Analysis of Acquired Resistance Genes in Stenotrophomonas maltophilia

作者：Song Jeong Hoon; Sung Ji Youn; Kwon Kye Chul; Park Jong Woo; Cho Hye Hyun; Shin So Yeon; Ko Young Hyun; Kim Ji Myung; Shin Kyeong Seob; Koo Sun Hoe^*

来源：Korean Journal of Laboratory Medicine, 2010, 30(3): 295-300.

DOI：10.3343/kjlm.2010.30.3.295

• Stenotrophomonas maltophilia
• Trimethoprim/sulfamethoxazole
• sul1 gene
• Class 1 integron

Background : Stenotrophomonas maltophilia is a grain-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 sulgenes 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. (Korean J Lab Med 2010;30:295-300)

• 出版日期2010-6