Beta Lactams

Question 1

Important Gram (+) bacteria to know…

Answer 1

S. Aureus MSSA and MRSA

S. Pneumoniae

C. Diff (also an anaerobe)

Question 2

Important Gram (-) bacteria to know….

Answer 2

P. aeruginosa

B. Fragilis (also an anaerobe)

Question 3

Important Atypical bacteria to know…

Answer 3

Legionella sp

Mycoplasma pneumoniae

Chlamydia sp

Question 4

List all the general classes of B Lactams Abx ( 4 total)

Answer 4

1. Penicillin PNC
2. Cephalosporins
3. Monobactam
4. Carbapenems

Question 5

MOA of Beta Lactams???

PK/PD parameter???

Answer 5

MOA: bactericidal; irreversibly forms a covalent bond with the PBP (transpeptidases) which prevents the building of the PG wall

PK/PD parameter? TIME>MIC

Question 6

There are five (but we only need to know 4) generations/classes of penicillin with differences in stability and coverage… General

Answer 6

1. Natural penicillins - Penicillin G (peritoneal) & V (oral)
2. Aminopenicillins- Ampicillin, amoxicillin
3. Anti‐staphylococcal penicillins- Nafcillin, Methicillin, Oxacillin, Dicloxacillin
4. Ureidopenicillins- Piperacillin used with tazobactam (Combo brand name Zosyn®),

Question 7

PNC

Coverage of Natural PNC

Answer 7

Natural penicillin, PCN V, remains the primary treatment for SYPHILIS ( caused by Treponema pallidum)

cover against Streptococcus pneumoniae and treat CAP

Question 8

PNC

Key points of Aminopenicillins

Answer 8

Designed to increase penetration of the Gram (–)outer membrane

Ampicillin (IV; PO,) Probenicid used to slow excretion by kidney.

Amoxicillin (PO, better absorbed than ampicillin)

Aminopenicillins are used with β -lactamase inhibitors (clavulanate, sulbactam) to
prevent hydrolysis by β-lactamases

Question 9

PNC

Coverage of Aminopenicillins (with and without Beta lactamases inhibitor)

Answer 9

AminoPNC alone covers: S. Pneumonia

COMBO: MSSA, S. Pneumonia, B. Fragilis

Question 10

PCN

Anti-staphylococcal PCNs key points + coverage

Answer 10

Designed to be resistant to staphylococcal β-lactamases!!!

Covers: MSSA and S.Pneumonia

Question 11

PCN

Anti-staphylococcal PCN - NAFCILLIN

Answer 11

Nafcillin: Main route is IV, highly-protein bound so
lowers concentration free in serum.
Biliary excretion!!!!
Associated with neutropenia

Question 12

PCN

Ureidopenicillins - Key points and coverage

Answer 12

They are the anti-pseudomonal PCNs!

Piperacillin: available as a single agent (anti-Pseudomonal) but almost
always used as a piperacillin-tazobactam (Zosyn®) combination to
extend activity against β-lactamase-producing bacteria.

Coverage: MSSA
S. pneumonia
B. Fragilis
P. aeruginosa

Question 13

Moving on to the next Beta Lactam…

Cephalosporins!! general info?

Answer 13

most widely prescribed and largest-selling class of the β-lactam antibiotics!

1. MOA same as PCNs
2. PK/PD parameter for efficacy? T>MIC
3. increased β‐lactamase resistance
4. Water soluble & stable to pH.
5. Useful alternatives in patients who are intolerant to penicillins (1‐3% cross‐
   hypersensitivity) .
6. Classified as 1st to 5th generation.

Question 14

Beta Lactam

1st Gen Cephalosporins
Drugs + coverage

Answer 14

Drugs: Cefazolin, Cephalexin

Covers: MSSA, S. pneumonia

DONT CROSS BBB

Question 15

Beta Lactam

2nd Gen Cephalosporins
Drugs + coverage

Answer 15

Drugs: Cefoxitin, Cefotetan

Covers: MSSA, S. Pneumonia, B. Fragilis!!

Question 16

Beta Lactam

3rd Gen Cephalosporins
Drugs + coverage

Answer 16

Drug and coverage:

Cefotaxime and Ceftriaxone (choice for S.P) –> MSSA, S.pneumonia
Ceftazidime (use with avibactam) –> P. aeruginosa

Question 17

Beta Lactam

4th Gen Cephalosporins
Drugs + coverage

Answer 17

Drug: Cefepime

Covers: MSSA, S. pneumonia, P. aeruginosa

Question 18

Beta Lactam

5th Gen Cephalosporins
Drugs + coverage

Answer 18

Only β-lactam (only cephalosporin of 1st-5th) that covers MRSA is
CEFTAROLINE (Teflaro®)!!!

THIS IS THE ONLY B LACTAM TO COVER MRSA

Also covers: MSSA, S.pneumonia

Question 19

Moving on the the next B Lactam!!

Monobactams (Aztreonam) general and coverage

Answer 19

were expected to be resistant to β-lactamases.. BUT Aztreonam is inactivated by ESBLs!

Aztreonam is a good alternative for patients who are allergic to PCN.

Coverage: P.aeruginosa

Inactive against Gram (+) bacteria and anaerobes (does not bind to their PBPs‐
binds only to PBP3)

Question 20

Moving on the the next B Lactam!!

Carbapenems! drugs + coverage

Answer 20

are the broadest-spectrum β-lactam antibiotics

Imipenem/cilastatin (Primaxin IV®), Meropenem
Doripenem, Ertapenem (Invanz®)

All carbapenems, particularly imipenem, have been associated with SEIZURES.

Covers: MSSA, S, pneumonia, B. Fragilis, P. aeruginosa (not for ertapenem tho)