Interpretive criteria for susceptibility testing of coagulase-negative staphylococci with special reference to netilmicin.

Antibiotic susceptibility of 171 isolates of coagulase-negative staphylococci from 66 preterm infants at a neonatal intensive care unit was tested by the microbroth dilution method. Results were interpreted according to DIN as well as according to NCCLS. Because of the bimodal distribution of MIC values within the CNS population tested, results of susceptibility interpretation according to DIN were identical to NCCLS with the exception of netilmicin (NCCLS: 89% susceptibility; DIN: 16% susceptibility). Since netilmicin is frequently used for treatment of infections caused by coagulase-negative staphylococci, this difference may be of clinical significance.