Purification and characterization of Enterobacter sakazakii enterotoxin

Enterobacter sakazakii has recently been recognized as an often fatal neonatal pathogen that rarely infects adults. Although not much is known about factors involved in its pathogenicity, the organism has been reported to produce enterotoxin. Currently, no information is available in the literature about the production and characterization of the enterotoxin. This report is the first attempt regarding purification and biochemical characterization of the enterotoxin produced from E. sakazakii. The toxin was purified by ammonium sulfate precipitation, followed by DEAE cellulose ion exchange and desalting by Sephadex G-100. The 66 kDa toxin was most active at pH 6 and was stable at 90 degrees C for 30 min. This stability combined with the potent activity of the toxin (LD50 = 56 pg) emphasizes the potential risk to neonates fed infant milk formula contaminated with E. sakazakii. Further detailed molecular biological studies on the toxin are warranted in view of its stability and activity.