Growth and enterotoxin production by diarrhoeagenic Bacillus cereus in dietary supplements prepared for hospitalized HIV patients.

This study was initiated because of an increase in diarrhoeal episodes in a ward caring for patients infected with the human immunodeficiency virus (HIV). An examination of hospital-prepared dietary supplements (build-up food) found Bacillus cereus to be a potential problem. Due in part to inadequate refrigeration conditions (13 +/- 4 degrees C), the microbial flora in commercially pasteurized semi-skimmed milk (PSSM) reached potentially hazardous levels (> 10(6) cfu/mL). While refrigerated PSSM did not support enterotoxin production, reconstitution of build-up powder in PSSM followed by storage in the HIV ward (4 h at 28 +/- 3 degrees C) resulted in growth of B. cereus (> 10(7) cfu/mL) and synthesis of diarrhoeal enterotoxin. While insufficient epidemiological data was available to establish conclusively a causal relationship between patients' symptoms and source, the study highlights a potential B. cereus problem with hospital-prepared dietary supplements and recommendations are proposed to prevent this re-occurrence.