Dataset Information


Novel mechanism responsible for high-level macrolide resistance in Moraxella catarrhalis.

ABSTRACT: Background:High-level macrolide-resistant Moraxella catarrhalis strains have been isolated; however, the underlying mechanism has not been well elucidated. We investigated the role of mutations in the 23S rRNA gene and the L4 and L22 ribosomal proteins using spontaneous erythromycin-resistant mutants and transformants. Materials and methods:The erythromycin-susceptible M. catarrhalis ATCC25238 and clinical isolate Mc19 were used as parental strains. To obtain spontaneous erythromycin-resistant mutants, in vitro stepwise selection was performed using brain-heart infusion agar plates containing various concentrations of erythromycin. The role of the mutations identified in the spontaneous mutants was validated using transformation experiments. Results:We obtained two spontaneous mutants with high-level resistance to erythromycin, S25-32-af10 and S19-256-af10, from ATCC25238 and Mc19, respectively. S25-32-af10 exhibited mutations of Q61R in L4 and Insertion98SRADRIS in L22. S19-256-af10 exhibited three C2611T-mutated alleles in the 23S rRNA gene and G65A in L4. Transformants with single mutations identified in S25-32-af10 or S19-256-af10 showed higher erythromycin and azithromycin minimum inhibitory concentrations (MICs) than those of each parental strain. However, transformants with multiple mutations identified in S25-32-af10 or S19-256-af10 showed macrolide MICs similar to those of each parental strain. Conclusion:Our results provide the first evidence suggesting that Q61R in L4 and Insertion98SRADRIS in L22 are involved in the synergistic acquisition of high-level resistance to both 14- and 15-member macrolides, and that C2611T in the 23S rRNA gene and G65A in L4 also synergistically contribute toward conferring high-level 14-member macrolide resistance to M. catarrhalis.


PROVIDER: S-EPMC6219419 | BioStudies | 2018-01-01

REPOSITORIES: biostudies

Similar Datasets

2009-01-01 | S-EPMC2644216 | BioStudies
1000-01-01 | S-EPMC2229831 | BioStudies
2006-01-01 | S-EPMC1635205 | BioStudies
1000-01-01 | S-EPMC2666033 | BioStudies
2017-01-01 | S-EPMC5328525 | BioStudies
2004-01-01 | S-EPMC529214 | BioStudies
2004-01-01 | S-EPMC528798 | BioStudies
2005-01-01 | S-EPMC1168676 | BioStudies
2018-01-01 | S-EPMC6057423 | BioStudies
2013-01-01 | S-EPMC3591901 | BioStudies