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The organism concerned was identified as Salmonella typhimurium, phage type 29, a strain
known to spread easily, being resistant to various antibiotics and which was prevalent in the
London area at the time. This phage type is usually of bovine origin, infecting calves early in life,
and introduction into the hospital environment was presumably through the medium of calf meat
or of a human case or carrier.
Bacteriological screening of families of patients living in Westminster revealed three symptomless
excretors, none of whom was a food handler. Where the patients affected were not Westminster
residents, the respective Medical Officers of Health were informed in order that similar bacteriological
screening of close relatives could be arranged.
This outbreak highlighted very clearly the need to screen not only the patients, but also the
medical, nursing and domestic staff, before the "all clear" can be given from a bacteriological
standpoint. It also emphasised the importance of the closest liaison between the hospital and local
health authorities in containing the outbreak, including the follow-up of the families of those
affected. All local general practitioners, the Public Health Laboratory Service and the Ministry of
Health were kept fully informed of the position.
Some 80 persons were at risk where 22 members of the staff of another local hospital
were taken ill. The investigation was conducted by the hospital authorities themselves and
food remnants bacteriologically examined did not reveal the presence of any causative organism.
It is understood six members of the staff were admitted to the hospital wards.
At a Hospital Medical School in Westminster some 25 persons were affected with
diarrhoea and stomach cramp. Stool specimens and a sample of the veal consumed were both
positive for heat resistant Clostridium welchii. One feature of this outbreak was that the meals of
those affected were prepared in different kitchens, but the meat used was supplied by the same
butcher and was the only common dish eaten.
Diarrhoea and abdominal pain were suffered by 18 members of the staff of a large store
after a meal of roast beef at a canteen. Faecal specimens from seven of those affected were positive
for heat resistant Clostridium welchii, but ten specimens of food stuffs from subsequent servings
were all negative. The meat was cooked in large joints and possibly the heat penetration of a large
joint during the cooking process was insufficient to prevent the growth of organisms and the
production of toxin. The attention of the company concerned was drawn to certain matters which
required remedial action, and also to the importance of temperature control in the cooking of meat
dishes.
Two diners taken ill after a meal at a restaurant suggested that the steak and kidney pie was the
cause. Stool specimens showed the presence of Clostridium welchii. Investigation showed that
temperature control of meat dishes cooked on the premises was not in accordance with the Food
Hygiene (General) Regulations. 1960 which were explained to the proprietor.
Braised oxtail which had been cooked and left in the kitchen all night, and then reheated the
following morning for lunch at a restaurant, was the cause of illness of two patrons. Heat resistant
Clostridium welchii organisms were isolated from both food remnants and one of the patients;
the proprietor was warned accordingly.
Following a reception, some 70 persons were taken ill with diarrhoea and abdominal pain.
Clostridium welchii organisms were isolated from stool specimens, but as the information was not
received in this Department until some five days after the occurrence, none of the food from the
suspected meal remained. However, it was discovered that only those who had had the curried
chicken were affected, and that this dish and the mutton had been boiled at 11 p.m. on the evening
prior to consumption and left on the kitchen table in containers until reheated the following day
at noon. The proprietor of the restaurant was warned of the dangers associated with meat dishes
left at ordinary kitchen temperatures.
As will be noted from the foregoing, Clostridium welchii accounted for the majority of the
outbreaks of food poisoning which occurred in the City in 1967. It may be of interest to mention
that Clostridium welchii is a toxin producing spore bearing organisms which live in the intestine
of animals and man. It is sometimes found in meat as a result of contamination occurring either
before (the spores of the organism are heat resistant) or after cooking, and its presence produces
no detectable change in the meat. The danger arises when this meat is allowed to cool slowly or
is kept in a warm kitchen or preparation room for any length of time, or is warmed up later, or is
subjected to a combination of these conditions. The spores will then germinate and the resulting
organisms grow rapidly and produce a corresponding amount of toxins. It follows that meat
should either be cooked and immediately eaten hot or cooled rapidly and refrigerated within one
and a half hours until required.
Other cases of suspected food poisoning, involving one or two persons only in each case, were
investigated and appropriate action taken.