Clinically significant differences in antibiograms of morphologic variants of blood culture isolates.

The present environment of cost containment frequently forces laboratories to reassess various strategies for the diagnostic work-up of patient specimens. The necessity for the performance of antimicrobial susceptibility testing on all morphologic variants of blood culture isolates was examined in this study. Over a 4-year period, of 143 such organisms that were identified, 56 (39%) exhibited clinically significant differences in antibiogram profiles. Coagulase-negative Staphylococcus represented the largest proportion of isolates (n = 115), 39% of which demonstrated clinically significant differences in antibiograms. The authors conclude that these results justify the current practice in their laboratory of performing separate antimicrobial susceptibility testing on all morphologic variants of isolates.