Sato S, Miura T, Saitoh Y, Sato I, Ohtomo Y
School of Allied Medical Sciences, Hirosaki University.
Kansenshogaku Zasshi. 1999 Aug;73(8):722-7. doi: 10.11150/kansenshogakuzasshi1970.73.722.
Growth of 10 strains of VTEC O157, which were isolated from faecal specimens, was evaluated in conventionally recommended enrichment broth media Trypticase soy broth (TSB) and Davis's Minimal Medium (DMM) at different temperatures. Five strains of VTEC O157 used in the test proliferated well in TSB and reached to 10(9) CFU/ml at 36 degrees C in 24 hours incubation and to the same population densities at 25 degrees C in 48 hours. Whereas in DMM at 36 degrees C there was no proliferation in 6 hours, but grew to 10(6) CFU/ml in 24 hours and 10(8) CFU/ml in 48 hours. Three strains of VTEC O157 tested at 25 degrees C grew to 1.52 x 10(4) CFU/ml in 24 hours, 1.67 x 10(8) CFU/ml in 48 hours and 6.80 x 10(8) CFU/ml in 72 hours. No proliferation was observed at 4 degrees C in 72 hours in growth TSB and DMM. The growth in glucose free DMM was found in 7 out of 10 strains, and 4 out of these 7 strains grew profusely to 10(5) CFU/ml in 48 hours. One out of 3 strains showed no proliferation but survived 72 hours postinoculation, decreasing from 179 CFU to 29 CFU in 100 microliters of medium. The other 2 strains became completely extinct in 48 hours after inoculation with 263 CFU and 2,420 CFU in 100 microliters of medium respectively. However, these 3 strains which showed no growth in glucose free DMM could proliferate in DMM containing 1/10 of the usual glucose concentration, at a rate depending on the concentration. In conclusion, it is suggested that the finding of increase of VTEC O157 in glucose free DMM would be a useful solution for the food poisoning problem caused by VTEC O157.
对从粪便标本中分离出的10株产志贺毒素大肠杆菌O157菌株，在常规推荐的富集肉汤培养基胰蛋白胨大豆肉汤（TSB）和戴维斯基本培养基（DMM）中于不同温度下的生长情况进行了评估。测试中使用的5株产志贺毒素大肠杆菌O157菌株在TSB中增殖良好，在36℃培养24小时后达到10⁹CFU/ml，在25℃培养48小时后达到相同的菌密度。而在36℃的DMM中，6小时内没有增殖，但在24小时内生长至10⁶CFU/ml，在48小时内生长至10⁸CFU/ml。在25℃测试的3株产志贺毒素大肠杆菌O157菌株在24小时内生长至1.52×10⁴CFU/ml，在48小时内生长至1.67×10⁸CFU/ml，在72小时内生长至6.80×10⁸CFU/ml。在生长的TSB和DMM中，4℃培养72小时未观察到增殖。10株菌株中有7株在无葡萄糖的DMM中生长，这7株中有4株在48小时内大量生长至10⁵CFU/ml。3株菌株中有1株未增殖，但接种后存活72小时，100微升培养基中的菌数从179 CFU降至29 CFU。另外2株菌株分别接种100微升培养基中263 CFU和2420 CFU后，在48小时后完全灭绝。然而，这3株在无葡萄糖的DMM中不生长的菌株能在含有通常葡萄糖浓度1/10的DMM中增殖，增殖速率取决于浓度。总之，有人认为在无葡萄糖的DMM中产志贺毒素大肠杆菌O157数量增加这一发现，对于解决由产志贺毒素大肠杆菌O157引起的食物中毒问题将是一个有用的办法。
