Duriez Patrick, Topp Edward
Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario, Canada N5V 4T3.
Appl Environ Microbiol. 2007 Sep;73(17):5486-93. doi: 10.1128/AEM.00218-07. Epub 2007 Jul 6.
Many confined-livestock farms store their wastes for several months prior to use as a fertilizer. Storing manure for extended periods could significantly bias the composition of enteric bacterial populations subsequently released into the environment. Here, we compared populations of Escherichia coli isolated from fresh feces and from the manure-holding tank (stored manure) of a commercial swine farm, each sampled monthly for 6 months. The 4,668 confirmed E. coli isolates were evaluated for resistance to amikacin, ampicillin, cephalothin, chloramphenicol, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, trimethoprim, and trimethoprim plus sulfamethoxazole. A subset of 1,687 isolates was fingerprinted by repetitive extragenic palindromic PCR (rep-PCR) with the BOXA1R primer to evaluate the diversity and the population structure of the collection. The population in the stored manure was generally more diverse than that in the fresh feces. Half of the genotypes detected in the stored manure were never detected in the fresh fecal material, and only 16% were detected only in the fresh feces. But the majority of the isolates (84%) were assigned to the 34% of genotypes shared between the two environments. The structure of the E. coli population showed important monthly variations both in the extent and distribution of the diversity of the observed genotypes. The frequency of detection of resistance to specific antibiotics was not significantly different between the two collections and varied importantly between monthly samples. Resistance to multiple antibiotics was much more temporally dynamic in the fresh feces than in the stored manure. There was no relationship between the distribution of rep-PCR fingerprints and the distribution of antibiotic resistance profiles, suggesting that specific antibiotic resistance determinants were dynamically distributed within the population.
许多集约化养殖场在将粪便用作肥料之前会储存数月。长时间储存粪便可能会显著影响随后释放到环境中的肠道细菌种群组成。在此，我们比较了从商业养猪场的新鲜粪便和储粪池（储存的粪便）中分离出的大肠杆菌种群，每个样本每月采集一次，共采集6个月。对4668株经确认的大肠杆菌分离株进行了对阿米卡星、氨苄西林、头孢噻吩、氯霉素、卡那霉素、萘啶酸、链霉素、磺胺甲恶唑、四环素、甲氧苄啶以及甲氧苄啶加磺胺甲恶唑的耐药性评估。使用BOXA1R引物通过重复外显子回文PCR（rep-PCR）对1687株分离株的一个子集进行指纹图谱分析，以评估该集合的多样性和种群结构。储存粪便中的种群通常比新鲜粪便中的种群更加多样化。在储存粪便中检测到的基因型有一半在新鲜粪便中从未检测到，只有16%仅在新鲜粪便中被检测到。但大多数分离株（84%）属于两种环境中共有的34%的基因型。大肠杆菌种群结构在观察到的基因型多样性的程度和分布方面都显示出重要的月度变化。两个样本集中对特定抗生素的耐药性检测频率没有显著差异，且月度样本之间差异很大。新鲜粪便中对多种抗生素的耐药性在时间上比储存粪便中的变化更大。rep-PCR指纹图谱的分布与抗生素耐药性谱的分布之间没有关系，这表明特定的抗生素耐药决定因素在种群中是动态分布的。
