Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
Microb Ecol. 2010 May;59(4):678-88. doi: 10.1007/s00248-009-9625-6. Epub 2010 Jan 15.
From July to December 2006, a panel of 401 enterococci was isolated from carcass rinse samples collected in five poultry processing plants in New Zealand. Agar diffusion assays for nine antibacterial drugs were used to obtain a resistance phenotype for each isolate. Hierarchical clustering techniques and diversity indices showed a high diversity of resistance phenotypes within each plant, with populations of Enterococcus faecalis showing greater heterogeneity than Enterococcus faecium. Bayesian modelling identified three clusters of phenotype patterns within the panel: the E. faecium isolates showed a high probability of containing two distinct clusters, whilst the E. faecalis isolates all grouped together to form the third cluster. The validity of these three clusters was examined using pairwise fixation indices and analysis of variance. Comparing the three clusters to the structure of the participating companies showed that resistance phenotypes for E. faecium isolated from processing plants that were geographically separated but were operated by the same integrated poultry company were more similar than E. faecium isolated from unconnected companies. Company-level management factors, such as the routine use of antibacterial drugs and the genetic line of birds reared, mirrored the structure of these clusters, thus indicating that company-level factors were the dominant selective pressures upon resistance phenotypes across all operating units within these integrated poultry companies.
2006 年 7 月至 12 月，从新西兰五个家禽加工厂采集的胴体冲洗样本中分离出 401 株肠球菌。琼脂扩散法检测了 9 种抗菌药物，以获得每个分离株的耐药表型。层次聚类技术和多样性指数显示，每个工厂内的耐药表型多样性很高，粪肠球菌种群的异质性大于屎肠球菌。贝叶斯模型确定了该组中存在三个表型模式群：屎肠球菌分离株极有可能包含两个不同的群，而粪肠球菌分离株全部聚集在一起形成第三个群。使用成对固定指数和方差分析检验了这三个群的有效性。将这三个群与参与公司的结构进行比较表明，来自地理位置分开但由同一综合家禽公司运营的加工厂的肠球菌与来自不相关公司的肠球菌相比，其分离株具有更高的相似性。公司层面的管理因素，如抗菌药物的常规使用和饲养的禽鸟遗传系，反映了这些群的结构，这表明公司层面的因素是这些综合家禽公司所有运营单位内耐药表型的主要选择压力。
