KensingtonIt has been shown that heat-resistant Cl. welchii may be the cause of food-poisoning (Oesterling, 1952; Hobbs et al., 1953). The clinical picture of this condition is described by these authors as that of a pure lower-bowel affection-that is, diarrhoea and gripingwithout the vomiting and general symptoms, such as pyrexia and headaches, seen in food-poisoning due to staphylococci and salmonellae. The usual medium of infection is a meat dish which has been prepared the day before being consumed and has been kept under conditions favourable to the multiplication of bacteria. The relatively mild and short course of this illness and the fact that it is caused by an anaerobe which will escape detection in the usual tests for intestinal pathogens probably explain why this type of foodpoisoning has attracted little attention before. Description of OutbreakWe recently had an opportunity of investigating such an outbreak in a general hospital in which 44 persons were affected-39 patients and 5 staff. The number of persons at risk was approximately 360. The cases were distributed among seven wards of the 450-bed hospital. The persons affected fell ill about 8-16 hours after consumption of some roast pork served for lunch. The pork had been cooked the day before and was allowed to cool for about three to four hours in the open before being stored in the refrigerator. The next morning it was sliced in the kitchen, and freshly prepared hot gravy was added before it was distributed in closed hot trolleys to the wards.The same night a number of patients fell ill with diarrhoea and acute abdominal pain; the stools were watery and only occasionally some mucus was present; one person had blood in the stool. There was no vomiting, but some patients complained of slight nausea; no pyrexia was noted. Most of the patients recovered by the following midday or evening. Bacteriological InvestigationsStool samples of all persons affected and of the kitchen staff were cultured. In addition a remnant of the suspected roast pork and 12 random samples of raw pork from the kitchen refrigerator were examined; the latter were taken from joints which were derived from five different sides; the side from which the remnant of roast pork came could not be identified. None of the gravy was left. The faeces, in addition to being subjected to the routine examination for intestinal pathogens, were inoculated into bottles of meat broth; these were steamed for one hour, incubated overnight, and then subcultured on to anaerobic blood-agar plates. In positive cases an almost pure growth of Cl. welchii was obtained. The colonies had the characteristic appearance of this organism except for the initial absence of haemolysis, which, however, developed after a few days' standing. They gave a positive Nagler reaction which was suppressed by Cl. welchii type A antitoxin. JE TO CL. WELCHII BRmIS MEDICAL JOURNALSmears prepared from the remnant of roast pork and the samples of raw pork revealed numerous Gram-negative and Gram-positive bacilli, some of the...

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