa

Answer 10

– Very problematic
– Very pathogenic
– Gram negative
– Readily develops resistance to antibiotics
– Notorious for causing blue/green pus

Question 11

Antipseudomonal Penicillins

Answer 11

› Treates Pseudomonas aeruginosa
› Also effective against other gram negative bacilli
› Parenteral only (not effective orally)
› Piperacillin (most potent)
› Ticarcillin

Question 12

Clavulanic Acid

Answer 12

› Also has a β-lactam ring but no antimicrobial activity
› Suicide inhibitor of bacterial β-lactamase
– Attaches to and permanently deactivates the enzyme by letting it attack it instead of the antibiotic
› Used in combination with
– amoxicillin (Augmentin)
– ticarcillin (Timentin)

Question 13

Penicillin Pharmacokinetics

Answer 13

› Administration
– Varies-oral, IV, IM
› Absorption
– Incompletely absorbed after oral administration
› Reach intestines and affect intestinal flora= diarrhea!
– Food increases gastric emptying time and acids destroy drug
– Take on empty stomach
› Distribution
– Do not penetrate bone or BBB unless inflamed!
› Excretion
– Kidneys

Question 14

Penicillin Adverse Reactions

Answer 14

› Hypersensitivity
– 5% of patients
– Range from rash to mouth swelling to anaphylaxis
– Patient history regarding severity of previous rxn is essential
– Cross-allergies occur among β-lactams
› Diarrhea
› Nephritis
› Neurotoxicity
› Hematologic toxicities

Question 15

Cephalosporins

Answer 15

› β-lactam antibiotics
› More resistant to certain β-lactamases than penicillins
› Classified based on their resistance to β- lactamases and their spectrum
        – 1st Generation
        – 2nd Generation
        – 3rd Generation
        – 4th Generation
        – Advanced Generation
-VERY COMMONLY USED IN THE CPB PRIME

Question 16

1st Generation Cephalosporins

Answer 16

› Act as substitutes for Penicillin G
› Less expensive than later generations
› Cover MSSA
› Staph is a large open-heart infection culprit
– No advantage found using more expensive later generation cephalosporins for ECC prophylaxis

Question 17

› Cefazolin (Kefzol, Ancef)

Answer 17

- 1st Generation Cephalosporins
› Only parenteral first generation
› Dosage
        – Fixed amount in prime (1 gram) OR
        – Weight based (50mg/kg, e.g.)
› Cleared by kidneys
› Half life: 1.8 hours
› Cross sensitivity with penicillin is possible
        › CHECK THE CHART!!

Question 18

2nd Generation Cephalosporins

Answer 18

› Broader spectrum of activity

› Only cephalosporins with appreciable activity against gram-negative anaerobic bacteria

Question 19

2nd Generation Cephalosporins drugs

Answer 19

› Cefoxitin (Mefoxin)
› Cefotetan
› Cefuroxime (Ceftin)

Question 20

Cell Wall Inhibitors: Vancomycin

Answer 20

› Prevents peptidoglycan polymerization in the bacterial cell wall so they “fall apart”
› Limited to GRAM POSITIVE microorganisms
› IV
– Use restricted to MRSA, MRSE and patients with severe allergy to β-lactam antibiotics
– Prophylactically for heart valves and devices
› Oral
– Not absorbed so only for C. difficile colitis
› Renal excretion
› OVERUSE AND MISUSE HAS LEAD TO THE DEVELOPMENT OF RESISTANCE

Question 21

What is C. difficile colitis?

Answer 21

› Clostridium difficile colitis
› Bacteria that cause swelling and irritation of large intestine or colon
– Diarrhea
– Fever
– Abdominal cramps
› Caused by antibiotics killing the “good” bacteria
› Highly contagious person to person

Question 22

Vancomycin common side effects

Answer 22

• fever
• chills
• flushing
• phhlebitis