[Combination between fosfomycin and oxacillin or cefotaxime against methicillin-resistant Staphylococci and Enterococci].

The resistance of Gram positive cocci to oxacillin and cephalosporins do not appear to be in relation with the synthesis of a beta-lactamase, thus fosfomycin (FOS) could enhance the action of beta-lactam antibiotics by blocking another stage of the peptidoglycan synthesis. When FOS is combined with oxacillin (OXA) or cefotaxime (CTX) against fosfomycin sensitive strains (25 S. aureus 4-16 mg/l, 20 S. epidermidis 2-32 mg/l and 20 Enterococci 16-64 mg/l) one can see a dramatic synergistic effect of these two combinations. Respectively with S. aureus, S. epidermidis and Enterococci, FIC indices are 0.17-0.39 and 0.43 for FOS-OXA and 0.29-0.47 and 0.29 for FOS-CTX. If one considers the CSF concentrations of these three antibiotics, the combination of fosfomycin with oxacillin or cefotaxime may be used in the treatment of meningitis due to methicillin resistant Staphylococci.