Serafim M B, Monteiro A R, de Castro A F
J Clin Microbiol. 1983 May;17(5):799-803. doi: 10.1128/jcm.17.5.799-803.1983.
With regard to the assay of heat-stable enterotoxin (ST) from Yersinia enterocolitica, we made a comparative study of the conventional infant mouse test read at 4 h and a modified infant mouse test read at 2 h. The influence of several factors, such as the medium used to prepare ST, lysing of bacterial cells from the broth cultures used to prepare ST, and the temperature at which the inoculated mice were kept during the test, was also investigated. Thus, with a few exceptions, Pai-Mors medium was more suitable than Casamino Acids-yeast extract medium, for the preparation of yersinial ST. Gut/carcass weight ratios obtained with lysed supernatants or with supernatants from whole cultures of Y. enterocolitica were similar, suggesting that most of the ST produced by this microorganism in broth cultures is extracellular. The amount of ST produced by Y. enterocolitica, as well as the ambient temperature at which inoculated mice were kept during the assay, was found to influence gut/carcass weight ratios obtained with both tests. Enterotoxigenicity and the temperature at which mice were kept were interrelated, such that for weakly enterotoxigenic strains there were no significant differences among gut/carcass weight ratios for the conventional and modified infant mouse tests carried out at 18 or 25 degrees C, but at 30 degrees C the values in the modified test were higher for most ST preparations with Pai-Mors medium. The influence of ambient temperature was more pronounced at 37 degrees C, since most strains produced negative results in the conventional test at this temperature. We conclude that the conventional infant mouse test is adequate for assaying yersinial ST, provided that the temperature at which mice are kept during the assay is fixed at around 25 degrees C.
关于小肠结肠炎耶尔森菌热稳定肠毒素（ST）的检测，我们对4小时读数的传统幼鼠试验和2小时读数的改良幼鼠试验进行了比较研究。还研究了几个因素的影响，例如用于制备ST的培养基、用于制备ST的肉汤培养物中细菌细胞的裂解以及试验期间接种小鼠所处的温度。因此，除了少数例外情况，Pai-Mors培养基比酪蛋白氨基酸-酵母提取物培养基更适合用于制备耶尔森菌ST。用裂解上清液或小肠结肠炎耶尔森菌全培养物的上清液获得的肠/胴体重量比相似，这表明该微生物在肉汤培养物中产生的大多数ST是细胞外的。发现小肠结肠炎耶尔森菌产生的ST量以及试验期间接种小鼠所处的环境温度会影响两种试验获得的肠/胴体重量比。产肠毒素性和小鼠所处温度相互关联，以至于对于弱产肠毒素菌株，在18或25℃进行的传统和改良幼鼠试验的肠/胴体重量比之间没有显著差异，但在30℃时，对于大多数用Pai-Mors培养基制备的ST制剂，改良试验中的值更高。在37℃时环境温度的影响更为明显，因为大多数菌株在此温度下的传统试验中产生阴性结果。我们得出结论，只要在试验期间小鼠所处的温度固定在25℃左右，传统幼鼠试验就足以检测耶尔森菌ST。
