Agersø Yvonne, Sandvang Dorthe
Danish Food and Veterinary Research, Section of Antimicrobial Resistance, Bulowsvej 27, 1790 Copenhagen V, Denmark.
Appl Environ Microbiol. 2005 Dec;71(12):7941-7. doi: 10.1128/AEM.71.12.7941-7947.2005.
The presence of tetracycline resistance (Tc(r)) genes and class I integrons (in-1), and their ability to cotransfer were investigated in Tc(r) gram-negative (185 strains) and gram-positive (72 strains) bacteria from Danish farmland and pigsties. The isolates belonged to the groups or species Escherichia coli, Enterobacter spp., Arthrobacter spp., Alcaligenes spp., Pseudomonas spp., and Corynebacterium glutamicum. The 257 isolates were screened for in-1. Eighty-one of the gram-negative isolates were also screened for the Tc(r) genes tet(A), tet(B), and tet(C), and all (n = 72) gram-positive isolates were screened for tet(33). Fourteen (7%) of the soil isolates and eleven (25%) of the pigsty isolates contained in-1. All isolates that contained tet genes also contained in-1, except one gram-negative isolate from a pigsty that contained tet(B). All gram-positive isolates with in-1 also contained tet(33). No isolates contained more than one tet gene. The in-1-positive isolates were tested for resistance to selected antimicrobial agents and showed resistance to three to nine drugs. Filter-mating experiments showed cotransfer of Tc(r) and class I integrons from soil isolates to Escherichia coli and/or Pseudomonas putida. We conclude that soil bacteria in close contact to manure or pigsty environment may thus have an important role in horizontal spread of resistance. Use of tetracyclines in food animal production may increase not only Tc(r) but also multidrug resistance (caused by the presence tet genes and in-1) in bacteria.
对来自丹麦农田和猪圈的革兰氏阴性（185株）和革兰氏阳性（72株）四环素抗性（Tc(r)）细菌中的四环素抗性（Tc(r)）基因和I类整合子（in-1）及其共转移能力进行了研究。分离株属于大肠杆菌、肠杆菌属、节杆菌属、产碱菌属、假单胞菌属和谷氨酸棒杆菌等组或种。对257株分离株进行了in-1筛选。对81株革兰氏阴性分离株还进行了Tc(r)基因tet(A)、tet(B)和tet(C)的筛选，对所有（n = 72）革兰氏阳性分离株进行了tet(33)的筛选。14株（7%）土壤分离株和11株（25%）猪圈分离株含有in-1。所有含有tet基因的分离株也都含有in-1，但有一株来自猪圈的革兰氏阴性分离株含有tet(B)除外。所有含有in-1的革兰氏阳性分离株也都含有tet(33)。没有分离株含有超过一个tet基因。对in-1阳性分离株进行了对选定抗菌药物的抗性测试，结果显示它们对三到九种药物具有抗性。滤膜杂交实验表明，Tc(r)和I类整合子可从土壤分离株共转移至大肠杆菌和/或恶臭假单胞菌。我们得出结论，与粪便或猪圈环境密切接触的土壤细菌可能在抗性的水平传播中起重要作用。在食用动物生产中使用四环素不仅可能增加细菌中的Tc(r)，还可能增加多药抗性（由tet基因和in-1的存在引起）。
