Week 10: Beta Lactams - PCNs, Cephalosporins, and Glycopeptides

Question 1

What is the MOA of the penicillins?

Answer 1

Inhibit the biosynthesis of peptidoglycan bacterial cell wall

Question 2

Penicillin V and Penicillin G Benzathine are active against what type of organisms?

Answer 2

Narrow spectrum - gram + mostly: S. pneumoniae, GABHS - bactericidal 
Pen V (oral) is best for group A beta-hemolytic strep - strep throat/pharyngitis
Pen G (IV) best for syphilis infection (T. pallidum)

Question 3

Amoxicillin and Augmentin (Amox/Clavulanic Acid) are active against what type of organisms?

Answer 3

More broad spectrum - Same gram + organisms as Pen V/Pen G but also some activity against gram - organisms - bactericidal
Amoxicillin - 1st line for AOM and sinusitis
Augmentin - 1st line fx for bites, UTI in pregnancy

Question 4

PCNs cautions/CI

Answer 4

• maculopapular rash (Amox in mono: not an allergic rx)
• Steven Johnson syndrome
• anaphylaxis

Question 5

PCNs ADRs

Answer 5

• serious allergic hx
• Rash
• GI (N/V/D)
• Fungal overgrowth/candidiasis

Question 6

Cephalosporin MOA

Answer 6

inhibit mucopeptide synthesis in the bacterial cell wall

Bactericidal

Question 7

1st Generation Cephalosporins activity/indications

Answer 7

Cefazolin (IV) and Cephalexin (PO)
- methicillin-sensitive S. aureus (MSSA) S. epidermidis, strep - E.coli
- used for skin and soft tissue infections - cellulitis
2nd line AOM, strep throat if PCN allergy

Question 8

2nd Generation Cephalosporins activity/indications

Answer 8

Cefuroxime, Cefprozil, Cefaclor

• same as 1st Gen plus H. Influenzae - broader gram - organism coverage
• Respiratory tract infections - Lyme dz - uncomp. UTI

Question 9

3rd Generation Cephalosporins activity/indications

Answer 9

Ceftriaxone, Cefdinir, Cefpodoxime, Ceftazidime (IV)

• broader indications - more gram - organisms - N. gonorrhoeae, H. flu, N. meningitidis
• good CNS penetration - meningitis, CAP, PID, respiratory tract infections - complicated UTIs (men, pregnancy, post-menopausal women)

Question 10

4th Generation Cephalosporins

Answer 10

Cefepime

• reserved for severe infections
• primarily active against gram + organisms - pseudomonas aeruginosa

Question 11

5th Generation Cephalosporins

Answer 11

Ceftaroline

• IV only and for more severe infections
• similar to 3rd generation, except also active against MRSA

Question 12

Cephalosporins ADRs

Answer 12

C. diff, hypersensitivity rx, hemolytic anemia, neutropenia, leukopenia, coagulation abnormalities

Question 13

Cephalosporins cautions/CIs

Answer 13

• hx of PCN allergy with anaphylaxis or hypersensitivity rx
• safe in pregnancy/lactation and pediatrics
  avoid ceftriaxone in neonates @ risk for hyperbilirubinemia
  The stronger the drug (5th generation is strongest; 1st generation is weakest) - the more chance of a C. Diff infection

Question 14

What drug is in the glycopeptide class?

Answer 14

Vancomycin (PO)

Question 15

Vancomycin MOA and indication

Answer 15

• inhibits cell wall synthesis by binding to the D-A1a-D-A1a protein in the cell wall
• oral is not well absorbed - stays in the GI tract
• used for C. diff. infection

Question 16

Vancomycin (oral) ADRs

Answer 16

• ototoxicity
• nephrotoxicity
• • monitoring for hearing and renal function