The Medical Research Council has issued a special report by Dr. W. G. Savage and Mr. Bruce White on food poisoning, based upon a study of 100 recent outbreaks in this country, most of which have not been previously published. The Report is prefaced by a general survey of the different causes of outbreaks of food poisoning, the epidemiological and clinical features of food poisoning, the paths of infection, and prevention of food poisoning. The report is a continuation of the special investigations of Dr. Savage and Mr. White, published in the Medical Research Council Report No. 91, and entitled “An investigation of the salmonella group, with special reference to food poisoning,” which dealt chiefly with the classification and distribution of the salmonella bacteria. By far the commonest cause of food poisoning in this country is infection of food by living salmonella bacteria or by the toxins of these microbes. Salmonella bacteria multiply rapidly in food without betraying their presence by any obvious decomposition, and they secrete powerful endotoxins capable of resisting temperatures as high as 100° C. In 20 of the 100 outbreaks recorded in this report living salmonella bacteria were proved to be the agents of infection, and in 14 of these 20 outbreaks B. aertrycke was the particular member of the group found. The isolation of these bacilli is a difficult procedure, for they are factidious in their diet, and it is worth while noting, in view of the remarks we make elsewhere about the more thorough investigation of outbreaks of food poisoning, that in 6 of these outbreaks the bacilli were only captured from material obtained at post‐mortem examinations; if this material had not been available the bacterial cause would not have been definitely established, though deductions might, of course, have been made from other examinations. It is well known that food in which salmonella bacteria have grown may continue to be poisonous after the bacilli themselves have been destroyed, because the toxin which these germs secrete is more resistant to heat than are the living cells. Food poisoning by the toxins of the salmonella bacteria alone is perhaps the most difficult of all to analyse, because ingestion of these toxins leaves no specific stamp upon the body tissues: thus agglutinins do not appear in the blood serum. It might be thought that the poisonous nature of the food could be demonstrated by feeding experiments on animals, but this method is not often successful because animals are exceptionally resistant to these toxins. The method of injecting extracts of suspected food parenterally has led to many false conclusions in the past, and does not now command much confidence. A promising new method of study was referred to in Report 91—namely, the possibility of demonstrating toxic properties in food by feeding animals with large quantities, killing the animal nine to twelve hours afterwards, and examining the stomach and intestines for evidence of inflammatory reaction. Another new method which we believe Dr. Savage was the first to employ, at any rate on an extensive scale, is the demonstration of the production of specific agglutinins to the salmonella bacilli through the injection into animals of suitable emulsions of the incriminated food. By one method of investigation or another the authors of this report have satisfied themselves that 17 out of the 100 outbreaks should be ascribed to salmonella toxins. Four of the outbreaks were caused by bacteria of the dysentery group. The chief interest of this observation is that it widens our view of food poisoning, for until recently it would have been denied that bacteria of the dysentery type could cause outbreaks of food poisoning indistinguishable in their clinical characters from salmonella infections. Only one outbreak of botulism—that at Loch Maree—is presented in this series. To summarise the cause of these 100 outbreaks of food poisoning, epidemiological and laboratory investigations, separately or together, provided evidence that 66 outbreaks were due to members of the salmonella group of bacilli, 4 to members of the dysentery group, and 1 to B. botulinus. The remainder were either of definitely chemical origin, or possibly due to some undetected microbe, or were not examples of true food poisoning.
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