title: Arabinose assimilation defines a nonvirulent biotype of Burkholderia pseudomallei.
abstract: Two distinct types of Burkholderia pseudomallei, differentiated by the ability to assimilate L-arabinose but with similar morphologies and antigenicities, can be isolated from soil in Thailand. Approximately 25% of soil isolates from northeast Thailand were arabinose assimilators (Ara+), but in 1,200 sequentially studied patients, only arabinose "nonassimilators" (Ara-) caused melioidosis (P < 0.0001). In a murine model, there was a striking difference in virulence between Ara- and Ara+ B. pseudomallei. The mean (standard deviation) 50% lethal dose (LD[50]) inoculum for Ara- isolates was 182 (111) CFU/mouse compared with approximately 10(9) CFU/mouse for Ara+ soil isolates. There was no significant difference between the LD(50)s for clinical and soil Ara- isolates. All attempts to convert the biochemical phenotype by selective culture failed, which suggests that the biotype is stable.
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: M D
authors.initials: MD
authors.lastname: Smith
authors.forename: B J
authors.initials: BJ
authors.lastname: Angus
authors.forename: V
authors.initials: V
authors.lastname: Wuthiekanun
authors.forename: N J
authors.initials: NJ
authors.lastname: White
mesh_terms: D000818:Animals; D001089:Arabinose / Q000378:metabolism*; D015373:Bacterial Typing Techniques; D016957:Burkholderia pseudomallei / Q000145:classification* / Q000378:metabolism / Q000472:pathogenicity*; D006801:Humans; D007928:Lethal Dose 50; D008554:Melioidosis / Q000382:microbiology* / Q000401:mortality; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D011446:Prospective Studies; D012988:Soil Microbiology; D013785:Thailand
chemical_list: D001089:Arabinose