Introduction to Human Nutrition

330 Introduction to Human Nutrition

Table 14.2

Characteristics of food-borne bacterial infections

Bacteria

Comment

Food-borne illness

(a) Min. temp (b) Opt. temp (c) Min. pH

a

(d) Min. A

bw

Heat resistance

(a) Gram stain(b) Aerobic/

anaerobic

(a) Source(b) Associated foods

b

(a) Onset(b) Duration

(a) Symptoms(b) Infectious dose

Bacillus cereus

(diarrheal)

Vegetative cells are inactivated

by normal cooking temperatures; however, spores are quite heat resistant. The diarrheal enterotoxin is produced when spores germinate in the small intestine after consumption of contaminated food

(a) 8–16 h(b) 12–14 h

(a) Abdominal pain and

diarrhea

(b)

>^10

5 cells

(a) 10°C(b) 30–35°C(c) 4.3(d) 0.95

Heat-sensitive, but

forms heat-resistant spores (D

121

=

0.03–2.35 min)

(a) Gram positive(b) Facultative

anaerobe

(a) Soil and dust(b) Meat, milk,

vegetables, fi sh and soups

Clostridium

perfringens

Illness results from

consumption of food containing high numbers of cells (

>^10

6 /g) followed by

enterotoxin production in the large intestine. When contaminated food is cooked, sporulation is induced. As the food cools, the spores germinate and vegetative cells continue to multiply, unless the food is cooled quickly and stored under refrigerated conditions

(a) 12–18 h

(can be 8–22 h)

(b) 24 h

(a) Diarrhea and severe

abdominal pain

(b)

>^10

6 cells/g

(a) 15°C(b) 43–45°C(c) 5.0(d) 0.95

Heat-sensitive, but

forms heat-resistant spores (D

= 1.3–2.8 min) 95

(a) Gram positive(b) Obligate

anaerobe

(a) Soil and animal

feces

(b) Meat, poultry,

gravy, dried and precooked foods