Additional information

Penicillin binding proteins or PBPs: The D Alanine D Alanine portion of the peptide chain is cross linked by glycine residues in the presence of Penicillin Binding Proteins. This strengthens the cell wall.

Beta lactams: Penicillins, Cephalosporins, Monobactams (Aztreonam) and Carbapenems (Imipenem, Meropenem) are Beta lactam antibiotic

Penicillinase resistant penicillins are Methicillin, Nafcillin, Oxacillin.

Clavulanic acid and sulbactam. They are Penicillin lookalikes that do not have antibacterial activity but bind to Beta lactamase enzymes and protect Penicillin from degradation.

Red man syndrome: Vancomycin induces flushing and vasodilation by histamine release from mast cells and basophils. It is NOT Ig E mediated.

R factor. R factor or resistance transfer factor are plasmids that code for antibiotic resistance. One cell can have multiple copies of R factor. They may be large (containing genes for resistance plus conjugation) or small (containing only the resistance genes). They can be transferred to other bacteria via conjugation.

Tolerance: bacteria may be able to grow in the presence of an antibiotic when growth is inhibited by the antibiotic but without the bacterium being killed. May be due to failure of activation of an autolytic enzyme called murein hydrolases which breakdown peptidoglycans.

Protoplasts: some bacteria may lose their cell walls and survive as protoplasts when exposed to penicillin. Penicillin is inactive against protoplast forms of bacteria.