Penicillin binding proteins (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 antibiotics.
Penicillinase-resistant penicillins: Methicillin, nafcillin, and oxacillin.
Clavulanic acid and sulbactam: These are penicillin look-alikes that do not have antibacterial activity. Instead, they bind to beta-lactamase enzymes and protect penicillin from degradation.
Red man syndrome: Vancomycin induces flushing and vasodilation by causing histamine release from mast cells and basophils. It is NOT IgE-mediated.
R factor: R factor (resistance transfer factor) are plasmids that code for antibiotic resistance. One cell can have multiple copies of an 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. This may be due to failure to activate autolytic enzymes called murein hydrolases, which break down 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.