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served first escaped unscathed, while those children and members of the staff who were served later
with custard which had stood in contact with the sides and bottom of the container were affected.
No samples of the suspected food were available for examination.
The outbreak in a commercial canteen appears definitely to have been due to heat resistant
Clostridium welchii, and this organism was recovered from two samples of faeces submitted to the
Food Hygiene Laboratory at Colindale.
The food responsible was imported pigs hearts. These were received in a hard frozen condition
on a Friday and were put in a refrigerator in the canteen. After lunch on the following Monday, the
chef cleaned the pigs' hearts and put them into cold water in two large boilers. They were then
boiled for about an hour and a half, but the chef admitted that it would take at least three-quarters
of an hour for the large quantity of cold water plus the frozen hearts to come to the boil. The hearts
were therefore actually boiled for half-an-hour or less. They were then taken off the cooking range
and left to stand in the warm water in the kitchen till about 10 o'clock next morning, some 17 or 18
hours. They were then heated again for one hour, which means that they were at boiling point for
less than half-an-hour.
The conditions for survival and multiplication of a heat resistant strain of Clostridium welchii
were therefore ideal ; some 17 hours in warm water from which the air had been driven out during
the short period of boiling.
The pigs hearts in question were only a small part of a consignment of 1,000 lbs. distributed by
an Acton butcher, and at my request the Medical Officer of Health of Acton kindly enquired as to the
distribution of the remainder; whether they had given rise to any cases of food-poisoning, and
whether they had been cooked and eaten the same day. It was ascertained that the remainder of the
consignment had been distributed to a hospital and six staff canteens in the Acton area. The hearts
had been cooked and eaten on the same day in six instances, and in the seventh instance, though they
had been eaten the day after cooking they had been kept overnight in a refrigerator.
Though I reported in detail on this occurrence at the time to the Public Health Committee and
to the Ministry of Health, I have thought it worth while including a full summary in my annual
report because it is a classical example of an outbreak of food-poisoning due to heat resistant Clostridium
welchii, and demonstrates clearly the danger of insufficient cooking, followed by a number of
hours of storage at room temperature or higher and then merely warming up just before serving. Pigs
hearts from the same consignment were dealt with in eight different kitchens. In six they were cooked
and eaten on the same day and no food-poisoning occurred. In one instance they were cooked one
day and eaten the next but were placed in a refrigerator overnight, again no food-poisoning occurred.
In the eighth case they were cooked one day, stored in the water in which they had been boiled in a
warm kitchen overnight, raised to the boil next day and served, and about 60 cases of food-poisoning
resulted. The symptoms were abdominal pain and diarrhoea coming on from 6 to 18 hours after the
meal. There was no vomiting. Most of the patients were at work the next day, though some still
complained of looseness of the bowels. I believe that all had recovered in 48 hours, except one who
had a relapse and was ill for a week.
The cooking of meat in the afternoon of one day for consumption at luncheon the next day is
quite a common practice in canteens, because there often is not time to prepare large quantities of
food between the time of arrival of the kitchen staff in the morning and noon, when the service of lunch
commences. This practice is not dangerous if the food is rapidly cooled after cooking and kept cool
overnight. The danger is greater in restaurants and canteens than in domestic kitchens because the
bulk of the food is greater, consequently the penetration of heat in cooking is slower and subsequent
cooling is also slower. There is therefore more chance of organisms surviving and more time at a
suitable temperature for survivors to multiply than is the case with the smaller quantities dealt with
in ordinary home-cooking.
It is, however, quite probable that many cases of mild food-poisoning of this type occur in the
home but are never heard of. Recovery is usually rapid and complete, no doctor is called in, and the
patients are content to say that they must have eaten something which upset them and leave it at that.
They try to recollect whether anything they have eaten tasted "a bit off," not realising that foodpoisoning
is not due to the decomposition of food, but to specific organisms which do not usually
affect the smell or the taste of the food.
The human body can probably deal even with these specific organisms in relatively small numbers,
but at anything approaching the temperature of the body, they multiply very rapidly and in a few
hours may be present in such numbers as to overcome the consumer's powers of resistance. It is
difficult, if not impossible, to protect all food during distribution and preparation from contamination
with one or other of the organisms capable of producing the symptoms of food poisoning, but it is
numbers that count, and for that reason not only is it necessary to reduce contamination to a minimum
by strict attention to cleanliness at every stage of the distribution and preparation of food, but food
must be kept cool to prevent multiplication of organisms ; should be well cooked to kill as many
organisms as practicable without spoiling the food, and should then be eaten promptly. If it is not
possible or desirable to eat it at once, or if any is left for consumption at a later date, it must be
cooled rapidly and kept cool, in order to prevent the multiplication of any organisms which have
escaped destruction during cooking or which have gained access to the food during handling subsequent
to cooking.
If these simple facts were appreciated by all who are responsible for the handling and preparation
of food, there would be few outbreaks and indeed few individual cases of bacterial food poisoning.
I am indebted to the Medical Officer of Health of Acton for investigating the distribution and
method of preparation of the remainder of the large consignment of pigs hearts, and to the Medical
Officer of Health of Watford for obtaining and sending to the Central Public Health Laboratory
samples of faeces from patients ill at home in his district.
Hygiene of Catering Establishments.
Two of your Sanitary Inspectors, Mr. Thompson and Mr. Flynn, devote their whole time to the
inspection of catering establishments, and over a number of years have accumulated a wide and
varied experience in the City of London, and one of them, Mr. Flynn, in the City of Westminster also.
They have jointly submitted the following report:—
"During the twelve months under review there have been no startling departures from the
normal routine work of the department. However, the opportunity has arisen to go back over some