Microbiology Department, Campden & Chorleywood Food Research Association, Chipping Campden, Gloucestershire, UK.
J Appl Microbiol. 2008 Nov;105(5):1259-65. doi: 10.1111/j.1365-2672.2008.03859.x. Epub 2008 Aug 18.
This study compared the growth of different strains of Verocytotoxin-producing Escherichia coli (VTEC) in a range of selective enrichment media.
Turbidometric and impedance methods were used to determine the growth of VTEC in pure culture in different enrichment media. Ten strains failed to grow in buffered peptone water + vancomycin, cefsulodin, cefixime at 42 degrees C and some failed to grow, or grew poorly in E. coli (EC) medium supplemented with 20 mg l(-1) novobiocin and modified EC supplemented with 20 mg l(-1) novobiocin at 37 degrees C and 42 degrees C. Individual VTEC strains were sensitive to the selective agents in some media. Statistical analysis of the conductance detection times of 10 strains showed no overall effect of temperature alone (P = 0.66) but there were significant (P < 0.001) effects as a result of the combination of medium and temperature and these two factors were influenced by strain.
Growth of VTEC during enrichment is dependent on different factors alone or in combination. These include medium type, presence of certain selective agents or antibiotics, incubation temperature and the initial population of VTEC. Sensitivity to these conditions can be strain related.
This study highlighted differences in the ability of some enrichment media to support the growth of VTEC, making them unsuitable for the isolation of VTEC, especially low numbers of non-O157 strains.
本研究比较了不同产志贺毒素大肠埃希氏菌（VTEC）菌株在一系列选择性增菌培养基中的生长情况。
采用浊度法和阻抗法测定 VTEC 在不同增菌培养基中的纯培养生长情况。10 株菌在缓冲蛋白胨水+万古霉素、头孢磺啶、头孢克肟 42°C 条件下不能生长，部分菌在含 20mg/L 新生霉素的 E. coli（EC）培养基和 37°C、42°C 条件下添加 20mg/L 新生霉素的改良 EC 培养基中生长不良或生长缓慢。个别 VTEC 菌株对某些培养基中的选择性试剂敏感。对 10 株菌的电导检测时间进行统计分析，结果表明，单独的温度对检测结果没有总体影响（P=0.66），但培养基和温度的组合有显著影响（P<0.001），且这两个因素受菌株的影响。
增菌过程中 VTEC 的生长取决于单独或组合的不同因素。这些因素包括培养基类型、是否存在某些选择性试剂或抗生素、孵育温度和 VTEC 的初始数量。对这些条件的敏感性可能与菌株有关。
本研究强调了一些增菌培养基在支持 VTEC 生长方面的能力存在差异，这使得它们不适合 VTEC 的分离，尤其是低数量的非 O157 菌株。
