Department of Microbiology and Infectious Diseases, Toho University, Japan.
Microbes Environ. 2013;28(1):81-6. doi: 10.1264/jsme2.me12137. Epub 2012 Nov 9.
Antimicrobial growth promoters (AGPs) have been banned and phased out because their use has been linked to the emergence and spread of antibiotic-resistant pathogens; however, the ban has had a marked impact on livestock production, and feed additive alternatives to AGPs are required. We focused on green tea leaves as potential alternatives to AGPs because they contain significant amounts of polyphenol catechins, which have antivirus and antimicrobial effects. We examined cross-resistance between epigallocatechin gallate (EGCG), which is the most abundant catechin of green tea leaves, and commercially available antimicrobials in clinically problematic antimicrobial-resistant bacteria, and whether bacteria have the ability to acquire resistance by consecutive passage in sub-inhibitory concentrations of EGCG. EGCG did not display any cross-resistance with reference antimicrobials and the bacteria did not acquire EGCG resistance. Further, we examined the growth-promoting effects of dried green tea leaves on the breeding of a new Japanese breed, Tokyo-X pigs. While the mortality rates of the green tea leaf (GTL) and AGP groups were both 11.1% (one in nine piglets), the mortality rate was 50% for the control group with an additive-free diet (four in eight piglets). The rate of body weight increase in both the GTL and AGP groups was approximately the same. The growth-promoting effects of green tea leaves and AGPs were similar, and there was no possibility that the antimicrobial properties of catechins caused the same problem as AGPs. Thus, it can be concluded that green tea leaves are a safe feed additive alternative to AGPs.
抗菌生长促进剂（AGP）已被禁止和逐步淘汰，因为它们的使用与抗生素耐药病原体的出现和传播有关；然而，该禁令对畜牧业生产产生了显著影响，需要寻找 AGP 的饲料添加剂替代品。我们专注于绿茶作为 AGP 的潜在替代品，因为它们含有大量的多酚儿茶素，具有抗病毒和抗菌作用。我们研究了表没食子儿茶素没食子酸酯（EGCG）与临床上有问题的抗微生物耐药细菌中市售抗微生物药物之间的交叉耐药性，以及细菌是否具有在亚抑菌浓度的 EGCG 中连续传代获得耐药性的能力。EGCG 与参考抗微生物药物没有显示任何交叉耐药性，细菌也没有获得 EGCG 耐药性。此外，我们研究了干绿茶对新型日本猪品种东京 X 猪繁殖的促进生长作用。虽然绿茶（GTL）和 AGP 组的死亡率均为 11.1%（每 9 头仔猪中有 1 头），但在无添加剂饮食的对照组中，死亡率为 50%（每 8 头仔猪中有 4 头）。GTL 和 AGP 组的体重增加率大致相同。绿茶和 AGP 的促生长作用相似，儿茶素的抗菌特性不可能引起与 AGP 相同的问题。因此，可以得出结论，绿茶是 AGP 的安全饲料添加剂替代品。
