[Antibacterial activity of mecillinam against E. coli isolated from urinary tract infections (author's transl)]

We studied susceptibility of 100 strains of clinically isolated E. coli by disc method to mecillinam. When inoculum size on agar plate was adjusted to 10(6) cells/ml and 10(9) cells/ml, respectively 96% and 63% strains were judged sensitive. Thus, in case of mecillinam MIC value as well as susceptibility tested by disc method highly depend on inoculum size and in the hospital laboratory inoculum size on agar plate should be carefully controlled even if it will be troublesome for routine disc examination. As it is suggested that clinical effectiveness of mecillinam will correspond to the result of 10(6) cells/ml inoculum size, we think the inoculum size should be adjusted 19(6) cells/l during the laboratory disc study.