title: Expression of Sme efflux pumps and multilocus sequence typing in clinical isolates of Stenotrophomonas maltophilia.
abstract: BACKGROUND
  Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen, which causes infections that are often difficult to manage because of the inherent resistance of the pathogen to a variety of antimicrobial agents. In this study, we analyzed the expressions of smeABC and smeDEF and their correlation with antimicrobial susceptibility. We also evaluated the genetic relatedness and epidemiological links among 33 isolates of S. maltophilia.
  
  
  METHODS
  In total, 33 S. maltophilia strains were isolated from patients in a tertiary hospital in Daejeon. Minimum inhibitory concentrations (MICs) of 11 antimicrobial agents were determined by using agar dilution method and E-test (BioMérieux, France). Real-time PCR analysis was performed to evaluate the expression of the Sme efflux systems in the S. maltophilia isolates. Additionally, an epidemiological investigation was performed using multilocus sequence typing (MLST) assays.
  
  
  RESULTS
  The findings of susceptibility testing showed that the majority of the S. maltophilia isolates were resistant to β-lactams and aminoglycosides. Twenty-one clinical isolates overexpressed smeABC and showed high resistance to ciprofloxacin. Moreover, a high degree of genetic diversity was observed among the S. maltophilia isolates; 3 sequence types (STs) and 23 allelic profiles were observed.
  
  
  CONCLUSIONS
  The smeABC efflux pump was associated with multidrug resistance in clinical isolates of S. maltophilia. In particular, smeABC efflux pumps appear to perform an important role in ciprofloxacin resistance of S. maltophilia. The MLST scheme for S. maltophilia represents a discriminatory typing method with stable markers and is appropriate for studying population structures.
authors.affiliation: Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea.
authors.forename: Hye Hyun
authors.initials: HH
authors.lastname: Cho
authors.forename: Ji Youn
authors.initials: JY
authors.lastname: Sung
authors.forename: Kye Chul
authors.initials: KC
authors.lastname: Kwon
authors.forename: Sun Hoe
authors.initials: SH
authors.lastname: Koo
mesh_terms: D000483:Alleles; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015373:Bacterial Typing Techniques; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D015964:Gene Expression Regulation, Bacterial; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D020615:Stenotrophomonas maltophilia / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D002939:Ciprofloxacin