Identification of Staphylococcus epidermidis and Staphylococcus hominis from blood cultures by testing susceptibility to desferrioxamine.

Testing susceptibility to desferrioxamine has recently been described as a method for the identification of Staphylococcus epidermidis. This method was compared to a commercial test and the tube coagulase test for the identification of staphylococci from blood cultures and other fluid specimens. A total of 216 isolates was tested over a 13-month period. Sensitivity of the desferrioxamine test in identifying isolates of Staphylococcus epidermidis and Staphylococcus hominis was 97.3%, while specificity was 91.8%. When isolates displaying discrepant desferrioxamine results were characterized using recently described interpretive criteria, sensitivity and specificity of the desferrioxamine test improved to 100%. The desferrioxamine test was reliable, inexpensive and simple to perform, and should prove useful in the diagnostic laboratory.