Morris B J, Buse H Y, Adcock N J, Rice E W
Pegasus Technical Services Inc., Cincinnati, OH, USA.
National Homeland Security Research Center, US Environmental Protection Agency, Cincinnati, OH, USA.
Lett Appl Microbiol. 2017 Jun;64(6):394-400. doi: 10.1111/lam.12725. Epub 2017 May 3.
Francisella tularensis is a fastidious organism that requires a lengthy incubation time in liquid growth media for detection. The objective of this study was to develop a medium formulation using readily available supplements that enhanced early growth of F. tularensis. Francisella tularensis live vaccine strain was used to evaluate the growth responses for each of the media formulations tested. Growth in brain heart infusion broth supplemented with 2% Vitox, 10% Fildes and 1% histidine (BVFH) resulted in a significant increase in growth after 8 h incubation compared to other media formulations tested (P < 0·001). Virulent strains of F. tularensis grown in BVFH medium demonstrated similar enhanced early growth. Cell densities of 3·9-5·2 log CFU per ml were obtained after 24 h of growth in BVFH from a 1-2 cell ml starting inoculum of the virulent Type A Schu4 strain, indicating the suitability of this medium in rapidly amplifying low starting titres of F. tularensis. Collectively, these results indicate that the novel formulation of the BVFH medium was capable of producing enhanced growth response for F. tularensis.
The need for rapid cultivation of Francisella tularensis is essential for detection and monitoring during natural outbreak events or intentional bioterrorism attacks. The addition of selected supplements into the base medium BHI (BVFH) developed in this study enhanced growth of F. tularensis Type A1, A2 and B strains compared to BHI alone. Growth of these organisms in BVFH will allow for improved response time should a natural or intentional contamination event occur.
土拉弗朗西斯菌是一种苛求菌，在液体生长培养基中检测需要较长的孵育时间。本研究的目的是开发一种使用易于获得的补充剂的培养基配方，以促进土拉弗朗西斯菌的早期生长。使用土拉弗朗西斯菌活疫苗株评估所测试的每种培养基配方的生长反应。与其他测试的培养基配方相比，在补充有2% Vitox、10% 费氏消化物和1% 组氨酸的脑心浸液肉汤（BVFH）中孵育8小时后，生长显著增加（P < 0·001）。在BVFH培养基中生长的土拉弗朗西斯菌强毒株表现出类似的早期生长增强。从强毒A型舒4菌株的1-2个细胞/毫升起始接种物在BVFH中生长24小时后，获得的细胞密度为每毫升3·9-5·2 log CFU，表明该培养基适用于快速扩增低起始滴度的土拉弗朗西斯菌。总体而言，这些结果表明BVFH培养基的新配方能够对土拉弗朗西斯菌产生增强的生长反应。
在自然爆发事件或故意生物恐怖袭击期间进行检测和监测时，快速培养土拉弗朗西斯菌至关重要。与单独的脑心浸液（BHI）相比，在本研究中开发的基础培养基BHI（BVFH）中添加选定的补充剂可增强土拉弗朗西斯菌A1、A2和B型菌株的生长。如果发生自然或故意污染事件，这些生物体在BVFH中的生长将缩短反应时间。
