Our results using conventional Listeria identification tests are consistent with the subjectivity and ambiguity of phenotypic tests that have been discussed in the last decade [ 6, 7].
Conventional identification and growth tests were performed according to standard methods (15 ).
The isolates were characterized using conventional phenotypic Listeria identification tests and by the detection and analysis of L. monocytogenes-specific genes.
The cultures were identified on the basis of colony morphology, pigment production and characteristic biochemical reactions using both conventional and rapid identification tests (Quick strip).
We used an extended panel of biochemical and cultural tests for conventional identification.
One case reported an extended panel of biochemical and cultural tests for conventional identification that showed the absence of pigment and positive reactions to nitrate reductase, urease, and semiquantitative catalase as the most useful characteristics for tentative identification (15 ).
Data from an extended panel of biochemical and cultural tests for conventional identification have not been reported; however, the appearance of a scotochromogenic pale yellow pigment with growth at 45°C and a negative 3-day arylsulfatase test are in full agreement with our present and previous findings (7 ).
All conventional identification procedures, including cultural, biochemical, and enzymatic tests, failed to properly identify the species.
An extended panel of biochemical and cultural tests was used for conventional identification (10 ) (Table 2).
Clinical strains, primarily analyzed according to conventional identification strategies such as culture on selective agar (esculin, DNAse), biochemical testing (optochin, PYR, bacitracin, CAMP) including analytical profile index (API) and complementary agglutination tests were used.
