title: Loss of Methyltransferase Function and Increased Efflux Activity Leads to Doxycycline Resistance in Burkholderia pseudomallei.
abstract: The soil-dwelling bacteriumBurkholderia pseudomalleiis the causative agent of the potentially fatal disease melioidosis. The lack of a vaccine towardB. pseudomalleimeans that melioidosis treatment relies on prolonged antibiotic therapy, which can last up to 6 months in duration or longer. Due to intrinsic resistance, few antibiotics are effective againstB. pseudomalleiThe lengthy treatment regimen required increases the likelihood of resistance development, with subsequent potentially fatal relapse. Doxycycline (DOX) has historically played an important role in the eradication phase of melioidosis treatment. Both primary and acquired DOX resistances have been documented inB. pseudomallei; however, the molecular mechanisms underpinning DOX resistance have remained elusive. Here, we identify and functionally characterize the molecular mechanisms conferring acquired DOX resistance in an isogenicB. pseudomalleipair. Two synergistic mechanisms were identified. The first mutation occurred in a putativeS-adenosyl-l-methionine-dependent methyltransferase (encoded byBPSL3085), which we propose leads to altered ribosomal methylation, thereby decreasing DOX binding efficiency. The second mutation altered the function of the efflux pump repressor gene,amrR, resulting in increased expression of the resistance-nodulation-division efflux pump, AmrAB-OprA. Our findings highlight the diverse mechanisms by whichB. pseudomalleican become resistant to antibiotics used in melioidosis therapy and the need for resistance monitoring during treatment regimens, especially in patients with prolonged or recrudesced positive cultures forB. pseudomallei.
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Webb
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia.|Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.
authors.forename: Erin P
authors.identifier: 0000-0002-1079-4882
authors.initials: EP
authors.lastname: Price
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia.|Department of Infectious Diseases and Northern Territory Medical Program, Royal Darwin Hospital, Darwin, Northern Territory, Australia.
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Currie
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia derek.sarovich@menzies.edu.au.|Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.
authors.forename: Derek S
authors.identifier: 0000-0002-6944-3980
authors.initials: DS
authors.lastname: Sarovich
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016957:Burkholderia pseudomallei / Q000187:drug effects / Q000235:genetics; D004318:Doxycycline / Q000494:pharmacology*; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D008780:Methyltransferases; D004318:Doxycycline
keywords: AmrAB-OprA; BPSL3085; Burkholderia pseudomallei; SAM-dependent methyltransferase; amrR; antibiotic resistance; doxycycline