Bacteria In Media Research Articles

The Effect of X-rays on Bacteria in Media of High Specific Gravity

THE older radiologists undoubtedly have noted improvement in some cases following the injection of Beck's paste into a sinus for radiographic purposes, this being especially true in the years between 1908 and 1915 (1, 2). Less improvement has been noted since the latter date. Coinciding with this transition in the results and, therefore, the use of Beck's paste, there was also a transition going on in our x-ray technic and equipment. With the old gas tube, plates, and no screens, we had to be on constant guard against burning a patient in our effort to secure satisfactory roentgenograms. In other words, at the same time we were making roentgenograms we were actually treating the patient. With the development of the hot cathode tube, films with double emulsion, and intensifying screens, the length of our exposure was very markedly reduced. It is my contention that it was because of this shortened time of exposure that less satisfactory therapeutic results were obtained with Beck's paste. To verify this opi...

THE ISOLATION OF RINGWORM FUNGI FROM SWEAT

Hyperhidrosis is a frequently mentioned etiologic factor in the production of dermatophytosis. In reviewing the literature, however, we found no report indicating the recovery of fungi from the sweat. In the course of our studies on the chemistry and physiology of sweat, we attempted to isolate fungus organisms from specimens of sweat. In undertaking these experiments it was our belief that as sweat is apparently an excellent culture medium, it is therefore probably an active factor in the spreading of infections. This is especially true because sweat, containing as it does water, salt, sugar and nitrogenous compounds, has all the constituents of a good culture medium. In a paper on human sweat as a culture medium for bacteria, Usher¹showed that in the laboratory, fungi as well as bacteria would grow well when inoculated into sterilized sweat. In 1908, Whitfield²reported a case in which the hands of

Detergent Properties of Alkaline Dairy Washing Compounds

TO quote that modern classic Fundamentals of Dairy Science:' While dairy utensils are in no sense a natural habitat of bacteria, a great many organisms grow on the surfaces of such equipment so that the utensils form an important source of bacteria in milk. As a general rule, in fact, under ordinary farm conditions where steam is not available for sterilizing purposes, more bacteria gain access to milk through utensils than from any other sources. These conclusions can truthfully be supplemented with the observation that the farmer is not the only offender in this matter. Some of the present methods of dairy sanitation fail to give cleanliness consistent with quality standards. Cleanliness is the exception and not the rule. The presence of oily films in pipe lines, utensils, pasteurizers, holding and mixing tanks, valves and the like, can readily be detected by the finger. Wherever intense heat (particularly steam) is applied to any surface in contact with milk for an appreciable period of time, a calcareous deposit known as milk stone forms, which continued applications of some washing compounds fail to remove. Such surfaces are not clean and can be the sources of trouble because they provide culture medium for bacteria which may gain access between the washing and sterilizing and the passage of fresh milk. When such conditions become troublesome, it is sometimes the practice to apply copious amounts of some chlorine disinfectant, which may be antiseptic for short periods but never germicidal, since their disinfecting properties are destroyed through chemical combination with the adhering milk solids, and the condition remains to cause future trouble. These statements, however, must not be interpreted as a condemnation of the use of chlorine disinfectants, but rather as a warning for their intelligent application. These failures to obtain cleanliness certainly are not due to dairy

Reduction of Sulphites by certain Bacteria in Media containing a Fermentable Carbohydrate and Metallic Salts

(1) In media containing sodium sulphite, glucose, and iron salts, reduction of sulphite to sulphide is effected by B. typhosus, B. enteritidis (Gaertner), B. paratyphosus B, and various other members of the Salmonella group. No reduction was shown by B. paratyphosus A, and the various dysentery bacilli.(2) The use of certain media containing sodium sulphite is recommended in attempting to’ isolate typhoid and paratyphoid B bacilli from excreta, water, milk, etc.(3) It is suggested that the blackening which is brought about by certain members of the Typhoid-Paratyphoid-Enteritidis group in nutrient agar containing lead acetate is due, at least in part, to the reduction of sulphite im purities and that in order to get constant results with different brands of peptone an addition of sodium sulphite and a suitable fermentable carbo hydrate should be made to the medium.

The Number and Varieties of Bacteria carried by the Common House-fly in Sanitary and Insanitary City Areas

1. Over 450 naturally infected or wild flies (Musca domestica) were caught in Liverpool during September and the first part of October 1911 from different parts of the city. The number and kinds of bacteria carried and contained by them have been investigated.2. The number of bacteria coming from house-flies whilst struggling in liquid may be very large, varying from 2000, the lowest figure in 5 minutes, to 350,000, the highest figure in 30 minutes. This number may be taken as a measure of their capacity to pollute liquid with their vomit or excrement, or by wallowing in it. The number of bacteria carried inside the fly is very much greater.3. Flies caught either in insanitary or congested areas of the city carry and contain far more bacteria than those from the more sanitary, less congested or suburban areas. The number of aerobic bacteria from the former varied from 800,000 to 500,000,000 per fly, and from the latter from 21,000 to 100,000.4. The number of intestinal bacteria as indicated by glucose bile salt fermenters is also greater in the insanitary or congested areas, the numbers varying from 10,000 to 333,000,000, than in the more sanitary areas where they carried from 100 to 10,000.5. Pathogenic bacteria and those allied to the food poisoning group were only obtained from the congested or moderately congested areas and never from the suburban areas.6. We have examined the morphological characters and cultural reactions of 123 strains. Among those identified were twoStreptococci, and severalStaphylococciandSarcinae. 106 were small Gram negative non-spore bearing bacilli, and have been grouped as follows:Chromogenicgroup. Two strains ofB. pyocyaneuswere isolated from a knacker's yard; for the first time, we believe, from wild flies.Colon group. 41 colonies of this group were picked off haphazard and classified according to McConkey as follows:B. acidi lacticitype 19·5%B. coli communistype 12·2 %B. neapolitanustype 19·5 %B. lactis aerogenestype 46·4 %Salmonella group. One bacillus gave identical reactions toB. enteritidisof Gaertner except that serological tests were negative.Morgan's infantile diarrhoea group. One identical to Morgan's No. 1, and many others closely resembling it and Morgan's Nos. 2 and 3 were obtained.Others fall into Proteolytic, Acid lactose-sucrose (saccharose), and Miscellaneous groups.7. Flies caught in milk shops apparently carry and contain more bacteria than those from other shops with exposed food in a similar neighbourhood. The reason of this is probably because milk when accessible, especially in the summer months, is suitable culture medium for bacteria, and the flies first inoculate the milk and later reinoculate themselves, and then more of the milk, so establishing a vicious circle.8. On one occasion we compared the number of bacteria carried by house-flies caught in an eating house opposite the slaughter houses with the number carried by blue-bottles; the latter, as might be expected, was far larger.9. In cities where food is plentiful flies rarely migrate from the localities in which they are bred, and consequently the number of bacteria they carry depends upon the general standard of cleanliness in that locality. This is well indicated by the fact that flies caught in a street of modern fairly high class workmens' dwellings forming a sanitary oasis (Hornby Street) in the midst of a slum area, carried far less bacteria than those caught in the adjacent neighbourhood.10. It is clear that flies from the suburbs where infantile diarrhoea is rare carry far less bacteria than those in the city where it is common. It was, nevertheless, impossible in the time at our disposal to correlate exactly the number or varieties of bacteria carried by flies in the city with the number of cases and deaths from infantile diarrhoea in individual streets.11. As the amount of dirt carried by flies in any particular locality, measured in terms of bacteria, bears a definite relation to the habits of the people and the state of the streets, it demonstrates the necessity of efficient municipal and domestic cleanliness, if the food of the inhabitants is to escape pollution, not only with harmless but also with occasional pathogenic bacteria.