Longitudinal characterization of antimicrobial resistance genes in feces shed from cattle fed different subtherapeutic antibiotics
Longitudinal characterization of antimicrobial resistance genes in feces shed from cattle fed different subtherapeutic antibiotics
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DOI：
10.1186/1471-2180-11-19
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发表时间：
2011-01-24
期刊：
影响因子：
4.2
通讯作者：
McAllister, Tim A.
中科院分区：
文献类型：
--
作者：
Alexander, Trevor W.;Yanke, Jay L.;McAllister, Tim A.
背景资料：源自牲畜的耐抗生素细菌和耐药基因决定因素的环境传播受到其在农业相关基质中持久存在的影响。本研究调查了给肉牛施用亚治疗浓度的抗菌剂对粪便沉积物微生物群落中耐药基因的丰度和持久性的影响。牛（每次给药3个畜栏，每个畜栏10头牛）接受金霉素、金霉素+磺胺二甲嘧啶、泰乐菌素给药或不接受抗菌剂给药（对照）。通过将来自每个畜栏的新鲜粪便混合到单个复合样品中来制备模型粪便沉积物（n = 3）。实时荧光定量PCR法测定了175天环境暴露后复合材料DNA中泰特、sul和p53抗性基因的浓度。通过定量和变性梯度凝胶电泳（DGGE）的PCR扩增的16 S-rRNA。结果：粪便中的16 S-rRNA的浓度是相似的治疗，并增加了第56天，之后下降。16 S-rRNA的DGGE图谱在不同的治疗和时间，说明微生物群落的时间变化。175天后，粪便中所有测定的耐药基因决定簇均可定量。抗菌治疗差异影响某些耐药基因的丰度，但一般不影响其持久性。在前56天内，泰特（B）、泰特（C）、sul 1、sul 2、tetin（A）的浓度呈增加趋势，之后下降，而泰特（M）和泰特（W）在175天内逐渐下降。在第7天，浓度的β-内酰胺酶（X）是最大的粪便从牛喂泰乐菌素，相比所有其他treatment.Conclusion：丰富的基因编码的抗菌药物耐药性牛粪便中的饲料中的抗生素的影响。抗性基因可以在牛的粪便中持续存在超过175天，一些基因的浓度随着时间的推移而增加。加速DNA降解的管理做法，如频繁的土地应用或堆肥的粪便可能会减少牛粪便作为抗菌素耐药性的水库的程度。
Background: Environmental transmission of antimicrobial-resistant bacteria and resistance gene determinants originating from livestock is affected by their persistence in agricultural-related matrices. This study investigated the effects of administering subtherapeutic concentrations of antimicrobials to beef cattle on the abundance and persistence of resistance genes within the microbial community of fecal deposits. Cattle (three pens per treatment, 10 steers per pen) were administered chlortetracycline, chlortetracycline plus sulfamethazine, tylosin, or no antimicrobials (control). Model fecal deposits (n = 3) were prepared by mixing fresh feces from each pen into a single composite sample. Real-time PCR was used to measure concentrations of tet, sul and erm resistance genes in DNA extracted from composites over 175 days of environmental exposure in the field. The microbial communities were analyzed by quantification and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S-rRNA.Results: The concentrations of 16S-rRNA in feces were similar across treatments and increased by day 56, declining thereafter. DGGE profiles of 16S-rRNA differed amongst treatments and with time, illustrating temporal shifts in microbial communities. All measured resistance gene determinants were quantifiable in feces after 175 days. Antimicrobial treatment differentially affected the abundance of certain resistance genes but generally not their persistence. In the first 56 days, concentrations of tet(B), tet(C), sul1, sul2, erm(A) tended to increase, and decline thereafter, whereas tet(M) and tet(W) gradually declined over 175 days. At day 7, the concentration of erm(X) was greatest in feces from cattle fed tylosin, compared to all other treatments.Conclusion: The abundance of genes coding for antimicrobial resistance in bovine feces can be affected by inclusion of antibiotics in the feed. Resistance genes can persist in feces from cattle beyond 175 days with concentrations of some genes increasing with time. Management practices that accelerate DNA degradation such as frequent land application or composting of manure may reduce the extent to which bovine feces serves as a reservoir of antimicrobial resistance.