Beta lactam ring binds to penicillin binding protein (transpeptidase) and
prevents crosslinking of bacterial peptidoglycan
inhibits cell wall synthesis

Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases) while cell wall assembly is arrested

Less bactericidal but stable to staph beta-lactamases

Inhibits Glycopeptide synthetase  prevents peptidoglycan formation in bacterial cell well
(Unlike penicillins, prevents the transfer and addition of the muramylpentapeptide
building blocks that make up the peptidoglycan molecule itself.)
May also alter membrane permeability and selectively inhibit RNA synthesis.
Antimicrobial activity Dependent on Duration above MIC, not concentration

bioavailabilty 50–70%
routes of administration PO, IV or IM
doses Usually given QID or TDS in up to 2g/day

bioavailabilty Oral: Poor; I.M.: Erratic; Intraperitoneal: ~38%
IV. dose loading 20mg/kg then 1-1.5g daily based on levels

penetration into CSF occurs with inflamed meninges only

Distributes widely in
body tissue and fluids, except for CSF, improved CSF penetration with inflamed meninges

up to 95% PB

~50% PB

Vd ~0.28 L/kg

Vd: 0.4-1 L/kg

Hepatic- active metab

Little or no metabolism

excretion Urine (50-65% as unchanged drug)

excretion via kidneys unchanged
Not effectively removed by dialysis

half life 0.75–1 hours, prolonged in anuria/renal impair

half life Biphasic half life, prolonged in renal fail. Mean t1/2 4-6hrs

Up to 10% of the population have allergies to penicillins. Due to the high
percentage excreted renally unchanged dose adjustment is required in low urine
output states. Severe cholestatic hepatitis has been reported idiosyncratically.

Hypersensitivity reactions including anaphylaxis.
Rapid infusion is associated with histamine release - red-man syndrome.
Ototoxicity rare, dose related. Nephrotoxicity has declined with improved formulations, usually resolves with cessation of drug

narrow spectrum but is
useful for treating staphlococci which are resistant to benpen due to beta-lactamase activity
It should not be used if the organism is sensitive to benpen as benpen is more bactericidal

active against most gram positive bacteria (including staphlycocci, streptococci, enterococci, listeria monocytogenes, clostridium sp, and Bacillus sp.), with limited gram negative activity.

ANTIBIOTIC:
PENICILLIN

ANTIBIOTIC:
GLYCOPEPTIDE

useful for treating staphlococci which are resistant to benpen due to beta-lactamase activity
. It is well absorbed from the gut but is given IV if the infection is serious. It should not be used if the organism is sensitive to benpen as
benpen is more bacteriocidal.

It possesses a broad spectrum of activity against gram positive bacteria including MRSA.
Acts synergistically with aminoglycosides, cephalosporins and rifampicin (although synergy testing required as vancomycin + cephalosporin may act antagonistically against some strains of staph epidermis)

Narrow spectrum, semisynthetic anti-staphylococcal penicillin

Tricyclic glycopeptide antibiotic produced by streptococcus orientalis

Level 1

Level 1

PO/IV. Tablet/Powder for reconstitution

Store at 2-8 degrees, clear solution. Slowly due to vessel irritation (& risk of red man syndrome).
Monitoring required to avoid toxic levels (aiming serum conc 15+/-3).

MRSA develop or acquire the gene mecA which synthesizes an additional penicillin binding protein that enables it to continue cell wall synthesis in the presence of a beta lactam drug

VanA resistance – gene mutation leading to decreased affinity of peptidoglycan precursors for vancomycin.
Induced by exposure to vanc / teicoplanin
Van B resistance – similar but only induced by vancomycin; strains may remain susceptible to teicoplanin