Food Safety Programme, ESR Ltd, Christchurch Science Centre, PO Box 29-181, Ilam, Christchurch 8540, New Zealand.
Food Microbiol. 2013 Oct;36(1):14-21. doi: 10.1016/j.fm.2013.03.006. Epub 2013 Apr 10.
A number of outbreaks of Escherichia coli O157:H7 infections involving beef have been reported. Options for controlling bacterial pathogens in raw foods are limited, but one is to use bacteriophages (phages). We describe the isolation and characterisation of phage FAHEc1, which infects E. coli O157, and its ability to kill its host in vitro and on beef. The phage belonged to the family Myoviridae and lysed 28 of 30 E. coli O157 (:H7, :HNM and :H not specified) isolates, only one other non-O157 E. coli serotype (O162:H7), and none of the other 13 bacterial species tested. The phage did not contain stx1, stx2, eae or ehxA virulence genes as assessed by PCR. An approximate 4 log₁₀ inactivation of E. coli O157:H7 occurred at 5 °C in the presence of phage FAHEc1 at >10⁷ PFU/ml in broth in vitro. On thinly sliced beef pieces incubated at 37 °C, a > 2.7 log₁₀ reduction occurred with 3.2 × 10⁷ PFU/4 cm² meat piece. At lower phage concentrations (10³-10⁴ PFU/4 cm² piece) phage replication occurred on beef at 37 °C. When the phage was applied to beef pieces under conditions simulating hot boning and conventional carcass cooling, inactivation of E. coli O157:H7 of approximately 2 log₁₀ was measured under optimal conditions with phages applied at 3.2 × 10⁷ PFU/4 cm² meat piece.
已报告了多起因食用牛肉而引发的大肠杆菌 O157:H7 感染疫情。控制生食品中细菌病原体的选择有限，但其中之一是使用噬菌体（phages）。我们描述了一种感染大肠杆菌 O157 的噬菌体 FAHEc1 的分离和特性，以及其在体外和牛肉上杀死宿主的能力。该噬菌体属于肌尾噬菌体科，可裂解 30 个大肠杆菌 O157（:H7、:HNM 和 :H 未指定）分离株中的 28 个，仅另一个非 O157 大肠杆菌血清型（O162:H7），以及测试的其他 13 种细菌均不受其影响。噬菌体未包含 PCR 评估的 stx1、stx2、eae 或 ehxA 毒力基因。在 5°C 时，在含有 >10⁷ PFU/ml 噬菌体 FAHEc1 的肉汤中，大肠杆菌 O157:H7 的对数减少了约 4 个单位。在 37°C 下孵育的薄切片牛肉上，用 3.2 × 10⁷ PFU/4 cm²肉片中可减少>2.7 个对数。在较低的噬菌体浓度（10³-10⁴ PFU/4 cm²片）下，噬菌体在 37°C 下在牛肉上复制。当噬菌体在模拟热剔骨和常规胴体冷却的条件下应用于牛肉片时，在最佳条件下应用噬菌体 FAHEc1 时，可测量到大肠杆菌 O157:H7 的减少约为 2 个对数。
