Lapierre Lisette, Cornejo Javiera, Borie Consuelo, Toro Cecilia, San Martín Betty
Laboratory of Veterinary Pharmacology, College of Veterinary Science, Universidad de Chile, Avenida Santa Rosa, La Pintana, Santiago, Chile.
Microb Drug Resist. 2008 Dec;14(4):265-72. doi: 10.1089/mdr.2008.0810.
The aim of this research was to identify the presence of integrons among Escherichia coli strains isolated from poultry and swine and to characterize the topological association of these integrons with resistance genes and assess their potential ability to transfer these elements by conjugation. One hundred and seventy-two strains of E. coli were isolated. Their resistance to tetracycline, streptomycin, sulfamethoxazole-trimethoprim, ciprofloxacin, and enrofloxacin was studied by plate dilution. In resistant strains the presence of integrons and resistance genes was assessed by PCR. In the variable region, genes aadA1, dfrA1, and qnr were analyzed. Also, presence of tetA, tetB, and sul1 was assessed. Transference of these genes and integrons in vitro was evaluated by conjugation assays, using E. coli J53 Az(r) as recipient strain. Seventy-eight percent and 83% of the poultry and swine strains, respectively, were resistant to at least one of the studied antimicrobials. Of the isolated strains 91 presented integrons. Resistance genes detected within the integrons were aadA1, dfrA1, and sat1. Gene qnr was not detected. Genes tet and sul1 were identified in 105 and 53 strains, respectively. Seven strains transferred their resistance determinants by conjugation. The results verify the high percentage of antibiotic resistance in the E. coli strains isolated, and these represent a reservoir of resistance genes and integrons.
本研究的目的是鉴定从家禽和猪中分离出的大肠杆菌菌株中整合子的存在情况，表征这些整合子与耐药基因的拓扑关联，并评估它们通过接合转移这些元件的潜在能力。分离出172株大肠杆菌。通过平板稀释法研究了它们对四环素、链霉素、磺胺甲恶唑-甲氧苄啶、环丙沙星和恩诺沙星的耐药性。在耐药菌株中，通过聚合酶链反应（PCR）评估整合子和耐药基因的存在情况。在可变区，分析了aadA1、dfrA1和qnr基因。此外，还评估了tetA、tetB和sul1的存在情况。以大肠杆菌J53 Az(r)作为受体菌株，通过接合试验评估这些基因和整合子在体外的转移情况。分别有78%的家禽菌株和83%的猪菌株对至少一种所研究的抗菌药物耐药。在所分离的菌株中，91株存在整合子。在整合子中检测到的耐药基因是aadA1、dfrA1和sat1。未检测到qnr基因。分别在105株和53株菌株中鉴定出tet和sul1基因。7株菌株通过接合转移了它们的耐药决定簇。结果证实了所分离的大肠杆菌菌株中抗生素耐药性的高比例，并且这些菌株代表了耐药基因和整合子的储存库。
