Introduction to Human Nutrition

Food Safety 329

Staphylococcus

aureus

Food handlers play a major

role in transmission. S. aureus is carried in nose/throat of ~40% of healthy individuals and can be easily transferred to food via the hands. Most implicated foods have been ready-to-eat foods that have been contaminated by poor handling practices and stored at incorrect temperatures, allowing S. aureus

to grow to levels

(>

10

5 cells/g) that will

produce suffi cient heat-stable staphylococcal toxin

(a) 1–6 h(b) 1–2

days

(a) Nausea,

vomiting, abdominal pain and diarrhea

(b)

<1.0

μg toxin

(>

10

5 cells/g

needed to produce suffi cient toxin)

(a) 7°C(b) 35–37°C(c) 4.5(d) 0.83

No

Toxin: heat

resistant (able to withstand boiling for up to 30 min)

(a) Gram

positive

(b) Facultative

anaerobe

(a) Exposed skin lesions,

nose, throat and hands

(b) Generally foods of

animal origin that have been physically handled and have not received a subsequent bactericidal treatment

a Under otherwise optimal conditions; limits will vary according to strain, temperature, type of acid (in the case of pH), solut

e (in the case of A

), and other factors.w

b Not an exhaustive list.Min., minimum; Opt., optimal; A

, water activity.w