Suo Biao, Wang Yuexia
College of Food Science and Technology, Henan Agricultural University, China.
College of Life Sciences, Henan Agricultural University, China.
Braz J Microbiol. 2014 Jan 15;44(3):737-42. doi: 10.1590/s1517-83822013000300011. eCollection 2013.
Although many rapid and high throughput molecular methods have been developed in the recent years for the multiplex detection of foodborne pathogens, the simultaneous recovery and enrichment of sublethally injured cells is still a problem that needs to be considered. Combined with previous established multiplex real-time PCR assay, the capability of simultaneous recovery and enrichment of sublethally injured Salmonella, E. coli O157:H7 and L. monocytogenes cells was evaluated in a multiplex selective enrichment broth SEL. The injured cells were obtained by heat shock. After evaluation of different procedures, 1 h of recovery period prior to 20 h of enrichment was proved to be necessary for the detection of less than 10 CFU/5 mL broth of injured L. monocytogenes. When the detection method was applied to artificially contaminated ground beef, all the three injured pathogens could be simultaneously detected without discrimination by real-time PCR combined with SEL broth, the detection limit was < 5 CFU/10 g ground beef. Comparatively, when BPW was employed as the enrichment broth in the same detection procedure, injured L. monocytogenes could not be detected if the initially spiked level was below 10(2) CFU/10 g ground beef. Considering the capability of co-enrichment and high detection effectiveness, the real-time PCR assay combined with SEL broth herein appears to be a promising tool for high-throughput screening of a large number of processed food samples, which require either single or multiple pathogen detection. More important, the sublethally injured foodborne pathogen cells were also detectable.
尽管近年来已开发出许多快速且高通量的分子方法用于食源性病原体的多重检测，但亚致死损伤细胞的同步回收和富集仍然是一个需要考虑的问题。结合先前建立的多重实时PCR检测方法，在多重选择性富集肉汤SEL中评估了亚致死损伤的沙门氏菌、大肠杆菌O157:H7和单核细胞增生李斯特氏菌细胞的同步回收和富集能力。通过热休克获得损伤细胞。在评估不同程序后，证明对于检测每5 mL肉汤中少于10 CFU的损伤单核细胞增生李斯特氏菌，在富集20 h之前需要1 h的恢复期。当该检测方法应用于人工污染的绞碎牛肉时，通过实时PCR结合SEL肉汤可以同时检测到所有三种损伤的病原体，而不会产生区分，检测限为<5 CFU/10 g绞碎牛肉。相比之下，当在相同检测程序中使用BPW作为富集肉汤时，如果最初接种水平低于10(2) CFU/10 g绞碎牛肉，则无法检测到损伤的单核细胞增生李斯特氏菌。考虑到共富集能力和高检测效率，本文所述的实时PCR检测方法结合SEL肉汤似乎是用于大量加工食品样品高通量筛选的有前途的工具，这些样品需要检测单一或多种病原体。更重要的是，亚致死损伤的食源性病原体细胞也可被检测到。
