Spectinomycin is primarily a bacteriostatic antibiotic that inhibits protein synthesis in susceptible bacteria by binding to the 30S ribosomal subunit. Spectinomycin has activity against a wide variety of gram-positive and gram-negative bacteria, including E. coli, Klebsiella, Proteus, Enterobacter, Salmonella, Streptococci, Staphylococcus, and Mycoplasma. It has minimal activity against anaerobes, most strains of Pseudomonas, Chlamydia, or Treponema.