Lee Mei-Feng, Chen Yen-Hsu, Peng Chien-Fang
Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Int J Antimicrob Agents. 2009 Mar;33(3):216-22. doi: 10.1016/j.ijantimicag.2008.09.017. Epub 2008 Dec 11.
Integron-mediated multidrug resistance in Salmonellaenterica serovar Choleraesuis poses a major concern in human salmonellosis in Taiwan. In this study, 71 strains of S. Choleraesuis harbouring a class 1 integron from humans and animals were characterised for detection of integrons, gene cassettes and the spvC virulence gene using molecular genetic techniques. All 71 strains tested were negative for class 2 and 3 integrons. Fifty-eight (81.7%) of the isolates harboured a class 1 integron with different gene cassettes, including dfr12-orfF-aadA2 in 50 strains, dfrA1-UN in 7 strains and aadA1 in 1 strain. Among the 71 isolates, 1 isolate of S. Choleraesuis H40 harboured two class 1 integrons, the first integron with the dfr12-orfF-aadA2 gene cassette and the second integron with a novel single gene cassette aadA22, a new variant of the aadA gene family. Moreover, 13 of the 71 isolates were negatively amplified by 5'-CS and 3'-CS specific primer pairs and represented a novel gene cassette array of sat-psp-aadA2-cmlA1-aadA1-like-qacH-tnp-sul3 in class 1 integrons. In mating experiments, the transferability of integron-mediated drug resistance in S. Choleraesuis isolates was demonstrated. The class 1 integron-borne gene cassette dfr12-orfF-aadA2 was characterised as becoming predominant in multidrug-resistant S. Choleraesuis isolates. Furthermore, both the dfrA1-UN gene cassette and the sul3-associated novel gene cassette were also identified in the S. Choleraesuis isolates. To date, this is the first report describing the dissemination of a sul3-associated integron in S. Choleraesuis isolates in Taiwan.
整合子介导的猪霍乱沙门氏菌多重耐药性是台湾地区人类沙门氏菌病的一个主要问题。在本研究中，利用分子遗传学技术对71株来自人和动物的携带1类整合子的猪霍乱沙门氏菌菌株进行了整合子、基因盒和spvC毒力基因检测。所有71株受试菌株的2类和3类整合子检测均为阴性。58株（81.7%）分离株携带1类整合子及不同的基因盒，其中50株含有dfr12-orfF-aadA2，7株含有dfrA1-UN，1株含有aadA1。在71株分离株中，1株猪霍乱沙门氏菌H40携带两个1类整合子，第一个整合子含有dfr12-orfF-aadA2基因盒，第二个整合子含有一个新的单基因盒aadA22，这是aadA基因家族的一个新变体。此外，71株分离株中有13株经5'-CS和3'-CS特异性引物对扩增为阴性，代表1类整合子中一种新的基因盒阵列sat-psp-aadA2-cmlA1-aadA1样-qacH-tnp-sul3。在接合实验中，证明了猪霍乱沙门氏菌分离株中整合子介导的耐药性可转移。1类整合子携带的基因盒dfr12-orfF-aadA2在多重耐药猪霍乱沙门氏菌分离株中占主导地位。此外，在猪霍乱沙门氏菌分离株中还鉴定出了dfrA1-UN基因盒和与sul3相关的新基因盒。迄今为止，这是首次报道台湾地区猪霍乱沙门氏菌分离株中与sul3相关的整合子的传播情况。
