BACTERIAL ANTIBIOTIC RESISTANCE IN AGRICULTURE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。细菌抗生素耐药性的出现是一个严重的公共卫生问题，因为它危及传染病的治疗。为了避免这个问题，我们必须了解抗生素耐药性的程度。我们在广泛使用四环素类抗生素的奶牛场土壤中发现了多重耐药细菌。核心假设是，奶牛场土壤中含有耐多药细菌，或者已知的调节剂诱导了耐多药。这一假设的基本原理是，一旦了解了农业中固有的和可诱导的细菌多药耐药性有多普遍，就有可能采取措施减少抗生素功效有限的问题。为了研究这一点(1)，我们从新墨西哥州罗斯福县的当地奶牛场分离并鉴定了肠道土壤细菌，确定了对氯霉素、萘啶酸、青霉素G和四环素等与mar相关的抗生素的耐药性。我们纯化了质粒DNA并对其表型活性进行了表征。菌株对抗生素的最低抑菌浓度（mic）在6 ~ 50 ？g/mL氯霉素，2-8 ？钠二酸25- 300 ？g/mL为青霉素g和1- 80 ？四环素为g/mL。在水杨酸存在的情况下，许多分离株对同一种抗生素的mic显著增强。从随机抽取的菌株中提取的质粒DNA对氯霉素和青霉素g具有耐药性。我们得出结论，来自奶牛场表土的肠道细菌具有多重耐药和耐药质粒。我们认为乳制品表土对土壤传播的人畜共患病很重要，因此暗示这种环境是细菌对临床相关抗生素耐药的储存库。1. J. M. Burgos， B. A. Ellington和M. F. Varela. 2005。奶牛场表土中多重耐药肠道细菌的存在。[j] .乳品科学，88(8):1391-1398。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The emergence of bacterial antibiotic resistance is a serious public health concern as it compromises treatment of infectious disease. To circumvent this problem, we have to understand the extent of antibiotic resistance. We have found multi-drug resistant bacteria in dairy farm soil, where tetracycline antibiotics are widely used. The central hypothesis is that dairy farm soil harbors multidrug resistant bacteria or that known modulators induce multidrug resistance. The rationale for the hypothesis is that once it is known how widespread intrinsic and inducible bacterial multidrug resistances are in agriculture, it will be possible to invoke measures to reduce the problem of the limited efficacy of antibiotics. To study this (1), we isolated and identified enteric soil bacteria from local dairy farms within Roosevelt County, NM, determined the resistance profiles to antibiotics associated with mar, such as chloramphenicol, nalidixic acid, penicillin G and tetracycline. We purified plasmid DNA and characterized mar phenotypic activity. The minimal inhibitory concentrations (MICs) of antibiotics for the isolates ranged between 6 - 50 ?g/mL for chloramphenicol, 2-8 ?g/mL for nalidixic acid, 25- 300 ?g/mL for penicillin G and 1- 80 ?g/mL for tetracycline. Many of the isolates had significantly enhanced MICs for the same antibiotics in the presence of salycilate. Plasmid DNA extracted from randomly chosen isolates conferred resistances to chloramphenicol and penicillin G. We conclude that enteric bacteria from dairy farm topsoil are multi-drug resistant and harbor antibiotic resistance plasmids. We suggest dairy topsoil is important for soil-borne zoonosis, thus implicating this environment as a reservoir for bacterial resistance against clinically relevant antibiotics. 1. Burgos, J. M., B. A. Ellington, and M. F. Varela. 2005. Presence of Multidrug-Resistant Enteric Bacteria in Dairy Farm Topsoil. J. Dairy Sci. 88:1391-1398.