Department of Animal Science, The University of Tennessee, Knoxville, TN 37996-4574, USA.
J Appl Microbiol. 2011 Dec;111(6):1544-50. doi: 10.1111/j.1365-2672.2011.05163.x. Epub 2011 Oct 31.
Several bacteriocins (BCNs) that were identified from chicken commensal bacteria dramatically reduced Campylobacter colonization in poultry and are being directed toward on-farm control of this important foodborne human pathogen. A recent study has shown that BCN resistance in Campylobacter jejuni is very difficult to develop in vitro. In this study, in vivo development and stability of BCN resistance in Campylobacter was examined.
Chickens infected with Camp. jejuni NCTC 11168 were treated with BCN E-760 at the dose of 5 mg kg(-1) body weight day(-1) via oral gavages for three consecutive days, which selected BCN-resistant (BCN(r)) mutants in the treated birds. However, all the in vivo-selected mutants only displayed low levels of resistance to BCN (MIC = 2-8 mg l(-1)) when compared to parent strain (MIC = 0.5 mg l(-1)). Inactivation of CmeABC efflux pump of the BCN(r) mutants led to increased susceptibility to BCN (8-32 fold MIC reduction). Three different BCN(r) Campylobacter strains (in vitro- or in vivo-derived) were examined for the stability of BCN resistance using both in vitro and in vivo systems. The low level of BCN resistance in these strains was not stable in vitro or in vivo in the absence of BCN selection pressure.
Usage of BCN E-760 only selected low-level BCN(r) Camp. jejuni mutants in vivo, and the low-level BCN resistance was not stable in vitro and in vivo.
The study provides helpful information for risk assessment of the future practical application of the anti-Campylobacter BCNs in animals.
从鸡共生菌中鉴定出的几种细菌素（BCN）可显著减少家禽中的弯曲杆菌定植，并正在针对这种重要的食源性病原体进行农场控制。最近的一项研究表明，鸡空肠弯曲杆菌中 BCN 耐药性在体外很难发展。本研究检测了弯曲杆菌中 BCN 耐药性的体内发展和稳定性。
用 BCN E-760 通过口服灌胃连续 3 天以 5mgkg(-1)体重剂量处理感染空肠弯曲杆菌 NCTC 11168 的鸡，在处理的鸟类中选择 BCN 耐药（BCN(r)）突变体。然而，与亲本菌株（MIC=0.5mgL(-1)）相比，所有体内选择的突变体仅显示出对 BCN 的低水平耐药性（MIC=2-8mgL(-1)）。CmeABC 外排泵失活导致 BCN(r)突变体对 BCN 的敏感性增加（MIC 降低 8-32 倍）。使用体外和体内系统研究了三种不同的 BCN(r)弯曲杆菌菌株（体外或体内衍生）对 BCN 耐药性的稳定性。在没有 BCN 选择压力的情况下，这些菌株中的低水平 BCN 耐药性在体外或体内均不稳定。
BCN E-760 的使用仅在体内选择了低水平的 BCN(r)空肠弯曲杆菌突变体，并且低水平的 BCN 耐药性在体外和体内均不稳定。
该研究为未来在动物中实际应用抗弯曲杆菌 BCN 进行风险评估提供了有价值的信息。
