Evaluation of Staf-Sistem 18-R for identification of staphylococcal clinical isolates to the species level.

The accuracy and efficiency of Staf-Sistem 18-R (Liofilchem s.r.l., Roseto degli Abruzzi, Teramo, Italy) were compared with those of conventional biochemical methods to identify 523 strains belonging to 16 different human Staphylococcus species. Overall, 491 strains (93.9%) were correctly identified (percentage of identification, > or = 90.0), with 28 (5.4%) requiring supplementary tests for complete identification. For 14 isolates (2.8%), the strains did not correspond to any key in the codebook and could not be identified by the manufacturer's computer service. Only 18 isolates (3.4%) were misidentified. The system is simple to use, is easy to handle, gives highly reproducible results, and is inexpensive. With the inclusion of more discriminating tests and adjustment in supplementary code numbers for some species, such as Staphylococcus lugdunensis and Staphylococcus schleiferi, Staf-Sistem 18-R is a suitable alternative for identification of human coagulase-positive and coagulase-negative Staphylococcus species in microbiological laboratories.