Rowan N J, Deans K, Anderson J G, Gemmell C G, Hunter I S, Chaithong T
Department of Bioscience, University of Strathclyde, Glasgow, Scotland.
Appl Environ Microbiol. 2001 Sep;67(9):3873-81. doi: 10.1128/AEM.67.9.3873-3881.2001.
Forty-seven strains representing 14 different Bacillus species isolated from clinical and food samples were grown in reconstituted infant milk formulae (IMF) and subsequently assessed for adherence to, invasion of, and cytotoxicity toward HEp-2 and Caco-2 cells. Cell-free supernatant fluids from 38 strains (81%) were shown to be cytotoxic, 43 strains (91%) adhered to the test cell lines, and 23 strains (49%) demonstrated various levels of invasion. Of the 21 Bacillus cereus strains examined, 5 (24%) were invasive. A larger percentage of clinically derived Bacillus species (20%) than of similar species tested from the food environment were invasive. Increased invasion occurred after growth of selected Bacillus species in reconstituted IMF containing glucose. While PCR primer studies revealed that many different Bacillus species contained DNA sequences encoding the hemolysin BL (HBL) enterotoxin complex and B. cereus enterotoxin T, not all of these isolates expressed these diarrheagenic genes after growth in reconstituted IMF. Of the 47 Bacillus isolates examined, 3 isolates of B. cereus and 1 isolate of B. subtilis produced the HBL enterotoxin after 18 h of growth in brain heart infusion broth. However, eight isolates belonging to the species B. cereus, B. licheniformis, B. circulans, and B. megaterium were found to produce this enterotoxin after growth in reconstituted IMF when assessed with the B. cereus enterotoxin (diarrheal type) reversed passive latex agglutination (RPLA) kit. It is concluded that several Bacillus species occurring occasionally in clinical specimens and food samples are of potential medical significance due to the expression of putative virulence factors.
从临床和食品样本中分离出的代表14种不同芽孢杆菌属的47株菌株，在复原婴儿奶粉（IMF）中培养，随后评估其对HEp-2和Caco-2细胞的黏附、侵袭及细胞毒性。结果显示，38株菌株（81%）的无细胞上清液具有细胞毒性，43株菌株（91%）能黏附于测试细胞系，23株菌株（49%）表现出不同程度的侵袭能力。在所检测的21株蜡样芽孢杆菌菌株中，5株（24%）具有侵袭性。临床来源的芽孢杆菌属物种（20%）的侵袭性高于从食品环境中检测的类似物种。在含有葡萄糖的复原IMF中培养选定的芽孢杆菌属物种后，侵袭能力增强。虽然PCR引物研究表明，许多不同的芽孢杆菌属物种含有编码溶血素BL（HBL）肠毒素复合物和蜡样芽孢杆菌肠毒素T的DNA序列，但并非所有这些分离株在复原IMF中生长后都表达这些致泻基因。在所检测的47株芽孢杆菌分离株中，3株蜡样芽孢杆菌分离株和1株枯草芽孢杆菌分离株在脑心浸液肉汤中培养18小时后产生了HBL肠毒素。然而，当用蜡样芽孢杆菌肠毒素（腹泻型）反向被动乳胶凝集（RPLA）试剂盒评估时，发现8株属于蜡样芽孢杆菌、地衣芽孢杆菌、环状芽孢杆菌和巨大芽孢杆菌的分离株在复原IMF中生长后产生了这种肠毒素。结论是，临床标本和食品样本中偶尔出现的几种芽孢杆菌属物种由于假定毒力因子的表达而具有潜在的医学意义。
