Ho P L, Wong R C, Chow K H, Que T L
Division of Infectious Diseases, Department of Microbiology and Centre of Infection, The University of Hong Kong, Hong Kong, China.
Lett Appl Microbiol. 2009 Nov;49(5):627-34. doi: 10.1111/j.1472-765X.2009.02717.x. Epub 2009 Aug 18.
To compare the distribution of integrons and trimethoprim-sulfamethoxazole resistance genes among Escherichia coli isolates from humans and food-producing animals.
A collection of 174 multidrug-resistant E. coli isolates obtained from faecal samples of food-producing animals (n = 64) and humans (n = 59), and patients with urinary tract infections (n = 51) in Hong Kong during 2002-2004 were studied. The strains were analysed for their phylogenetic groups, the presence of sul genes (sul1 and sul2), integrons (intl1 and intl2) and class 1 integron-associated dfr cassette genes by PCR, restriction enzyme analysis and sequencing. Integrons were identified in 110 (63.2%) isolates. The prevalence of integrons was significantly different according to the specimen sources (animal faecal 84.4%, human faecal 67.8% and human urinary 31.4%) and phylogenetic groups (B1 80.8%, A 77.6%, D 54.1% and B2 11.5%). Faecal isolates (both human and animal) are more likely to belong to group A and B1. In contrast, most urinary isolates were either groups B2 and D. Among dfr containing isolates, dfrA1 and dfrA12 were almost exclusively found in strains of phylogenetic groups A and B1; and were present in animal and human faecal isolates. In contrast, dfrA17 was found in both faecal and urinary isolates and comprised strains from all phylogenetic groups. The sul1 and sul2 genes were equally prevalent among the isolates irrespective of the specimen source and phylogenetic group status. Pulsed-field gel electrophoresis analysis of isolates with identical cassette genes showed that they were genetically diverse.
More animal faecal isolates carry class 1 integrons than human faecal and human urinary isolates, and the distribution of phylogenetic groups is common across animal and human faecal isolates but different from human urinary isolates.
Commensal isolates from food-producing animals are an important reservoir for integrons carrying antibiotic resistance genes.
比较从人类和产食动物中分离出的大肠杆菌中整合子和甲氧苄啶 - 磺胺甲恶唑抗性基因的分布情况。
对2002年至2004年期间从香港的产食动物粪便样本（n = 64）、人类粪便样本（n = 59）以及尿路感染患者（n = 51）中获得的174株多重耐药大肠杆菌分离株进行研究。通过聚合酶链反应（PCR）、限制性内切酶分析和测序，对这些菌株进行系统发育组分析、sul基因（sul1和sul2）、整合子（intl1和intl2）以及1类整合子相关dfr盒基因的检测。在110株（63.2%）分离株中鉴定出整合子。根据标本来源（动物粪便84.4%、人类粪便67.8%和人类尿液31.4%）和系统发育组（B1 80.8%、A 77.6%、D 54.1%和B2 11.5%），整合子的流行率存在显著差异。粪便分离株（包括人类和动物）更可能属于A组和B1组。相比之下，大多数尿液分离株属于B2组和D组。在含有dfr的分离株中，dfrA1和dfrA12几乎仅在系统发育组A和B1的菌株中发现；并且存在于动物和人类粪便分离株中。相比之下，dfrA17在粪便和尿液分离株中均有发现，且包含所有系统发育组的菌株。无论标本来源和系统发育组状态如何，sul1和sul2基因在分离株中的流行程度相同。对具有相同盒基因的分离株进行脉冲场凝胶电泳分析表明，它们在基因上具有多样性。
携带1类整合子的动物粪便分离株比人类粪便和人类尿液分离株更多，并且系统发育组的分布在动物和人类粪便分离株中较为常见，但与人类尿液分离株不同。
来自产食动物的共生分离株是携带抗生素抗性基因的整合子的重要储存库。
