Oxacillin is a semisynthetic β-lactam antibiotic.1,2 It is active against clinical isolates of methicillin-susceptible S. aureus and penicillin-susceptible S. pneumoniae, as well as group A, group B, and viridans group streptococci with MIC90 values ranging from 0.06 to 2 ?g/ml in vitro.3 Oxacillin is less effective toward other bacteria with MIC90 values of greater than 16 ?g/ml for S. epidermidis, S. haemolyticus, E. faecalis, E. faecium, methicillin-resistant S. aureus (MRSA), and penicillin-intermediate and -resistant S. pneumoniae. It targets the bacterial cell wall, inhibiting S. pneumoniae penicillin-binding proteins 1a, 1b, 2a, 2b, and 3 in vitro with IC50 values ranging from 0.17 to 1.75 ?M.4,2 Oxacillin inhibits growth of S. aureus in a thigh model of infection in mice (ED50 = 45.19 mg/kg, s.c.).5 Formulations containing oxacillin have been used in the treatment of susceptible bacterial infections.
1.Hawks, G.H.Antibiotic therapy of staphylococcal infectionCan. Med. Assoc. J.93(16)848-853(1965) 2.Williamson, R., Hakenbeck, R., and Tomasz, A.In vivo interaction of β-lactam antibiotics with the penicillin-binding proteins of Streptococcus pneumoniaeAntimicrob. Agents Chemother.18(4)629-637(1980) 3.Milatovic, D., Schmitz, F.J., Verhoef, J., et al.Activities of the glycylcycline tigecycline (GAR-936) against 1,924 recent European clinical bacterial isolatesAntimicrob. Agents Chemother.47(1)400-404(2003) 4.Balibar, C.J., Shen, X., McGuire, D., et al.cwrA, a gene that specifically responds to cell wall damage in Staphylococcus aureusMicrobiology156(Pt 5)1372-1383(2010) 5.Rodriguez, C.A., Agudelo, M., Zuluaga, A.F., et al.In vitro and in vivo comparison of the anti-staphylococcal efficacy of generic products and the innovator of oxacillinBMC Infect. Dis.10(153)(2010)