Finnish Food Safety Authority Evira, Mustialankatu 3, FI-00790 Helsinki, Finland.
Poult Sci. 2013 Jan;92(1):250-4. doi: 10.3382/ps.2012-02575.
Extended-spectrum β-lactamases (ESBL) and class C serine β-lactamases (pAmpC) able to hydrolyze third-generation cephalosporins are a recognized threat to the efficacy of these drugs in treating serious infections. Broiler chicks are a known source of Escherichia coli harboring genes for these enzymes. Competitive exclusion (CE) has been used for decades in Finland to prevent the colonization of broiler ceca by Salmonella, but has not been widely used in Sweden. The markedly different prevalences of ESBL- or pAmpC-producing E. coli at slaughter in broilers produced in the 2 countries suggest a potential role for CE. The present study was undertaken to determine the efficacy of a commercial CE product in reducing the colonization of broiler ceca by ESBL- or pAmpC-producing E. coli. The challenge organisms were isolated from healthy broilers in Sweden. Each E. coli strain (1 ESBL and 2 pAmpC types) was subjected to 4 replicate trials. In each trial, a group of 20 newly hatched Ross breed chicks were treated by gavage with the CE product, whereas another group of 20 was left untreated. The next day, all 40 chicks were inoculated by gavage with the E. coli strain. The chicks were reared in cardboard boxes and received feed and water ad libitum. After a week the chicks were asphyxiated with CO(2), and their ceca removed and examined for the presence of the E. coli strains. The median and quartiles of the challenge E. coli estimates in the groups were determined, and the treated and control groups were compared with the Wilcoxon 2-sample test. In each trial, a substantial and statistically significant or highly significant reduction was observed in the colonization of the ceca of CE-treated chicks by E. coli strains, compared with that of untreated control. Referring to an arbitrary criterion for high shedders presented in the literature, it was concluded that at least for the ESBL E. coli, the results were also of epidemiological relevance.
产Extended-spectrum β-lactamases（ESBL）和 Class C serine β-lactamases（pAmpC）的大肠杆菌能够水解第三代头孢菌素，这对这些药物治疗严重感染的疗效构成了公认的威胁。肉鸡是携带这些酶基因的大肠杆菌的已知来源。竞争排斥（CE）在芬兰已使用了数十年，以防止沙门氏菌在肉鸡盲肠中定植，但在瑞典并未广泛使用。这两个国家在屠宰肉鸡中 ESBL 或 pAmpC 产生的大肠杆菌的流行率存在显著差异，这表明 CE 可能发挥了作用。本研究旨在确定一种商业 CE 产品在减少 ESBL 或 pAmpC 产生的大肠杆菌定植肉鸡盲肠中的效果。挑战菌是从瑞典健康肉鸡中分离出来的。每个大肠杆菌菌株（1 株 ESBL 和 2 株 pAmpC 型）进行了 4 次重复试验。在每次试验中，一组 20 只新孵化的 Ross 品种小鸡通过灌胃接受 CE 产品治疗，而另一组 20 只小鸡不接受治疗。第二天，所有 40 只小鸡都通过灌胃接种了大肠杆菌菌株。小鸡在纸箱中饲养，自由采食饲料和水。一周后，小鸡被 CO2 窒息，取出盲肠并检查大肠杆菌菌株的存在情况。确定了处理组和对照组中挑战大肠杆菌估计值的中位数和四分位数，并使用 Wilcoxon 2 样本检验对两组进行比较。在每次试验中，与未处理的对照组相比，CE 处理组的小鸡盲肠中大肠杆菌菌株的定植量显著减少，而且具有统计学意义或高度显著。参考文献中提出的高脱落者的任意标准，可以得出结论，至少对于 ESBL 大肠杆菌，结果也具有流行病学意义。
