Beta Lactam Antibiotics

Question 1

Natural Penicillins

Answer 1

Penicillin VK
Penicillin G Benzathine (Bicillin L-A)

Activity:
- Streptococci
- Enterococci
- Gram - anaerobes (mouth flora)

PenG: DO NOT GIVE IV

Question 2

Antistaphylococcal Penicillins

Answer 2

Dicloxacillin
Nafcillin
Oxacillin

Activity:
- Streptococci
- Staphylococci (inc MSSA)

Notes:
- preferred for MSSA soft tissue, bone, joint, endocarditis, & bloodstream infections
- no renal adjustments
- Nafcillin is a vesicant -> extravasation treatment: cold packs & hyaluronidase injections

Question 3

Aminopenicillins

Answer 3

Amoxicillin
Ampicillin

Activity:
Streptococci
Enterococci
Gram + anaerobes (mouth flora)
Some gram -
- Haemophilus
- Neisseria
- Proteus
- E coli

Notes:
- Amoxicillin: do not use XR forms if CrCl < 30
- Ampicillin PO rarely used dt poor F
- IV ampicillin must be diluted in NS only

Question 4

Aminopenicillins + beta-lactamase inhibitor

Answer 4

Amoxicillin/Clavulanate (Augmentin)
Ampicillin/Sulbactam (Unasyn)

Activity:
Aminopenicillin activity PLUS:
- MSSA
- More resistant G- (HNPEK)
- Gram - anaerobes (B. frag)

Notes:
- Do not use Augmentin XR formulations if CrCl < 30
- IV Unasyn must be diluted in NS only

Question 5

HNPEK

Answer 5

More resistant gram negatives:
- Haemophilus
- Neisseria
- Proteus
- E coli
- Klebsiella

Question 6

Extended spectrum penicillins

Answer 6

Piperacillin/Tazobactam (Zosyn)

Activity:
Broad spectrum activity
Cover same as Amino + BLi PLUS
Other gram negatives: Citrobacter, Acinetobacter, Providencia, Enterobacter, Serratia (CAPES), and PSEUDOMONAS

Question 7

Penicillin class characteristics

Answer 7

CI:
- type 1 HSR to another beta-lactam
ADE:
- seizures (with accumulation due to incorrect dose)
- GI upset
- diarrhea
- rash (inc SJS/TEN/HSR)
- hemolytic anemia
- renal failure
Monitor:
- renal function, sx of HSR w/ 1st dose

Question 8

Penicillin DDIs

Answer 8

• Probenecid can inc levels of beta lactams (sometimes used on purpose)
• inc levels of methotrexate
• Most beta-lactams enhance anticoag effect of warfarin
• Exception: Nafcillin & Dicloxacillin inhibit the anticoag effect of warfarin

Question 9

1st gen cephalosporins

Answer 9

Cefazolin
Cephalexin (Keflex)

Activity
- Gram positive cocci (strep & staph)
- Some activity against gram negative rods (proteus, E coli, klebsiella (PEK))

Question 10

2nd gen cephalosporins

Answer 10

Cefuroxime
Cefotetan (Cefotan)
Cefoxitin

Cefuroxime:
- Staph
- More resistant strains of S pneumoniae
- HNPEK

Cefotetan, cefoxitin:
- Same as above + gram negative anaerobes (B fragilis)

Question 11

3rd gen cephalosporins

Answer 11

Cefdinir
Ceftriaxone
Cefotaxime

Ceftazidime (Fortaz, Tazicef)

Ceftriaxone, cefotaxime, cefpodoxime, cefdinir:
- Resistant strep (S pneumoniae & viridans)
- Staphylococci (MSSA)
- Gram positive anaerobes (B fragilis)
- Resistant strains of HNPEK

Ceftazidime:
- Lacks gram positive activity
Covers pseudomonas

Question 12

4th gen cephalosporins

Answer 12

Cefepime

Broad gram negative activity:
- HNPEK
- CAPES (Citrobacter, Acinetobacter, Providencia, Enterobacter, Serratia)
- Pseudomonas

Gram positive activity:
- Resistant strep (S pneumoniae & viridans)
- Staphylococci (MSSA)
- Gram positive anaerobes (B fragilis)

Question 13

5th gen cephalosporins

Answer 13

Ceftaroline fosamil (Teflaro)

Activity:
- Broad gram negative & gram positive activity
- The only cephalosporin that covers MRSA

Question 14

Cephalosporin CI

Answer 14

• Hyperbilirubinemic neonates (causes biliary sludging & kernicterus)
• concurrent use with calcium containing IV products in neonates < 28 days old

Question 15

Cephalosporin Warnings

Answer 15

Cross reactivity with penicillin allergy

Question 16

Cephalosporin ADE

Answer 16

seizures with accumulation (incorrect dosing)
GI upset
diarrhea
rash/allergic rxns/anaphylaxis
hemolytic anemia
SJS/TEN

Question 17

Cefazolin

Answer 17

1st gen cephalosporin
IV/IM

Question 18

Keflex

Answer 18

1st gen cephalosporin
Cephalexin
PO

Common uses:
- skin infections (MSSA)
- strep throat

Question 19

Cefuroxime

Answer 19

2nd gen cephalosporin
PO/IV/IM

Common uses:
- acute otitis media
- CAP

Question 20

Cefotan

Answer 20

2nd gen cephalosporin
Cefotetan
IV/IM

contains a side chain with can increase risk of bleeding & cause a disulfiram-like reaction with alcohol ingestion

Question 21

Cefoxitin

Answer 21

2nd gen cephalosporin
IV/IM

Question 22

Cefdinir

Answer 22

3rd gen cephalosporin
PO

Common uses:
- acute otitis media

Question 23

Ceftriaxone

Answer 23

3rd gen cephalosporin
IV/IM

no renal adjustment

CNS penetration with high doses (e.g. 2g Q12H)

Question 24

Cefotaxime

Answer 24

3rd gen cephalosporin
IV/IM

Question 25

Fortaz, Tazicef

Answer 25

3rd gen cephalosporin
Ceftazidime
IV/IM

Question 26

Cefepime

Answer 26

4th gen cephalosporin
IV/IM

Question 27

Teflaro

Answer 27

5th gen cephalosporin
Cetaroline fosamil
IV

Question 28

Cephalosporin DDI

Answer 28

calcium containing IV fluids -> precipitate

Cefuroxime, cefpodoxime, & cefdinir should be separated from antacids by 2 hrs

Question 29

Merrem

Answer 29

Meropenem
Class: carbapenem

Question 30

Invanz

Answer 30

Ertapenem
Class: carbapenem
commonly used for diabetic foot infections

Question 31

Carbapenem clinical characteristics

Answer 31

CI: beta lactam allergy
Warnings:
- do not use with penicillin allergy
ADE:
- diarrhea, rash/severe skin rxn, bone marrow suppression with prolonged use
- CNS effects (AMS, seizures) with larger doses or renal dysfunction
Monitor:
- renal function

Question 32

Carbapenem activity

Answer 32

Very broad spectrum, usually reserved for MDR gram negative infections
Easier to list what they don’t cover:
- atypical pathogens
- MRSA
- VRE (vanco resistant enterococci)
- C diff

Ertapenem has no activity against pseudomonas, acinetobacter, or enterococcus

Question 33

Azactam

Answer 33

Aztreonam
Class: monobactam
Can be used in pts with beta lactam allergy
Activity:
- good gram negative coverage (HNPEK, CAPES, pseudomonas)
- no gram positive or anaerobic activity