title: Current Situation of Antimicrobial Resistance and Genetic Differences in Stenotrophomonas maltophilia Complex Isolates by Multilocus Variable Number of Tandem Repeat Analysis.
abstract: BACKGROUND
  Stenotrophomonas maltophilia is one of several opportunistic pathogens of growing significance. Several studies on the molecular epidemiology of S. maltophilia have shown clinical isolates to be genetically diverse.
  
  
  METHODS
  A total of 121 clinical isolates tentatively identified as S. malophilia from seven tertiary-care hospitals in Korea from 2007 to 2011 were included. Species and groups were identified using partial gyrB gene sequences and antimicrobial susceptibility testing was performed using a broth microdilution method. Multi locus variable number of tandem repeat analysis (MLVA) surveys are used for subtyping.
  
  
  RESULTS
  Based on partial gyrB gene sequences, 118 isolates were identified as belonging to the S. maltophilia complex. For all S. maltophilia isolates, the resistance rates to trimethoprime-sulfamethoxazole (TMP/SMX) and levofloxacin were the highest (both, 30.5%). Resistance rate to ceftazidime was 28.0%. 11.0% and 11.9% of 118 S. maltophilia isolates displayed resistance to piperacillin/tazobactam and tigecycline, respectively. Clade 1 and Clade 2 were definitely distinguished from the data of MLVA with amplification of loci. All 118 isolates were classified into several clusters as its identification.
  
  
  CONCLUSIONS
  Because of high resistance rates to TMP/SMX and levofloxacin, the clinical laboratory department should consider providing the data about other antimicrobial agents and treatment of S. maltophilia infections with a combination of antimicrobials can be considered in the current practice. The MLVA evaluated in this study provides a fast, portable, relatively low cost genotyping method that can be employed in genotypic linkage or transmission networks comparing to analysis of the gyrB gene.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Dankook University, Cheonan, Korea.
authors.forename: Ji Young
authors.identifier: http://orcid.org/0000-0003-4664-7048
authors.initials: JY
authors.lastname: Rhee
authors.affiliation: Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.|Asia Pacific Foundation for Infectious Diseases, Seoul, Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Song
authors.affiliation: Asia Pacific Foundation for Infectious Diseases, Seoul, Korea.|Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea. ksko@skku.edu.
authors.forename: Kwan Soo
authors.identifier: http://orcid.org/0000-0002-0978-1937
authors.initials: KS
authors.lastname: Ko
keywords: Multi locus variable number of tandem repeat analysis; Sternotrophomonas maltophilia; Trimethoprime-sulfamethoxazole