Bacillus cereus Contamination of Seeds and Vegetable Sprouts Grown in a Home Sprouting Kit

Sprouting seeds (alfalfa, mung bean and wheat) were purchased at local health food stores and examined for Bacillus cereus by the official AOAC method. Of 98 units collected, 56 (57%) were positive for B. cereus at levels ranging from 3 to >500 per g. Population levels of B. cereus on sprouts grown from naturally contaminated seeds in a home sprouting kit ranged from a mean of log₁₀ 3.72 for alfalfa to 5.39 for wheat; the log₁₀ mean for mung bean sprouts was 4.52. Washing contaminated sprouts for 10 min with warm tap water as recommended by the manufacturer of the sprouting kits reduced the B. cereus count for mung bean sprouts by approximately one log unit but was less effective for wheat sprouts. B. cereus populations large enough to cause food poisoning (>10⁵/g) frequently remained on wheat sprouts even after three wash cycles, and significant numbers of viable B. cereus remained on wheat sprouts even after cooking for 20 min.