Trunck, Lily A. and Propst, Katie L. and Wuthiekanun, Vanaporn and Tuanyok, Apichai and Beckstrom-Sternberg, Stephen M and Beckstrom-Sternberg, James S. and Peacock, Sharon J. and Keim, Paul and Dow, Steven W. and Schweizer, Herbert P. (2009) Molecular basis of rare aminoglycoside susceptibility and pathogenesis of Burkholderia pseudomallei clinical isolates from Thailand. PLoS Neglected Tropical Diseases, 3 (9). e0000519. ISSN 1935-2727
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Abstract
Background: Burkholderia pseudomallei is intrinsically resistant to aminoglycosides and macrolides, mostly due to AmrAB-OprA efflux pump expression. We investigated the molecular mechanisms of aminoglycoside susceptibility exhibited by Thai strains 708a, 2188a, and 3799a. Methodology/Principal Findings: qRT-PCR revealed absence of amrB transcripts in 708a and greatly reduced levels in 2188a and 3799a. Serial passage on increasing gentamicin concentrations yielded 2188a and 3799a mutants that became simultaneously resistant to other aminoglycosides and macrolides, whereas such mutants could not be obtained with 708a. Transcript analysis showed that the resistance of the 2188a and 3799a mutants was due to upregulation of amrAB-oprA expression by unknown mechanism(s). Use of a PCR walking strategy revealed that the amrAB-oprA operon was missing in 708a and that this loss was associated with deletion of more than 70 kb of genetic material. Rescue of the amrAB-oprB region from a 708a fosmid library and sequencing showed the presence of a large chromosome 1 deletion (131 kb and 141 kb compared to strains K96243 and 1710b, respectively). This deletion not only removed the amrAB-oprA operon, but also the entire gene clusters for malleobactin and cobalamin synthesis. Other genes deleted included the anaerobic arginine deiminase pathway, putative type 1 fimbriae and secreted chitinase. Whole genome sequencing and PCR analysis confirmed absence of these genes from 708a. Despite missing several putative virulence genes, 708a was fully virulent in a murine melioidosis model. Conclusions/Significance: Strain 708a may be a natural candidate for genetic manipulation experiments that use Select Agent compliant antibiotics for selection and validates the use of laboratory-constructed D (amrAB-oprA) mutants in such experiments.
| Item Type: | Article |
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| ID number or DOI: | 10.1371/journal.pntd.0000519 |
| Related URLs: | |
| Subjects: | Q Science > QH Natural history > QH426 Genetics Q Science > QR Microbiology |
| NAU Depositing Author Academic Status: | Faculty/Staff |
| Department/Unit: | Research Centers > Center for Microbial Genetics and Genomics |
| Date Deposited: | 14 Oct 2015 01:29 |
| URI: | http://openknowledge.nau.edu/id/eprint/691 |
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