Edwin O. Jordan

The Kinds of Bacteria found in River Water.

1. The kinds of bacteria that are isolated by the gelatin plate method from certain river waters freshly polluted with sewage are different from those found in the same water collected a long distance below the point of pollution. 2. In the freshly polluted river water non-chromogenic Staphylococci were found much more abundantly than in the purer waters. 3. In the freshly polluted water the fluorescent bacteria and a group of non-gas-producing, non-liquefying bacteria (Group XI.) were less abundant than in the purer waters. 4. A larger proportion of organisms belonging to the Proteus group were isolated from gelatin plates than from fermentation tubes. The reverse is true of the B. coli and B. lactis aerogenes types. A certain selective influence even upon gas-producing organisms would seem from this to be exerted by the conditions within the fermentation tube. 5. The study of a rather large number of separately isolated cultures belonging to the class of fluorescent microorganisms shows that the differences between the ‘liquefying’ and ‘non-liquefying’ varieties are more constant than is sometimes assumed. The action of these forms upon milk is just as diagnostic as their action upon gelatin. All the strains of fluorescent bacteria that were encountered (58) proved to be motile. 6. Considering as a whole the various physiological tests applied to the several groups of microorganisms, it is found that within almost every group as constituted in the accompanying tables divergence is shown by closely allied organisms in respect to indol formation and reduction of nitrates. The formation of a surface pellicle on broth is also a phenomenon that presents no apparent correlation with more s alient physiological characteristics.

Nature of the Substance Causing Staphylococcus Food Poisoning

The difficulties experienced in studying staphylococcus food poisoning when the only available subject for experimentation was the human volunteer have been in part overcome by the observation that monkeys can be fed staphylococcus filtrates in such a way as to insure a certain proportion of definite and characteristic gastrointestinal reactions. 1 Utilizing monkey feeding as a crude method of determining the presence or absence of the significant principle, some data bearing on the nature of this principle have been obtained. In all the tests here reported only animals showing actual vomiting have been set down as yielding a positive reaction; other symptoms such as pallor, diarrhea, and evident distress have been noted but not recorded as indicating an unmistakable positive result. Not all monkeys react to the active principle inducing vomiting and consequently, before using an animal for experiment we have fed it with a filtrate of known potency. Negative results were controlled by subsequent feeding with potent filtrate. The possible development of tolerance has also been controlled. The following results have been obtained: 1. The active principle will not distill. 2. It is not readily dialyzable. 3. It is markedly unstable to N/100 NaOH. 4. It is unstable to heat in N/100 HCl solution. 5. It is not identical with the hemolytic substance present in many staphylococcus filtrates nor does it produce a skin reaction. 6. It is completely removed from acid aqueous solution by extraction with ethyl ether or chloroform as judged by our method of assay. 7. It may be extracted from alkaline solution with ethyl ether or chloroform but the deleterious effect of alkali tends to mask such removal. Feeding with a neutral saline or aqueous solution of the ether or chloroform extracts from which all traces of the solvent had been removed by warming in vacuo caused typical vomiting in monkeys.

Influence of Age on Amount of Normal Agglutinins in the Blood of Cattle

The currently accepted explanation of the frequent presence in normal human adults, as contrasted with young children, of antibodies such as diphtheria antitoxin and the substance that neutralizes the virus of poliomyelitis, is that the antibodies have been specifically generated by an unnoticed or a subclinical infection. The occurrence of normal bacterial agglutinins in the blood of various adult domestic animals, as demonstrated by Burgi, Gibson and others, has suggested some observations upon the influence of age on the presence and abundance of these antibodies. These agglutinins are common in the blood of cattle, they are specific at least to the extent of being removed by absorption with specific bacterial cells and they comprise both the H and O antigenic types. The standard macroscopic agglutination technique was used. The serum was freshly obtained from cattle brought to the Chicago stockyards, and was from 3 groups: (a) calves (under 1 year); (b) heifers (approximately 1-2 years); (c) “cows and steers”. The table shows, as observed by others, that there is considerable variation in the amounts of agglutinins for different bacterial strains, and without exception, agglutination is greater, often in a very striking degree, in the serum of the older animals than in that of the calves. The animals classed as heifers appear to have about the same amount of bacterial agglutinins in their blood as the older animals, but the titers average somewhat lower. There also appears to be a sex difference, for simplifications sake not indicated in the table. The serum of females contains on the average a distinctly greater amount of agglutinins than that of males. Some observers have used strains of the Salmonella group to test for the presence of normal agglutinins. 1

The Rôle of Staphylococci in Food Poisoning.

In food poisoning of the gastrointestinal type attention has been previously focused chiefly on the Salmonella (paratyphoid-enteritidis) group of bacilli. Some European observers have been unwilling to attribute etiological significance to any other organisms. During the past few years, however, material from a number of well defined food poisoning outbreaks, apparently of bacterial origin, has been subjected to thorough bacterial examination in our laboratories without being found to contain any paratyphoid bacilli. I have consequently become convinced that in a considerable number of cases some other bacterial factor is involved. A recent outbreak in Chicago in which a yellow staphylococcus was found by Dack and other workers 1 in this laboratory to be the probable causal agent has led me to carry out some observations on other staphylococcus strains. With the aid of human volunteers the sterile filtrates of 6 staphylococci have been tested. From 5 to 10 cc. of sterile broth filtrates of these organisms taken by mouth has caused in a few hours the train of food poisoning symptoms commonly met with: dizziness, loss of appetite, nausea, vomiting and diarrhea. These staphylococci are of diverse origin and are not of uniform cultural character. Three of these were isolated from normal human throats, one from a case of septicemia in man and 2 from food implicated in “food poisoning” outbreaks. With the amounts of filtrate used not all volunteers were affected, but out of 34 taking approximately the same quantity 26 became definitely ill with characteristic symptoms. Eleven control subjects taking the same food at the same time without addition of filtrates remained well, but one reported the occurrence of food poisoning symptoms. Since this individual had been made quite ill with filtrates the previous week, the second attack may have been due to suggestion or to association with those who were ill.

Notes on Intestinal Flora In the Tropics.

The relative frequency of intestinal disorders in tropical countries, the multiplicity of microorganisms to which a causal relation has been attributed, the uncertainty prevailing about the distribution and significance of such bacteria as the Morgan bacillus and various Salmonella types and the general lack of knowledge about the etiology of tropical intestinal disease combine to give to even fragmentary observations some degree of value in guiding further research. In the course of various studies on other matters in Puerto Rico and in the Panama Canal Zone, we have gathered a few data upon intestinal flora which it seems worth while to place on record. 1 Enteritis and diarrhea are common in Puerto Rico. On this island in 1930 (January to March), 144 fecal specimens were examined by the poured plate method; these specimens were derived from 81 persons. They were distributed as follows.

THE INFLUENZA EPIDEMIC OF 1918: III

Following the analogies suggested by the successful use of prophylactic inoculation against typhoid and some other infections, a similar method was employed to some extent against influenza. The swift onrush of the pandemic, however, left little time for the preparation and development of methods. In some instances the height of the outbreak had passed before prophylactic inoculation was completed or even initiated. In certain localities pure culture vaccines were used; in others, mixed cultures of several bacterial species. For these and other reasons comparable data, indeed valid data, are not abundant. The primary uncertainty as to the nature of the true causal agent was and is a decisive factor. It seems desirable to discuss some of the conditions that determine the reasonableness of conclusions drawn from attempts at protective inoculation (cf., also, McCoy 1919). Other parts of this summary contain many examples of factors that affect the attack rate

THE BACTERIOLOGY OF FOODS

While the bacterial examination of water in this country has led for some years past to fairly uniform results and has given information of the highest value for estimating the sanitary quality of a water, the bacterial examination of foods and its interpretation have been followed in many cases by a conflict of competent opinion and by a confusion of official and semiofficial rulings that have caused some bewilderment. A brief survey of the situation may be useful in drawing attention to certain points at issue. It will be recognized that the value of bacterial food examination has definite limits. Actual discovery of pathogenic bacteria in food is a rare occurrence, and in particular cases may have little or no practical significance. Few workers would think of advocating a routine bacterial examination for the purpose of ascertaining whether or not specific articles of food can safely be eaten. Milk, the

THE BACTERIOLOGY OF FOODS-Reply

This letter was referred to Professor Jordan, who replies: To the Editor: —It is difficult even with careful phrasing to avoid expressions that, when taken from their context, may be liable to misinterpretation. I had supposed that the statement to which exception is taken was sufficiently guarded to prevent all misunderstanding. Certainly the general tenor of my address is in no wise antagonistic to the proper use of bacterial counts in controlling public milk supplies. My own position in this matter is generally known, as is shown indeed by the quotation from my book cited in the foregoing letter. Let me state once more specifically and emphatically that I believe that bacterial milk counts are a valuable aid in controlling the quality of milk supplies and that their application by municipal authorities has helped to bring about a great improvement in the public milk supplies of American cities. A certain