title: Global emergence of trimethoprim/sulfamethoxazole resistance in Stenotrophomonas maltophilia mediated by acquisition of sul genes.
abstract: Trimethoprim/sulfamethoxazole (TMP/SMX) resistance remains a serious threat in the treatment of Stenotrophomonas maltophilia infections. We analyzed an international collection of 55 S. maltophilia TMP/SMX-sensitive (S) (n=30) and -resistant (R) (n=25) strains for integrons; sul1, sul2 and dhfr genes; and insertion element common region (ISCR) elements. sul1, as part of a class 1 integron, was detected in 17 of 25 TMP/SMX-R. Nine TMP/SMX-R strains carried sul2; 7 were on large plasmids. Five TMP/SMX-R isolates were positive for ISCR2, and 4 were linked to sul2; 2 others possessed ISCR3. Two ISCR2s were adjacent to floR. Six TMP/SMX-S isolates harbored novel ISCR elements, ISCR9 and ISCR10. Linkage of ISCR3, ISCR9, and ISCR10 to sul2 and dhfr genes was not demonstrated. The data from this study indicate that class 1 integrons and ISCR elements linked to sul2 genes can mediate TMP/SMX resistance in S. maltophilia and are geographically widespread, findings that reinforce the need for ongoing resistance surveillance.
authors.affiliation: School of Medicine at Cardiff University, Cardiff, Wales, U.K.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Toleman
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bennett
authors.forename: David M C
authors.initials: DM
authors.lastname: Bennett
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Walsh
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D032023:Integrons; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000235:genetics; D014296:Trimethoprim Resistance / Q000235:genetics; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004251:DNA Transposable Elements; C491369:Sul2 protein, bacteria; D015662:Trimethoprim, Sulfamethoxazole Drug Combination