BACTERIAL ANTIBIOTIC RESISTANCE IN AGRICULTURE

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。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。为了解决这个问题，我们必须了解抗生素耐药性的程度。在四环素类抗生素广泛使用的奶牛场土壤中，我们发现了多重耐药细菌。中心假设是奶牛场土壤窝藏多重耐药细菌或已知的调制器诱导多重耐药。这一假设的基本原理是，一旦了解了内在和诱导细菌多药耐药性在农业中的广泛程度，就有可能采取措施来减少抗生素疗效有限的问题。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，确定了对与mar相关的抗生素（如氯霉素、萘啶酸、青霉素G和四环素）的耐药性。我们纯化了质粒DNA并表征了mar表型活性。最低抑菌浓度（MIC）的抗生素的分离株范围在6 - 50？g/mL，氯霉素2-8？25- 300 μ g/mL萘啶酸; g/mL青霉素G和1- 80？g/mL四环素。在水杨酸盐存在下，许多分离株对相同抗生素的MIC显著增强。从随机选择的菌株中提取的质粒DNA赋予氯霉素和青霉素G抗性。因此，奶牛场表层土壤中的肠道细菌具有多重耐药性，并携带抗生素耐药质粒。我们认为，乳制品表土是重要的土传人畜共患病，从而暗示这种环境作为一个水库的细菌耐药性对临床相关的抗生素。 1.布尔戈斯，J.M.，B。A. Ellington和M. F.瓦雷拉2005.奶牛场表层土壤中多重耐药肠道细菌的存在。J. Dairy Sci. 88：1391-1398。

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.