Department of Food and Animal Biotechnology, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
Center for Food Bioconvergence, Seoul National University, Seoul, Republic of Korea.
Microbiol Spectr. 2021 Dec 22;9(3):e0170321. doi: 10.1128/Spectrum.01703-21. Epub 2021 Dec 15.
Selective media using antimicrobial supplements generate unique microbial ecology to facilitate bacterial isolation. However, antibiotic-resistant bacteria indigenous to samples can interfere with the isolation process using selective media. Recent studies showed that extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is highly prevalent on retail raw chicken and compromises the efficacy of Campylobacter isolation because ESBL-producing E. coli are resistant to antimicrobial supplements in Campylobacter-selective media and outgrows Campylobacter. The objective of this study was to improve Campylobacter isolation by inhibiting the growth of ESBL-producing E. coli using bacteriophages (phages). The supplementation of Campylobacter-selective media with E. coli phages reduced the level of ESBL-producing E. coli during the enrichment step. When E. coli phages were combined with the antimicrobial supplements of Campylobacter-selective media, antimicrobial synergy was observed, particularly with rifampicin, an antibiotic used in Preston medium. Although the same materials (i.e., phages and selective media) were used, the sequence of combining the materials markedly influenced the inhibition of ESBL-producing E. coli and the isolation of Campylobacter. These findings indicated that the modulation of microbial competition at the enrichment step was critical to the successful isolation of fastidious bacteria and that phages can be utilized to facilitate the selective enrichment of target bacteria by inhibiting their competitive bacteria. Phages are promising antimicrobial alternatives. In this study, we first demonstrated that phages can be used to facilitate selective isolation of fastidious bacteria that are prone to be outgrown by bacterial competitors during isolation. The effectiveness of a phage-based isolation method was primarily dependent on the antimicrobial synergy between phages and antibiotics used in selective media. The same approach could be applied to the development of isolation methods for other fastidious bacteria.
选择使用抗菌添加剂的培养基会产生独特的微生物生态系统，从而促进细菌的分离。然而，样品中固有的抗生素耐药菌会干扰使用选择性培养基进行的分离过程。最近的研究表明，零售生鸡肉中广泛存在产生超广谱β-内酰胺酶（ESBL）的大肠杆菌，这会降低弯曲菌分离的效果，因为 ESBL 产生的大肠杆菌对弯曲菌选择性培养基中的抗菌添加剂具有耐药性，并在数量上超过了弯曲菌。本研究的目的是通过使用噬菌体（phages）抑制 ESBL 产生的大肠杆菌的生长来提高弯曲菌的分离率。在选择性培养基中添加大肠杆菌噬菌体可减少富集步骤中 ESBL 产生的大肠杆菌的水平。当将大肠杆菌噬菌体与弯曲菌选择性培养基的抗菌添加剂结合使用时，观察到了抗菌协同作用，特别是与用于 Preston 培养基的抗生素 rifampicin。尽管使用了相同的材料（即噬菌体和选择性培养基），但组合材料的顺序对抑制 ESBL 产生的大肠杆菌和弯曲菌的分离有显著影响。这些发现表明，在富集步骤中调节微生物竞争对于成功分离难养细菌至关重要，并且噬菌体可用于通过抑制其竞争细菌来促进目标细菌的选择性富集。噬菌体是有前途的抗菌替代品。在本研究中，我们首次证明噬菌体可用于促进易被竞争细菌在分离过程中过度生长的难养细菌的选择性分离。基于噬菌体的分离方法的有效性主要取决于噬菌体与选择性培养基中使用的抗生素之间的抗菌协同作用。相同的方法可应用于开发其他难养细菌的分离方法。
