Differences in genomic macrorestriction patterns of arabinose-positive (Burkholderia thailandensis) and arabinose-negative Burkholderia pseudomallei

We reported previously two biochemically and antigenically distinct biotype s of Burkholderia pseudomallei. These two distinct biotypes could be distin guished by their ability to assimilate L-arabinose. Some B. pseudomallei is olated from soil samples could utilize this substrate (Ara(+)), whereas the other soil isolates and all clinical isolates could not (Ara(-)). Only the Ara(-) isolates were virulent in animals and reacted with monoclonal antib ody directed at the surface envelope, most likely the exopolysaccharide com ponent. In the present study, pulsed-held gel electrophoresis was employed for karyotyping of these previously identified B, pseudomallei strains. We demonstrate here that the DNA macrorestriction pattern allows the different iation between B, pseudomallei, which can assimilate L-arabinose, and the p roposed B, thailandensis, which cannot do so. Bacterial strains from 80 mel ioidosis patients and 33 soil samples were examined by genomic DNA digestio n with NcoI. Two major reproducible restriction patterns were observed. All clinical (Ara(-)) isolates and 9 Ara(-) soil isolates exhibited macrorestr iction pattern I (MPI), while 24 soil isolates (Ara(+)) from central and no rtheastern Thailand displayed macrorestriction pattern II (MPII). The study here demonstrated pulsed-field gel electrophoresis to be a useful tool in epidemiological investigation possibly distinguishing virulent B, pseudomal lei from avirulent B. thailandensis or even identifying closely related spe cies of Burkholderia.