OBJECTIVES: To identify and characterize the mechanisms of high-level fluoroquinolone resistance in two strains of Bacillus anthracis following serial passage in increasing concentrations of fluoroquinolones. METHODS: Fluoroquinolone-resistant isolates of the Sterne and Russian Anthrax Vaccine STi strains were obtained following serial passage in the presence of increasing concentrations of four different fluoroquinolones. The quinolone-resistance-determining regions of the type II topoisomerase genes from the resistant strains were amplified by PCR and characterized by DNA sequence analysis. The MICs in the presence and absence of reserpine were determined using broth microdilution as a means of detecting active efflux. RESULTS: Single and double amino acid substitutions in the GyrA (Ser-85-Leu; Glu-89-Arg/Gly/Lys) and GrlA (Ser-81-Tyr; Val-96-Ala; Asn-70-Lys) were most common. A single amino acid substitution in GyrB (Asp-430-Asn) was also identified. Efflux only applied to isolates selected for by either levofloxacin or ofloxacin. CONCLUSIONS: Specific amino acid substitutions in the type II topoisomerase enzymes significantly contributed to the development of high-level fluoroquinolone resistance in B. anthracis. However, notable differences between the strains and the drugs tested were identified including the role of efflux and the numbers and types of mutations identified.
OBJECTIVES: To identify and characterize the mechanisms of high-level fluoroquinolone resistance in two strains of Bacillus anthracis following serial passage in increasing concentrations of fluoroquinolones. METHODS:Fluoroquinolone-resistant isolates of the Sterne and Russian Anthrax Vaccine STi strains were obtained following serial passage in the presence of increasing concentrations of four different fluoroquinolones. The quinolone-resistance-determining regions of the type II topoisomerase genes from the resistant strains were amplified by PCR and characterized by DNA sequence analysis. The MICs in the presence and absence of reserpine were determined using broth microdilution as a means of detecting active efflux. RESULTS: Single and double amino acid substitutions in the GyrA (Ser-85-Leu; Glu-89-Arg/Gly/Lys) and GrlA (Ser-81-Tyr; Val-96-Ala; Asn-70-Lys) were most common. A single amino acid substitution in GyrB (Asp-430-Asn) was also identified. Efflux only applied to isolates selected for by either levofloxacin or ofloxacin. CONCLUSIONS: Specific amino acid substitutions in the type II topoisomerase enzymes significantly contributed to the development of high-level fluoroquinolone resistance in B. anthracis. However, notable differences between the strains and the drugs tested were identified including the role of efflux and the numbers and types of mutations identified.
Authors: Katie J Aldred; Sylvia A McPherson; Pengfei Wang; Robert J Kerns; David E Graves; Charles L Turnbough; Neil Osheroff Journal: Biochemistry Date: 2011-12-16 Impact factor: 3.162
Authors: Katie J Aldred; Heidi A Schwanz; Gangqin Li; Sylvia A McPherson; Charles L Turnbough; Robert J Kerns; Neil Osheroff Journal: ACS Chem Biol Date: 2013-09-30 Impact factor: 5.100
Authors: Katie J Aldred; Heidi A Schwanz; Gangqin Li; Benjamin H Williamson; Sylvia A McPherson; Charles L Turnbough; Robert J Kerns; Neil Osheroff Journal: Biochemistry Date: 2015-01-23 Impact factor: 3.162
Authors: H S Heine; S V Shadomy; A E Boyer; L Chuvala; R Riggins; A Kesterson; J Myrick; J Craig; M G Candela; J R Barr; K Hendricks; W A Bower; H Walke; G L Drusano Journal: Antimicrob Agents Chemother Date: 2017-08-24 Impact factor: 5.191
Authors: Arnold Louie; Brian D VanScoy; David L Brown; Robert W Kulawy; Henry S Heine; George L Drusano Journal: Antimicrob Agents Chemother Date: 2011-12-12 Impact factor: 5.191
Authors: Melissa May; Shahila Mehboob; Debbie C Mulhearn; Zhiqiang Wang; Huidong Yu; Gregory R J Thatcher; Bernard D Santarsiero; Michael E Johnson; Andrew D Mesecar Journal: J Mol Biol Date: 2007-06-04 Impact factor: 5.469