Lincomycin (Lincocin)

Overview

Lincomycin is an antibiotic indicated only for the treatment of serious infections and is typically reserved for use in cases of penicillin allergy or where penicillin is inappropriate.

Mechanism of Action

Lincomycin contains the unusual amino acid moiety propyl hygric acid linked to the sugar moiety α-methylthiolincosamine (α-MTL) that, like other lincosamides, functions as a structural analogue of the 3' end of L-Pro-Met-tRNA and deacylated-tRNA to interact with the 23S rRNA of the 50S bacterial ribosomal subunit. Detailed investigations into the mechanism of the related lincosamide clindamycin suggested a two-phase binding, instantaneously to the A-site with a shift in equilibrium towards the P-site over several seconds. This shift appears to be due to rotation of the propyl hygric acid moiety, while the α-MTL remains relatively stationary. Recent crystal structures of lincomycin in complex with the 50S ribosomal subunit of Staphylococcus aureus show that the α-MTL moiety forms hydrogen bonds with C2611, A2058, G2505, A2059, and G2503 of the 23S rRNA while the propyl hygric acid moiety interacts only through van der Waals contacts, suggesting it may be free to rotate similar to clindamycin. This mechanism is supported by the observation that the most common resistance mechanism, which also affects macrolides and streptogramin B (MSLB resistance) involves methylation of A2058; other resistance mechanisms similarly target residues such as A2058, A2059, and C2611.

Indications

Lincomycin is indicated for the treatment of serious bacterial infections by susceptible strains of streptococci, pneumococci, and staphylococci in patients who are allergic to penicillins or for situations in which a penicillin is deemed inappropriate. As with all antibacterial agents, lincomycin should only be used to treat infections proven or strongly suspected to be caused by susceptible bacteria.

• Serious Bacterial Infection