title: [Analysis of acquired resistance genes in Stenotrophomonas maltophilia].
abstract: BACKGROUND
  Stenotrophomonas maltophilia is a gram-negative bacillus and a nosocomial pathogen in immunocompromised patients. Trimethoprim/sulfamethoxazole (TMP/SMX) is the drug of choice for treating S. maltophilia infection; however, resistance to TMP/SMX is increasing. In this study, we investigated the relationship between the incidence of TMP/SMX resistance and the presence of sul genes and mobile elements.
  
  
  METHODS
  A total of 120 S. maltophilia isolates were collected from 3 university hospitals between April 2007 and April 2009. Antimicrobial susceptibilities were determined using the disk diffusion method. PCR and DNA sequencing were conducted for the detection of sul1, sul2, class 1 integron, and ISCR2 element. Repetitive extragenic palindromic sequence-based PCR (REP-PCR) was carried out to evaluate the genetic relatedness.
  
  
  RESULTS
  The TMP/SMX-resistant (R) isolates harbored a significantly higher proportion of sul1 gene and class 1 integron than TMP/SMX-susceptible (S) isolates (P<0.001). Seventeen of 28 isolates with sul1 also had a class 1 integron, but none of the isolates without sul1 had a class 1 integron. The identified gene cassettes within class 1 integrons include aacA4, aadA1, aac6'-II, and qac. None of the 120 isolates carried sul2, glmM, or ISCR2 element. REP-PCR did not show any genetic relatedness among the isolates.
  
  
  CONCLUSIONS
  In Korea, the resistance of S. maltophilia isolates to TMP/SMX is due to sul1 within a class 1 integron rather than to sul2. The class 1 integron also harbors multiple antibiotic resistance genes in addition to sul1, and therefore it could mediate multidrug resistance in S. maltophilia.
authors.affiliation: Department of Laboratory Medicine, Chungnam National University, Daejeon, Korea.
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Song
authors.forename: Ji Youn
authors.initials: JY
authors.lastname: Sung
authors.forename: Kye Chul
authors.initials: KC
authors.lastname: Kwon
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Hye Hyun
authors.initials: HH
authors.lastname: Cho
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Shin
authors.forename: Young Hyun
authors.initials: YH
authors.lastname: Ko
authors.forename: Ji Myung
authors.initials: JM
authors.lastname: Kim
authors.forename: Kyeong Seob
authors.initials: KS
authors.lastname: Shin
authors.forename: Sun Hoe
authors.initials: SH
authors.lastname: Koo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D006801:Humans; D032023:Integrons / Q000235:genetics; D016133:Polymerase Chain Reaction; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C491369:Sul2 protein, bacteria; D015662:Trimethoprim, Sulfamethoxazole Drug Combination