Abstract

BLANCO, María Alejandra; MONACO, María Belén  and  LOPARDO, Horacio Angel. Evaluation of an automated system for identifying enterococcal species. Acta bioquím. clín. latinoam. [online]. 2010, vol.44, n.2, pp.239-242. ISSN 0325-2957.

It has been demonstrated that the Vitek system is almost equivalent to conventional biochemical tests for identifying clinical isolates of Enterococcus spp. to the species level. However its performance is uncertain when less frequently found species are being identified. In the present study the ability of a commercial system (Vitek system) to identify enterococcal species was evaluated and compared to the conventional scheme. A total of 100 isolates of Enterococcus were tested: Enterococcus faecalis (25), Enterococcus faecium (25), Enterococcus gallinarum (21), Enterococcus casseliflavus (2), Enterococcus raffinosus (16), Enterococcus durans (4), Enterococcus hirae (2), Enterococcus mundtii (1) and Enterococcus avium (4). It is considered that one isolate was correctly identified when the percentage of the first choice was over 90% by the Vitek system. When this percentage was lower: (a) database test, (b) final point test, and/or (c) additional tests (alpha-methyl-D-glucopyranoside and motility) were analyzed. Of the 100 tested isolates, 56 were correctly identified using no additional tests. Using a corrective action a, b and c, the percentage increased to 85%. In conclusion, the use of Vitek version VTK-R 9.01 is not a reliable method for identification of enterococci unless the method described in this study be applied.

Keywords : Vitek; Enterococcus; Identification.

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