Evaluation of phenotypic characteristics for differentiation of enterococcal species using an example based algorithm

A computer based rule-generation system of Inductive Learning by Logic Mini mization (ILLM) was used to determine the sufficient set of biochemical rea ctions and necessary conditions that have to be fulfilled for correct diffe rentiation of enterococci recovered from humans. The simplest combination o f physiological tests for differentiation Enterococcus faecalis from all ot her enterococcal species consisted of only 3 reactions. Reactions that test ed the ability of acidification D-xylose, mannitol, L-arabinose and Na-pyru vate were useful for delineation of both E. faecalis and E. faecium from al l other enteroococi. For differentiation of all 12 currently known clinical ly significant species of enterococci any one of 3 sets of nine tests sugge sted by ILLM could be used. The tests suggested by ILLM were applied to 153 isolates of enteroccoci recovered at our Department of Microbiology and al l E. faecalis (138, 90.2%), E. faecium (13, 8.5%) and E. avium strains (2, 1.3%) were correctly differentiated. (C) 2000 Elsevier Science Inc. All rig hts reserved.