title: The contribution of antibiotic resistance mechanisms in clinical Burkholderia cepacia complex isolates: an emphasis on efflux pump activity.
abstract: Due to the limited information of the contribution of various antibiotic resistance mechanisms in clinical Burkholderia cepacia complex isolates, Antibiotic resistance mechanisms, including integron analysis, identification of quinolone resistance-determining region mutations, measurement of efflux pump activity, and sequence analysis of efflux pump regulators, were investigated in 66 clinical B. cepacia complex isolates. Species were identified via recA-RFLP and MALDI-TOF. Four genomovars were identified by recA-RFLP. B. cenocepacia (genomovar III) was the most prevalent genomovar (90.1%). Most isolates (60/66, 90.9%) were correctly identified by MALDI-TOF analysis. Clonal relatedness determined by PFGE analysis revealed 30 pulsotypes, including two major pulsotypes that comprised 22.7% and 18.2% of the isolates, respectively. Seventeen (25.8%) isolates harboured class 1 integron with various combinations of resistance genes. Among six levofloxacin-resistant isolates, five had single-base substitutions in the gyrA gene and three demonstrated efflux pump activities. Among the 42 isolates exhibiting resistance to at least one antimicrobial agent, 94.4% ceftazidime-resistant isolates (17/18) and 72.7% chloramphenicol-resistant isolates (16/22) demonstrated efflux pump activity. Quantitation of efflux pump RNA level and sequence analysis revealed that over-expression of the RND-3 efflux pump was attributable to specific mutations in the RND-3 efflux pump regulator gene. In conclusion, high-level expression of efflux pumps is prevalent in B. cepacia complex isolates. Mutations in the RND-3 efflux pump regulator gene are the major cause of efflux pump activity, resulting in the resistance to antibiotics in clinical B. cepacia complex isolates.
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC; Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, ROC.
authors.forename: Sung-Pin
authors.initials: SP
authors.lastname: Tseng
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Wan-Chi
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Liang
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Yin-Shiou
authors.initials: YS
authors.lastname: Lin
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Huang
authors.affiliation: College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Chung-Yu
authors.initials: CY
authors.lastname: Chang
authors.affiliation: Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Yu-Chang
authors.initials: YC
authors.lastname: Tyan
authors.affiliation: Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, ROC; College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC; Department of Internal Medicine, Kaohsiung Medical University Hospital, Taiwan, ROC.
authors.forename: Po-Liang
authors.initials: PL
authors.lastname: Lu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D042602:Burkholderia cepacia complex / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D006801:Humans; D032023:Integrons / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins