title: Burkholderia pseudomallei animal and human isolates from Malaysia exhibit different phenotypic characteristics.
abstract: Burkholderia pseudomallei is a Gram-negative saprophytic soil bacterium, which is the etiologic agent of melioidosis, a severe and fatal infectious disease occurring in human and animals. Distinct clinical and animal isolates have been shown to exhibit differences in phenotypic trait such as growth rate, colony morphology, antimicrobial resistance, and virulence. This study was carried out to gain insight into the intrinsic differences between 4 clinical and 6 animal B. pseudomallei isolates from Malaysia. The 16S rRNA-encoding genes from these 10 isolates of B. pseudomallei were sequenced to confirm the identity of these isolates along with the avirulent Burkholderia thailandensis. The nucleotide sequences indicated that the 16S rRNA-encoding genes among the 10 B. pseudomallei isolates were identical to each other. However, the nucleotide sequence differences in the 16S rRNA-encoding genes appeared to be B. pseudomallei and B. thailandensis specific. The growth rate of all B. pseudomallei isolates was determined by generating growth curves at 37 degrees C for 72 h. The isolates were found to differ in growth rates with doubling time varying from 1.5 to 2.3 h. In addition, the B. pseudomallei isolates exhibited considerable variation in colony morphology when grown on Ashdown media, brain-heart infusion agar, and Luria-Bertani agar over 9 days of observation. Antimicrobial susceptibility tests indicated that 80% of the isolates examined were Amp(R) Cb(R) Kn(R) Gm(R) Chl(S) Te(S). Virulence of the B. pseudomallei clinical and animal isolates was evaluated in B. pseudomallei-susceptible BALB/c mice. Most of the clinical isolates were highly virulent. However, virulence did not correlate with isolate origin since 2 of the animal isolates were also highly virulent.
authors.affiliation: Faculty of Science and Technology, School of Biosciences and Biotechnology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia.
authors.forename: Song-Hua
authors.initials: SH
authors.lastname: Lee
authors.forename: Chan-Eng
authors.initials: CE
authors.lastname: Chong
authors.forename: Boon-San
authors.initials: BS
authors.lastname: Lim
authors.forename: San-Jiun
authors.initials: SJ
authors.lastname: Chai
authors.forename: Kin-Kit
authors.initials: KK
authors.lastname: Sam
authors.forename: Rahmah
authors.initials: R
authors.lastname: Mohamed
authors.forename: Sheila
authors.initials: S
authors.lastname: Nathan
mesh_terms: D000818:Animals; D001483:Base Sequence; D016957:Burkholderia pseudomallei / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004195:Disease Models, Animal; D020459:Genes, rRNA / Q000235:genetics; D006801:Humans; D008296:Malaysia; D008554:Melioidosis / Q000382:microbiology* / Q000662:veterinary*; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013154:Spleen / Q000382:microbiology; D016019:Survival Analysis; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S