Spectinomycin

Spectinomycin is an aminocyclitol antibiotic produced by the soil actinomycete Streptomyces spectabilis. It belongs to a class of compounds that inhibit bacterial protein synthesis and has historically been used to treat certain sexually transmitted infections. Its clinical use has diminished in many regions due to evolving resistance and the availability of other agents.

The primary mechanism of spectinomycin is binding to the 30S ribosomal subunit, where it interferes with the translocation step of protein synthesis. By preventing movement of peptidyl-tRNA from the A site to the P site, spectinomycin effectively halts elongation. Unlike many aminoglycosides, it does not generally cause widespread misreading of mRNA, and its action is typically bacteriostatic rather than bactericidal for most pathogens.

Spectinomycin exhibits a relatively narrow spectrum. It is most active against Neisseria gonorrhoeae and has limited activity against other Gram-negative bacteria; it is not active against most Gram-positive organisms or anaerobes. It is poorly absorbed when given orally and is usually administered intramuscularly or intravenously. It is excreted largely unchanged by the kidneys.

Clinically, spectinomycin has been used primarily as a treatment option for gonorrhea in patients who are allergic to penicillin or other first-line therapies. Because resistance can develop and other effective agents are available, its use has declined in many guidelines, and it is not universally recommended as a first-line therapy.

Side effects are generally mild and can include injection-site reactions, hypersensitivity, and, rarely, nephrotoxicity or otoxicity. Resistance mechanisms include mutations in the 16S rRNA or ribosomal proteins that alter the drug’s binding site.