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16
FOOD POISONING

There was one mild family outbreak notified of four cases but no causative
organism was found.
In April an outbreak of food poisoning involving 41 persons occurred in a canteen
where the catering was carried out by contract.
Specimens were obtained from four persons who had been affected, two of the
canteen staff and also a sample of the suspected dish which was stewed steak.
Laboratory investigation revealed that Heat Resistant Cl. Welchii (Haemolytic
Serological Type 5) was present in the specimens from the persons affected and one of
the canteen staff (who had tasted meat), and also in the sample of stewed steak.
It was found that the meat, which was sliced frozen chuck steak, was delivered to the
kitchen at 9.30 a.m. on 8th April and on receipt was washed and cooked with flour,
salt, pepper, gravy powder and garlic, brought to the boil and simmered until 11.45
a.m. It was then cooled in the coolest part of the kitchen, but was not actually
cool until 3.15 p.m. It was then put in the refrigerator. The meat was taken out
of the refrigerator at 8 a.m. on 9th April and, after skimming, was warmed. The
gravy was noticed to smell sour and accordingly it was poured away. After washing
the meat, which tasted sweet, a new gravy of dripping, flour, salt, pepper and
Worcester sauce was added.
The stew was plated up at 11 a.m. and kept on hot plates until serving time at
noon. After "between 20 and 30" portions had been served, it was noticed that they
were "frothy" and the dish was withdrawn. Another item served on the same day was
mince and it is reported that a few people who ate the mince had diarrhoea when gravy
was added. This gravy was made separately but could have been ladled with the same
spoon as the stew.
The contributory factors were considered to be
(a) Attempt to cool, in bulk, 30 lbs. meat, which was probably still at
blood heat in the centre for some considerable time after it was put in
refrigerator.
(b) Failure to realise that the gravy could not have been unfit for use unless
the meat itself was unfit for use. and
(c) Long period of hot-plating allowing heat resistant Welchii to multiply.
A meeting was held with representatives of the catering firm and these points
were discussed and future procedure suggested which would obviate the danger.