‘In-vitro’ interaction of cefoxitin with other antimicrobial agents against enterobacteriaceae

The ‘in-vitro’ activity of cefoxitin associated with ampicillin, carbenicillin, gentamicin, amikacin, fosfomycin or chloramphenicol was tested against clinical isolates of Escherichia coli, Kiebsiella spp., Enterobacter spp., Serratia marcescens and indole-positive Proteus. A remarkable synergy was found with the pairs cefoxitin + fosfomycin (85·5%) and cefoxitin + ampicillin (74·5%). Less synergistic effect was observed in the combinations of cefoxitin with carbenicillin (40%), chloramphenicol (44·2%), amikacin (37·7%) or gentamicin (16·3%). Antagonism was found in the combination of cefoxitin + carbenicillin (22·7%) and cefoxitin + chioramphenicol (7·1%).