Jahne Michael A, Rogers Shane W, Ramler Ivan P, Holder Edith, Hayes Gina
Institute for a Sustainable Environment, Clarkson University, Potsdam, NY, 13699, USA.
Environ Monit Assess. 2015 Jan;187(1):4168. doi: 10.1007/s10661-014-4168-9. Epub 2014 Dec 12.
Forty-two percent of Escherichia coli and 58% of Enterococcus spp. isolated from cattle feedlot runoff and associated infiltration basin and constructed wetland treatment system were resistant to at least one antibiotic of clinical importance; a high level of multidrug resistance (22% of E. coli and 37% of Enterococcus spp.) was observed. Hierarchical clustering revealed a closely associated resistance cluster among drug-resistant E. coli isolates that included cephalosporins (ceftiofur, cefoxitin, and ceftriaxone), aminoglycosides (gentamycin, kanamycin, and amikacin), and quinolone nalidixic acid; antibiotics from these classes were used at the study site, and cross-resistance may be associated with transferrable multiple-resistance elements. For Enterococcus spp., co-resistance among vancomycin, linezolid, and daptomycin was common; these antibiotics are reserved for complicated clinical infections and have not been approved for animal use. Vancomycin resistance (n = 49) only occurred when isolates were resistant to linezolid, daptomycin, and all four of the MLSB (macrolide-lincosamide-streptogramin B) antibiotics tested (tylosin, erythromycin, lincomycin, and quinipristin/dalfopristin). This suggests that developing co-resistance to MLSB antibiotics along with cyclic lipopeptides and oxazolidinones may result in resistance to vancomycin as well. Effects of the treatment system on antibiotic resistance were pronounced during periods of no rainfall and low flow (long residence time). Increased hydraulic loading (short residence time) under the influence of rain caused antibiotic-resistant bacteria to be flushed through the treatment system. This presents concern for environmental discharge of multidrug-resistant organisms relevant to public health.
从肉牛饲养场径流以及相关渗滤池和人工湿地处理系统分离出的大肠杆菌中有42%、肠球菌中有58%对至少一种具有临床重要性的抗生素耐药；观察到高水平的多重耐药情况（大肠杆菌中有22%，肠球菌中有37%）。层次聚类分析显示，耐药大肠杆菌分离株之间存在一个紧密相关的耐药簇，其中包括头孢菌素（头孢噻呋、头孢西丁和头孢曲松）、氨基糖苷类（庆大霉素、卡那霉素和阿米卡星）以及喹诺酮萘啶酸；研究地点使用了这些类别的抗生素，交叉耐药可能与可转移的多重耐药元件有关。对于肠球菌，万古霉素、利奈唑胺和达托霉素之间的共同耐药很常见；这些抗生素用于治疗复杂的临床感染，尚未获批用于动物。仅当分离株对利奈唑胺、达托霉素以及所测试的所有四种大环内酯 - 林可酰胺 - 链阳霉素B（MLSB）类抗生素（泰乐菌素、红霉素、林可霉素和奎奴普丁/达福普汀）耐药时才会出现万古霉素耐药（n = 49）。这表明，对MLSB类抗生素以及环脂肽和恶唑烷酮产生共同耐药可能会导致对万古霉素也产生耐药。在无降雨和低流量时期（停留时间长），处理系统对抗生素耐药性的影响较为显著。降雨影响下增加的水力负荷（停留时间短）导致耐药细菌被冲出处理系统。这引发了对与公共卫生相关的多重耐药生物环境排放的担忧。
