The sul1 gene in Stenotrophomonas maltophilia with high-level resistance to trimethoprim/sulfamethoxazole.
Emerging resistance to trimethoprim/sulfamethoxazole (SXT) poses a serious threat to the treatment of Stenotrophomonas maltophilia infections. We determined the prevalence and molecular characteristics of acquired SXT resistance in recent clinical S. maltophilia isolates obtained from Korea. A total of 252 clinical isolates of S. maltophilia were collected from 10 university hospitals in Korea between 2009 and 2010. Antimicrobial susceptibility was determined by using the CLSI agar dilution method. The sul1, sul2, and sul3 genes, integrons, insertion sequence common region (ISCR) elements, and dfrA genes were detected using PCR. The presence of the sul1 gene and integrons was confirmed through sequence analysis. Among the 32 SXT-resistant isolates, sul1 was detected in 23 isolates (72%), all of which demonstrated high-level resistance (≥64 mg/L) to SXT. The sul1 gene (varying in size and structure) was linked to class 1 integrons in 15 of the 23 isolates (65%) harboring this gene. None of the SXT-susceptible isolates or the SXT-resistant isolates with a minimum inhibitory concentration of 4 and 8 mg/L were positive for sul1. Moreover, the sul2, sul3, and dfrA genes or the ISCR elements were not detected. The sul1 gene may play an important role in the high-level SXT resistance observed in S. maltophilia.
Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea. ; Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Hae-Sun
HS
Chung
Department of Laboratory Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
Kyeongmi
K
Kim
Department of Laboratory Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
Sang Sook
SS
Hong
Department of Laboratory Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea. ; Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Seong Geun
SG
Hong
Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea. ; Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Kyungwon
K
Lee
Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea. ; Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Yunsop
Y
Chong
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000473:pathology; D006801:Humans; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015662:Trimethoprim, Sulfamethoxazole Drug Combination
Class 1 integron; Stenotrophomonas maltophilia; Trimethoprim/sulfamethoxazole; sul