69. Penicillins, Cefalosporins

Front 1

Mechanism of beta lactam antibiotics?

Back 1

They interfere with the synthesis of the bacterial cell wall peptidoglycan. They bind covalently to a to penicillin-binding protein (PBP) and inhibits its function so the synthesis and crosslinking of peptidoglycans is compromised. This causes the bacteriall cell to lyse.

Front 2

Name the basic penicillins and how their are administered

Back 2

Penicillin G - Given IVPenicillin V - Orally. Good oral bioavailability and acid resistant.

Front 3

Name penicillinase resistant penicillins (antistaphylococcal)

Back 3

- Methicilin (not used)- Nafcilin- Oxacilin- Cloxacilin

Front 4

Name aminopenicillins (broad sprectrum)

Back 4

- Ampicillin- Amoxicillin

Front 5

Name antipseudomonal penicillins (ultra-broad spectrum)

Back 5

- Carbenicillin- Ticarcillin

Front 6

Name ureidopenicillins

Back 6

- Piperacillin

Front 7

There are 3 methods of resistance against penicillins. Describe how.

Back 7

1. Some bacteria produce penicillinase which is a specific beta-lactamase. This enzyme cleaves penicillin and deactivates it.
2. Bacteria may have mutated PBP which have lower affinity for penicillins than normal. The antibiotic cannot bind to it.
3. Some gram negatives have outer membrane proteins that prevent penicillins from entering.

Front 8

Which penicillins are mostly given IV?

Back 8

Penicillin G and piperacillin

Front 9

How are penicillins distributed and excreted?

Back 9

They are well distributed in extracellular space, but dont penetrate into intracellular space, prostate, eyes and CNS (except for meningitis).
Most of them are excreted unchaged by tubular secretion. Broad sprectrum can also excrete into bile.

Front 10

Side effects of penicillins?

Back 10

- Penicillin allergy which can lead to anaphylaxis, bronchospasm, interstitial nephritis and convulsions.
- GI symptoms- Nausea- Skin rash- Fever

Front 11

Name 1. generation cephalosporins and their use

Back 11

Cefalexin, cefalotin, cefazoline
Cefazoline is used as perioperative prophylaxis

Front 12

Name 2. generation cephalosporins and their use

Back 12

Cefaclor
Upper and lower respiratory tract infections

Front 13

Name 3. generation cephalosporins

Back 13

Ceftriaxone, cefixime, cefotaxime
Urinary tract and respiratory tract infections (nosocomial), meningitis, gonorrhea and pseudomonas.

Front 14

Name 4. generation cephalosporin and its use

Back 14

Cefepime
Used in case of severe infections or resistance to 3. generation cephalosporins.

Front 15

Name 5. generation cephalosporins and its use

Back 15

Ceftaroline
MRSA

Front 16

Describe the methods of resistance against cephalosporins

Back 16

1) Almost all gram negatives produce beta-lactamase against cephalosporins (but not penicillins).
2) Other membrane proteins can prevent cephalosporins from entering the bacterial cell.

Front 17

Pharmacokinetics of cefriaxone?

Back 17

- It is excreted into bile.- It binds stronly to albumin, and can displace other drugs.- Has half-life of 6-8 hours (while other cephalosporins have 1-2 hours).

Front 18

Side effects of cephalosporins?

Back 18

- Hypersensitivity reactions, where 5-7 % of people have cross-link allergy with penicillins.

- Nephrotoxicity together with aminoglycosides.
- GI symptoms

- Some have disulfiram-like effect when taken with alcohol.
- Some have coumarin-like effect