Lincosamide

Discovery

The first lincosamide compound, lincomycin, was isolated from Streptomyces lincolnensis, found in a soil sample from Lincoln, Nebraska, (hence the name) (Spížek and Řezanka, 2017). The biosynthesis of lincomycin is facilitated by the enzyme lincosamide synthetase and is unusual since it combines non-ribosomal peptide synthetase (NRPS) components with amino sugars (Spížek and Řezanka, 2017). While several Streptomyces species make lincosamides, the semi-synthetic derivatives (e.g., clindamycin) are made from the natural product lincomycin (Matzov et al., 2017). Currently, the main lincosamide antibiotic used clinically is Clindamycin, which interferes with protein synthesis.

Clindamycin (approved by the US FDA in 1970) may be used against staphylococci, group A and B streptococci, Streptococcus pneumoniae, and most anaerobic bacterial infections (Schwarz et al., 2016). It also shows activity against several protozoa, such as Plasmodium spp. and Toxoplasma spp., but little activity against most aerobic gram-negative bacilli, Nocardia spp., Mycobacterium spp., as well as Enterococcus faecalis and Enterococcus faecium. Currently, lincosamides have very limited use in treating human infections. So, even though it is approved for veterinary medicine and is used to treat dogs and cats, it must not be used in animals consumed as food.

Learn more about protein synthesis.

Overview of Chemistry

Lincosamides are a small group of antibiotics with a chemical structure consisting of an amino acid and sugar moieties linked by a linker (Figure 1). For example, the first lincosamide, Lincomycin, consists of an unusual amino acid, propylhygric acid, linked by a peptide bond with a sugar, 6-amino-6,8-dideoxy-1-thio-d-erythro-α-d-galactopyranoside. The antibiotic binds at the peptidyltransferase center of bacterial ribosomes in the 50S subunit to inhibit peptide synthesis. They are readily soluble in water and chemically stable (Spízek and Rezanka, 2004).

Although the chemical structures of macrolides (e.g., erythromycin), lincosamides (e.g., lincomycin, clindamycin), and streptogramins are very different, their mechanism of action is identical (Spízek and Rezanka, 2004).

Learn more about clindamycin's action.

Figure 1. 2D structure of Lincosamides showing the key groups of this class of antibiotics - amino acid group (circled in magenta oval) and the sugar (circled in blue)

Types

Three kinds of lincosamide derivatives have been reported to date, including lincomycin (Figure 1A), clindamycin (Figure 1B), and pirlimycin (not shown here). Clindamycin is the chlorinated analog of lincomycin (Yang et al., 2024). Learn about how this antibiotic interacts with the ribosome.

Resistance

Although lincosamides are potent antibiotics against anaerobic bacteria and some protozoa, they exhibit resistance over time (Yang et al., 2024). These antibiotics play an important role in both human and veterinary clinical practice. Due to the extensive use of lincosamide antibiotics in veterinary clinics, resistance to macrolides and lincosamides is increasingly reported in clinical isolates of gram-positive bacteria.

The main type of resistance to lincomycin and clindamycin is the resistance that renders a sensitive microorganism resistant to macrolides, lincosamides, and streptogramin B (MLSB resistance). This type of resistance is associated with genes encoding methyltransferases modifying the common target site of macrolides and lincosamides, i.e., 23S ribosomal RNA (Spízek and Rezanka, 2004). Through ribosomal modification (e.g., mutations in the 50S ribosomal subunit's 23S rRNA), efflux of the antibiotic (e.g., due to the transfer of lsa, vga, or sal class genes), and drug inactivation (e.g., due to enzymatic nucleotidylation of the antibiotic, resistance to this class of antibiotics continues to grow. Note that the resistance rate of bacteria to clindamycin has shown an increasing trend in Asian countries in recent years (Yang et al., 2024).

Learn more about clindamycin resistance.

References

Matzov, D., Eyal, Z., Benhamou, R. I., Shalev-Benami, M., Halfon, Y., Krupkin, M., Zimmerman, E., Rozenberg, H., Bashan, A., Fridman, M., Yonath, A. (2017) Structural insights of lincosamides targeting the ribosome of Staphylococcus aureus. Nucleic Acids Res 45:10284–10292. https://doi.org/10.1093/nar/gkx658

Spízek, J., Rezanka, T. (2004) Lincomycin, clindamycin and their applications. Appl Microbiol Biotechnol. 64(4):455-64. https://doi.org/10.1007/s00253-003-1545-7

Spížek, J., Řezanka, T. (2017) Lincosamides: Chemical structure, biosynthesis, mechanism of action, resistance, and applications. Biochem Pharmacol. 133:20-28. https://doi.org/10.1016/j.bcp.2016.12.001

Schwarz, S., Shen, J., Kadlec, K., Wang, Y., Brenner, M. G., Feßler, A. T., Vester, B. (2016) Lincosamides, Streptogramins, Phenicols, and Pleuromutilins: Mode of Action and Mechanisms of Resistance. Cold Spring Harb Perspect Med. 6(11):a027037. https://doi.org/10.1101/cshperspect.a027037

Yang, Y., Xie, S., He, F., Xu, Y., Wang, Z., Ihsan, A., Wang, X. (2024) Recent development and fighting strategies for lincosamide antibiotic resistance. Clin Microbiol Rev. 37(2):e0016123. https://doi.org/10.1128/cmr.00161-23