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In none of the specimens of faeces examined from the five persons who had not returned to
work on 20th April were Clostridium welchii or other intestinal pathogens obtained.
From the clinical symptoms and the bacteriological report on the roast beef, this appears to
be a typical outbreak of mild food-poisoning due to a heat-resistant strain of Clostridium welchii,
and I have little doubt that if the beef had been cooked and eaten the same day, instead of
being cooked the day before, stored overnight and warmed up and served the next day, the
outbreak would not have occurred. These large pieces of meat take a long time to cool, and
therefore there is a considerable period during which the temperature is favourable for the growth
and multiplication of any sporing organisms, such as Clostridium welchii, which survive the
cooking. There is probably further multiplication next morning when the meat is cut up and
kept warm till it is served.
The kitchen of this canteen was inspected and found to be satisfactory. No illness had
occurred amongst the canteen staff previous to the outbreak, though one member was ill after
eating the beef. A sample of feces in her case was reported free from Clostridium welchii or
other pathogenic organisms.
Incident No. 3.
On 27th April, I was informed that eight persons had developed symptoms of food-poisoning,
vomiting and diarrhoea, some three to five hours after eating lunch at a staff canteen. Altogether
1,300 lunches had been served on that day.
The menu comprised grilled fillet of sole, fish cakes, roast lamb, liver and bacon, braised
lamb, beef and ham pasty, cheese and tomato on toast, hors dœuvres, sultana roll and custard,
semolina pudding, trifle with mock cream, jelly, ice-cream, biscuits and cheese.
No single item of diet was common to all sufferers, nevertheless specimens of roast lamb,
jelly crystals, mock cream and custard powder, being available, were sent for bacteriological
examination. Specimens of feces were obtained from 6 cases and bacteriologically examined.
The clinical symptoms and the period between the meal and the onset of illness were
suggestive of poisoning by the toxins of staphylococci, and it was thought that the mock cream
might be the vehicle of infection, but no organisms associated with food-poisoning were recovered
from the samples of food or of feces submitted.
The cause of this very limited outbreak, only 8 persons out of 1,300 at risk, remains a mystery.
Incident No. 4.
On 12th August a report was received that about 20 people had been taken ill after a luncheon
meal in a commercial canteen in the City.
The symptoms were abdominal pain and diarrhoea, but no vomiting, coming on from 7 to 14
hours (average 10½ hours) after the meal and persisting for 8 to 24 hours.
The menu included grilled halibut, chicken and ham vol-au-vent and gravy, braised ox tail
and gravy, bacon, tomato and mushroom pancakes, egg salad, beans, onions, potatoes, rhubarb
charlotte, peach condé, milk-pudding, mousse, ice-cream, custard, jelly, biscuits and cheese.
The only food available for bacteriological examination were some vol-au-vent and fish. The
report on these was negative.
About 1,200 lunches were served on the day in question and it is remarkable that only 18
persons were affected. Ten of these were engaged in the preparation or service of food, and it
was decided to have bacteriological examination of samples of feces from as many of the canteen
staff as would consent. The Company concerned has a medical department who were most cooperative,
and 53 fecal specimens were submitted for bacteriological examination.
Heat-resistant Clostridium welchii were isolated from 5 specimens. In three cases the donors
had not been ill and in two they had.
Further examination of these organisms at the Central Public Health Laboratory revealed
that in the two cases who had had symptoms the organisms were food-poisoning strains of
Clostridium welchii, in the other three they were not.
It appears, therefore, that this was another mild outbreak of food-poisoning due to heatresistant
Clostridium welchii. What the vehicle of infection was is uncertain, but may have
been the gravy served with both the vol-au-vent and the braised ox tail.
It is not possible to suggest any reason why only 18 out of 1,200 persons should have been
affected. I thought perhaps that those who were taken ill might have been those who took the
meal late when there had been time for incubation of any organisms introduced during preparation
of the food, but I found that times varied from 11.30 a.m. to 2.15 p.m.
The canteen is well equipped and maintained, except that the refrigerated storage space is
barely adequate. This is being remedied; also a continuous roller towel by the lavatory basin in
the kitchen is being replaced by paper towels.
Incident No. 5.
On 8th September, a telephone message was received from a City firm that a number of
members of their staff had been indisposed and that they suspected the water supply. Some
internal work had been carried out on the service main to the canteen on the previous day, 7th
September. The Metropolitan Water Board were notified and took samples of the water which
on bacteriological chemical examination proved to be of the usual high standard of the Metropolitan
Water Board supply.