Netilmicin synergy with carbenicillin or cefamandole against Serratia.

Twenty clinical isolates of Serratia sp. were tested against netilmicin, gentamicin, carbenicillin and cefamandole alone (broth and agar dilution) and in combination (agar dilution). Broth and agar dilution minimal inhibitory concentrations agreed to within a two-fold dilution in 96% of the tests. Overall, 95% of the isolates were susceptible to netilmicin regardless of susceptibility to gentamicin or carbenicillin. Netilmicin-carbenicillin synergy was seen in 55% of the strains and netilmicin-cefamandole in 70%. These results indicate that combinations of netilmicin with carbenicillin or cefamandole may be clinically useful.