Lincocin Classification
Lincocin (lincomycin) is a lincosamide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of susceptible bacteria. 1
Mechanism of Action
- Lincomycin binds specifically to the 23S RNA of the 50S ribosomal subunit, blocking bacterial protein synthesis and producing predominantly bacteriostatic effects in vitro 1
- This mechanism is identical to clindamycin, which is the semi-synthetic chlorinated derivative of lincomycin and belongs to the same lincosamide class 2, 3
- At higher concentrations achievable in vivo, lincosamides may exhibit bactericidal activity 4
Antimicrobial Spectrum
- Gram-positive coverage: Lincomycin demonstrates activity against Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, viridans group streptococci, and Corynebacterium diphtheriae 1
- Anaerobic coverage: Active against Clostridium tetani, Clostridium perfringens, and other anaerobes 1
- Notable gaps: Lincomycin is NOT active against Haemophilus influenzae and Moraxella catarrhalis, which distinguishes it from broader-spectrum agents 2
Resistance Patterns
- Cross-resistance exists between lincomycin and clindamycin due to their shared mechanism 1
- Resistance most commonly occurs through methylation of specific nucleotides in the 23S RNA of the 50S ribosomal subunit, which can confer cross-resistance to macrolides and streptogramins B (MLSB phenotype) 1, 3
- Macrolide-resistant isolates should be tested for inducible resistance to lincomycin/clindamycin using the D-zone test 1
Clinical Context
- Lincomycin is produced by Streptomyces lincolnensis and was the original lincosamide antibiotic 1, 5
- Clindamycin has largely replaced lincomycin in clinical practice due to superior activity, particularly against anaerobic infections 6, 4
- The lincosamide class is structurally distinct from macrolides despite sharing the same ribosomal binding site 2