Changes in enterococcal population during storage of reconstituted infant food

A six-fold increase in the enterococcal population was observed in reconstituted infant food samples after storage for 2 h at 37 degrees C. The increase in enterococcal counts at 40 degrees C and 45 degrees C was approximately five-fold during the same period. However, the corresponding total viable counts increased by twelve fold at these temperatures after 2 h. After 12 h, the enterococcal and total viable counts increased to 39 x 10(4) and 36 X 10(7) colony forming units per ml, at 37 degrees C respectively. A similar pattern in enterococcal and total bacterial count was observed at 40 degrees and 45 degrees C. TNase was detected in reconstituted infant food samples held at 37 degrees, 40 degrees and 45 degrees C, after 12 h, while pH values declined to 5.0, 5.1 and 5.2, respectively at the above temperatures. From TNase positive samples, an isolate S. faecium IF-100 capable to produce TNase was recovered. Storage of reconstituted infant food samples in the refrigerator (5 degrees C) resulted in a gradual increase in enterococcal population which reached 39 X 10(3) c.f.u. per ml after 12 days. However, TNase was not detected in any of these samples.