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., Ro seto degli Abruzzi, Teramo, Italy) were compared with those of convent ional biochemical methods to identify 523 strains belonging to 16 diff erent human Staphylococcus species. Overall, 491 strains (93.9%) were correctly identified (percentage of identification, greater than or eq ual to 90.0), with 28 (5.4%) requiring supplementary tests for complet e identification. For 14 isolates (2.8%), the strains did not correspo nd to any key in the codebook and could not be identified by the manuf acturer's computer service. Only 18 isolates (3.4%) were misidentified . The system is simple to use, is easy to handle, gives highly reprodu cible results, and is inexpensive. With the inclusion of more discrimi nating tests and adjustment in supplementary code numbers for some spe cies, such as Staphylococcus lugdunensis and Staphylococcus schleiferi , Staf-Sistem 18-R is a suitable alternative for identification of hum an coagulase-positive and coagulase-negative Staphylococcus species in microbiological laboratories.