Comparative Evaluation of the BD Phoenix and VITEK 2 Automated Instruments for Identification of Isolates of the Burkholderia cepacia Complex

Abstract

ABSTRACT We evaluated two new automated identification systems, the BD Phoenix (Becton Dickinson) and the VITEK 2 (bioMérieux), for identification of isolates of the Burkholderia cepacia complex (BCC). The test sample included 42 isolates of the highly virulent and epidemic genomovar III, 45 isolates of B. multivorans , and 47 isolates of other members of the BCC. Rates of correct identification by the BD Phoenix and VITEK 2 were similar when all BCC isolates were considered (50 and 53%, respectively) but differed markedly for genomovar III (71 and 38%; P < 0.01) and for B. multivorans (58 and 89%; P < 0.001). For the BD Phoenix as well as the VITEK 2, taking all 134 isolates of the BCC together, rates of correct identification of clinical isolates (56 and 55%, respectively; n = 85) were higher than those of environmental isolates (21 and 39%, respectively; n = 28). Clinical isolates of genomovar III ( n = 27) showed correct identification rates of 81% (BD Phoenix) and 48% (VITEK 2) ( P < 0.01). Rates of misidentification for BD Phoenix and VITEK 2 were 9 and 17% for genomovar III, 22 and 7% for B. multivorans , and 36 and 13% for the other BCC members ( P < 0.01), respectively. More than half of the isolates misidentified by each instrument were identified as Ralstonia pickettii , Ralstonia paucula (CDC IV C-2 group), Alcaligenes faecalis , Achromobacter spp., or, for the VITEK 2, “various nonfermenters.” This study reemphasizes that confirmatory identification of BCC, preferably by molecular methods, is highly recommended.