title: [Changes of resistant phenotype and CRISPR/Cas system of fourShigellastrains passaged for 90 times without antibiotics].
abstract: Objective:To explore the stability of resistant phenotypes and changes of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) gene system on fourShigellastrains in the absence of antibiotics.Methods:Four clinical isolatedShigellastrains that resistant to different antibiotics were consecutive passaged for 90 times without antibiotics. Agar dilution method was used to determine the minimum inhibitory concentration ofShigellastrains. After sequence analysis with PCR, CRISPR Finder and Clustal X 2.1 were applied to identify the changes of CRISPR loci in theShigellastrains.Results:After the consecutive transfer of 90 generations, sensitivity to certain antibiotics of fourShigellastrains with different drug resistant spectrums increased. Mel-sf1998024/zz resistance to ampicillin, cephalexin, cefotaxime, chloramphenicol decreased, mel-s2014026/sx resistance to norfloxacin, trimethoprim decreased, mel-sf2004004/sx drug resistance to ampicillin, cefuroxime, cefotaxime, chloramphenicol, trimethoprim decreased and mel-sf2013004/bj resistance to chloramphenicol decreased. The spacer of which matched gene codes Cas and its upstream repeat in 3'end of CRISPR3 got lost in mel-sf1998024/zz and mel-sf2013004/bj.Conclusions:Shigellastrains could reduce or lose their resistance to some antibiotics after consecutive transfers, without the interference of antibiotics. CRISPR3 locus had dynamic spacers inShigellastrains while CRISPR3 locus andcasgenes might have been co-evolved.
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: L J
authors.initials: LJ
authors.lastname: Hong
authors.affiliation: Henan Innovition Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China; Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: G C
authors.initials: GC
authors.lastname: Duan
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: W J
authors.initials: WJ
authors.lastname: Liang
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Yang
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Y L
authors.initials: YL
authors.lastname: Xi
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001426:Bacterial Proteins; D064113:CRISPR-Cas Systems; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D019295:Computational Biology / Q000379:methods*; D004269:DNA, Bacterial / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008957:Models, Genetic; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012760:Shigella / Q000145:classification / Q000187:drug effects* / Q000235:genetics*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial
keywords: CRISPR/Cas system; Drug resistance; Serial passage; Shigella; Without antibiotics