Popular Science Monthly/Volume 35/June 1889/Mischief-Makers in Milk
By ALICE B. TWEEDY.
VERY recently it was announced by Proust that the bicarbonate of soda used as a preservative of milk formed a compound particularly injurious to children—i. e., the lactate of soda. There appears to be great danger, in the newly aroused fear of fermentative changes in food and of the baneful products of the busy bacilli, that any vaunted preservative or germicide may be greedily seized upon at once, without thought as to the innocence of its chemical activity. This easy credence in antiseptics seems to be characteristic of the minds that shrink with most unreasoning fear from every advance in bacteriological research. Not long since, a novelist, more imaginative than scientific, arraigned Science because "the idea of the comma bacillus is more dreadful than that of the cholera." This, as an outburst of ignorance, would be excusable, preferring the known horror to the immeasurable unknown. But, to one acquainted with the fact that infinitesimal life swarms about and within us, why should it be terrible to learn that some forms are coincident with disease? If we thrive upon palpitant air, drink water populated with bacteria, and shelter millions of microbes in our bodies, why should we tremble to find a few unfriendly species that we can not safely entertain? We talk glibly of "pure air" and "pure water"; but, to be exact, we have only a laboratory knowledge of either, and might as well try to rid ourselves of our surplus population as to provide ourselves with these elements in a sterilized state.
"Dead" and "undesirable" may be equivalent terms in regard to air and water, but we do not yet know whether they can be applied to food. All of the bacilli that visit our articles of diet seem to herald some fermentative or putrefactive change. Sometimes these are agreeable to us, and we aid them in their work of creating yeast, wine, and kumyss. Even then we watch closely and fix a limit to their activity. Generally, we are squeamish about their advent in meat, milk, cheese, or eggs, having dire experience of the alkaloids that they manufacture. And, it must be noted, it is not the bacilli themselves that give us trouble; for all we know they may be as digestible as the cholera bacillus was to M. Roche Fontaine. It is the physiological result of their sojourn in the food that constitutes the danger—the unfortunate remainder, or ptomaine, that may be fatal to us. This ptomaine is an alkaloid formed from the medium in which the organism exists, and includes whatever substance may be left of the bacterium itself. Just as man changes the atmosphere about him by exhaling carbonic-acid gas and various solid particles of matter, so the bacillus decomposes the tissues and fluids of the body in which it resides.
Nothing more wonderful than this work of disintegration is revealed to us in the economy of Nature. The picture of species after species accomplishing, by a brief life, one step toward the final resolution of organic matter into the elementary products, is not surpassed by a study of the glacial chiseling of the rocks, nor of the marvelous influence of the earth-worm in fructifying the soil.
Obviously, we can not wait for the manufacture of any poison, but must make it an impossibility, if we can, without rivaling any of the toxic effects by our remedies. Acquaintance is occasionally made with the ptomaine before the guilty micrococcus is known; in such cases even more care must be exercised.
Following the investigations of Lister and Hueppe, the ordinary fermentation of milk is traced to the growth of a microorganism known as Bacterium lactis, which converts the milk-sugar into lactic acid. The work of decomposition is then taken up by another bacillus, named subtilis, through which butyric acid is produced. Recent experiments made in the cultivation of milk bacteria by Baginski indicate that the Bacterium lactis is incorrectly named, and, being responsible for an acetic-acid formation, is better termed aceti.
There is also a peculiar fermentator, Bacterium coli, that refuses to meddle with milk-sugar alone, but upon the addition of white of egg shows extraordinary activity, furnishing lactic, formic, and acetic acid. These three—Bacterium aceti, Bacillus subtillis, and Bacterium coli—are the normal visitants of milk, and the changes dependent upon their presence are well understood. The microorganisms that breed disease and death appear under exceptional circumstances, against which, so far as they are known, we may carefully guard.
The bacilli of phthisis, typhoid, and scarlet fever have been detected in milk supposed to be wholesome. Thorough inspection of cattle and dairies may reduce the frequency of infection; but, until such supervision is the rule, all danger can be avoided by boiling the milk. In the late Congress at Paris on the study of tuberculosis. Dr. Nocard advised this to be done in every case where there existed any tendency to consumption.
A peculiar sickness, which in its malignant form is similar to anthrax, has been traced to a germ occurring in milk. The conditions required for its development are known, and have been artificially produced by feeding cattle with fodder exposed to the dew-fall. The poison is found in sweet milk, butter, cream, and cheese, but not in buttermilk. It is either formed in small quantity, or has the property attributed to it of self-attraction. Neither the ptomaine nor the bacillus producing it has been determined, and they offer a new field for experiment.
The chief mischief-maker is yet unknown, unless it may possibly be identical with the micrococcus found by Dr. Sternberg in cheese. Its ptomaine, however, was isolated by Prof. Vaughan, of the University of Michigan, in 1885, and was called, from the substance in which it was discovered, tyrotoxicon—cheese-poison.
The history of this discovery is interesting. Three hundred cases of cheese-poisoning were recorded in Michigan by the Board of Health during 1883 and 1884. Although none of these were fatal, the illness was in some instances alarming, and the evil effects were confined to twelve different cheeses. Samples of these were sent to Prof. Vaughan for analysis. The cheese exhibited no unusual taste or odor, but a dog, with keener instinct than the human, selected a piece of untainted cheese in preference. The detection of the poison proved to be a difficult task. The ptomaine was volatile and unstable, and a method had to be invented for its isolation. An alcoholic extract of the cheese fixed the poison in a fatty acid. An aqueous extract was made and evaporated, when the poison also disappeared. Two years of patient study perfected the process, and Prof. Vaughan succeeded in separating the ptomaine in crystalline shape. During the same year he obtained tyrotoxicon from milk kept in stoppered bottles in the laboratory.
In 1886 there occurred some cases of mysterious poisoning at Long Branch. Twenty-four persons became suddenly ill at one hotel, nineteen at another, and in the following week thirty more complained of similar symptoms. The investigations conducted by the chemists, Newton and Wallace, established the fact that tyrotoxicon was the cause of the sickness. The conditions in which the poison was generated are given in the report as follows: "The noon's milking—which alone was followed by illness—was placed while hot in the cans, and then, without any attempt at cooling, carted eight miles during the warmest part of the day in a very hot month"! Milk-poisoning in Iowa and Michigan was subsequently traced to the formation of tyrotoxicon; and, in India, an English surgeon. Firth, discovered the same ptomaine in milk that occasioned sickness.
It might be supposed that so favorable a nidus as custard would not be overlooked by the mischievous bacillus. After Vaughan's method of isolating the ptomaine was made known, many analyses of poisonous ice-cream and cream-puffs testified to its industry. Wherever this toxic agent was identified, the circumstances attending its growth were carefully studied, and the care of the milk, cream, or custard was found to be faulty. In some instances cleanliness had been strictly observed, but other conditions inducing fermentation had been overlooked. In the milk-poisoning at Long Branch proper airing and cooling of the milk were neglected. In Milan, Mich., three fatal cases occurred in the tidy home of a farmer's family. Examination showed that the buttery where the milk was kept had a new floor laid over decaying boards, and some of the dirt accumulations between these, taken to the laboratory, generated tyrotoxicon in fresh milk. In Lawton, Mich., the custards prepared for freezing stood for some hours in an unventilated building formerly used as a meat-market. The ice-cream made from them poisoned eighteen persons.
According to Prof, Vaughan, tyrotoxicon does not develop below 60° Fahr., and is anaërobic—grows when air is excluded. Some very simple measures, then, are preventive:
1. Scrupulous cleanliness. A little dry milk on the rim of a can or vessel may breed the germ which will find a culture-ground in fresh milk.
It is but just to say that these precautions are generally observed by careful dairymen and cream manufacturers. There is grave reason to fear, however, that they are not generally observed after the milk reaches the consumer's hands. Also, the slightest carelessness may affect seriously that class of the community which does not speak for itself—the very youngest.
The symptoms of cholera infantum and poisoning by tyrotoxicon have been proved experimentally to be very much alike, if not identical. Even the post-mortem condition of children dying with this complaint is shown by Prof. Vaughan to agree exactly with that caused by tyrotoxicon-poisoning in animals. The enormous per cent of deaths from the disease occurs between the ages of six months and two years, proving conclusively that heat and atmospheric conditions can not be the potent causes. There is only one differing factor in the life of those under six months and older children—the food. The younger class, then, must escape, because a greater majority of them are naturally nourished. Statistics prove with increasing testimony that all artificial feeding is not only unnatural but hazardous, and to be successful requires the most intelligent attention. However, if all mothers and nurses could learn that milk exposed to foul or warm air for any length of time may not only sour, but become the vehicle of a virulent poison, perhaps the summer months would bear a better health record.
One word of warning may not be amiss. Whenever a young child is fed upon cow's milk, and this causes symptoms of disagreement, the diet should be changed at once either to meat or rice; for, if the chief mischief-maker be at work, the best milk will only furnish it with the medium in which it flourishes, and, deprived of this, it will inevitably perish.