1. D-4010
48th Interscience Conference on Antimicrobial Agents and Chemotherapy
October 25-28, 2008.
Washington, DC
Evaluation of an Automated System in Identification of Burkholderia Species R. A. Howe1, E. Mahenthiralingham2, M. Wootton1 1NPHS Microbiology, University Hospital Wales, Cardiff, UK. 2School of Biosciences, Cardiff University, Cardiff, UK.
Introduction
Materials and Methods
Table: Identification by PHX of known Burkholderia spp.
Burkholderia cenocepacia is the most prominent species of the B. cepacia complex (Bcc), a group of nine closely related and difficult to identify species that cause serious infections in patients with cystic fibrosis. B. cepacia genomovar I, Burkholderia multivorans (genomovar II), Burkholderia cenocepacia (lineage III-A and III-B), Burkholderia stabilis (genomovar IV) and Burkholderia vietnamiensis (genomovar V) cause the large majority of infections in CF patients. Automated identification systems are becoming increasingly used in diagnostic laboratories as a sole means to identify bacteria. This study aims to evaluate the PhoenixTM (PHX) automated identification system for identification and differentiation of Burkholderia spp
An international collection of 108 Bcc, genetically characterised by Multi-locus Sequence Typing (MLST), was studied. The collection included all established species plus additional genomovars, including B. cenocepacia, B. cepacia, B. multivorans, B. vietnamensis and B. stabilis from Cystic fibrosis and non cystic fibrosis origin (Table 1). Isolates were initially subcultured onto Tryptone Soya agar (TSA) then onto Blood agar. All isolates were tested on the PHX using Gram negative combi panels (NMIC/ID 65) according to manufacturer’s recommendations. The identification according to PHX was compared against that achieved by Multi Locus Sequence Typing (MLST). .
Results
Conclusions
Ultimately all strains were correctly identified to genus level although, for 16 strains, PHX gave “no identification” on initial testing; and it took 5 tests to obtain identification for 1 strain. Identification results are given in the table. Only 65% of B. cenocepacia and 20% of B. multivorans were correctly identified to species level.
The PHX automated system does not misidentify Burkholderia spp. at genus level.
However it may fail to give an identification
Alternative methods are required to establish the important species-level identification.
Table 1: Origin of isolates used
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