AN IMPROVED ANAEROBE JAR

SEPARATION OF THE TOXINS OF BACILLUS DYSENTERIAE SHIGA

By the suppression, through anaerobiosis, of the exotoxin-producing activity of Bacillus dysenteriae Shiga a pure endotoxin is produced directly from the culture. The duality of the poison of Shiga bacillus is further substantiated by studies on the diffusion of exotoxin, or neurotoxin, and endotoxin, or enterotoxin, by means of collodion sacs, implanted intraabdominally in rabbits or placed in vitro.

STUDIES ON THE NASOPHARYNGEAL SECRETIONS FROM PATIENTS WITH COMMON COLDS

From the foregoing experiments it appears that with the filtered nasopharyngeal secretions from early cases of typical infections common colds in the first 3 to 18 hours of the disease, a similar condition can be transmitted to man. With the unheated but not with the heated secretions from four of six such patients we have succeeded in transmitting an affection indistinguishable from common cold to four men and in two instances the condition was conveyed from the person with the experimental disease to a second individual —in all, therefore, to six supposedly normal subjects. The periods of incubation in the experimental disease varied from 8 to 48 hours. We failed to obtain these results with the filtered secretions from cases of common colds 18 and 20 hours after the onset of symptoms and from a patient with the experimental disease 20 hours after the first symptoms. It would appear that the secretions are more active in the early hours of the affection. We also failed in the two instances in which colds were caused by exposure to the elements, or chilling of the body, and not by definite contact with other cases of common colds. Intratracheal inoculations in rabbits with unfiltered and filtered nasopharyngeal washings obtained from patients with common colds induce no characteristic or distinctive effects on the tissues, from which no constant, pathogenic agent has, as yet, been recovered. In comparison, similar material from cases of epidemic influenza do, however, cause particular changes in the blood and lungs of these animals, cultures of the lungs often yielding Bacterium pneumosintes. In view of these facts and since the clinical pictures exhibited by these diseases differ, the conclusion may be drawn that infectious common colds and epidemic influenza are separate and distinct diseases. On the other hand, the negative results obtained with materials derived from common colds and from parallel series of experiments with secretions from supposedly healthy persons, serve as a control to the effects produced with the nasopharyngeal washings obtained from influenza patients. Aerobic and anaerobic cultures of the filtered nasopharyngeal washings from 40 early cases of infectious common colds have thus far yielded no constant, pathogenic agent which can be regarded as the incitant of the disease. The filtered washings of nineteen cases were studied by the combined method of Smith-Noguchi fluid medium and anaerobic blood agar plates. In these instances representatives of the three groups of anaerobic filter-passing, Gram-negative bacteria, described by Olitsky and Gates were cultured from twelve patients. The irregularity of their occurrence not only in common colds but in influenza and supposedly normal persons and their lack of pathogenicity for rabbits and man indicate that these bacteria are not peculiar to common colds. This method has opened to view a number of hitherto undescribed microorganisms which can be found in different respiratory affections and in health. Furthermore, by morphological, cultural, and serological means, the separation into distinct species of each of these groups of bacteria has again been demonstrated. It is noteworthy that Bacterium pneumosintes was not found in any of the cultures from the 40 patients. Special attention was given to the detection of elements similar to Foster's globoid bodies in the cultures derived from common colds and from the experimental disease in man, and from the lungs of inoculated rabbits. We have not been able to determine the presence of these bodies, although the precipitate which forms in fresh rabbit kidney tissue-ascitic fluid medium was illusory in such relation since it was a common experience to find this precipitate simulating the globoid bodies of poliomyelitis. Still more disturbing is the fact, that these particles could be carried over from subplant to subplant and even showed pseudo colony formation in the Noguchi semisolid medium in tubes. But when the particles were put to rigorous test for a living and multiplying organism, the tests failed to reveal multiplication. The increasing importance of the tissue-ascitic fluid medium in bacteriological technique warrants a detailed description of the requirements necessary for the determination of the living nature of formed elements in cultures in this medium, (a) No one method of staining can be relied upon, for stain precipitate in itself adds to the confusion. A specimen for examination should be stained separately by Gram's and Giemsa's methods and with another nudear dye, such as polychrome methylene blue. As a rule, microorganisms will reveal their morphological characters in more than one stain, whereas precipitate may be found in only one and not in the others. The experienced eye will discern the precipitated particles in selected parts of the stained preparation where they often occur in enormous numbers, clumped into irregular masses of varying forms from the periphery of which there is a gradual fading out to finer, more uniform structures. (b) In addition, suspected growths should be tested in the dialysate medium of Gates since by this method the precipitated material of the medium is kept from admixing with the growth, and a clear view of any microorganisms, if present, is obtained, (c) Another requirement is colony formation of the suspected culture. This is an absolute essential and can be effected by planting the material to be tested on solid plate media, incubated aerobically, and anaerobically in Brown's jar. Semisolid medium in long tubes should also be employed but care is needed to avoid mistaking small particles of precipitate for actual colonies of bacteria. To make certain of growth of microorganisms in semisolid medium, however, subplanting to a precipitate-free, dialysate medium is required. By following this method minute microorganisms which are obscured, or simulated, by precipitate in the Smith-Noguchi medium, can be identified.

STUDIES IN THE COMMON COLD : I. OBSERVATIONS OF THE NORMAL BACTERIAL FLORA OF NOSE AND THROAT WITH VARIATIONS OCCURRING DURING COLDS

1. The normal bacterial flora of the nose and throat of thirteen individuals has been studied over periods ranging from 5 to 9 months. 2. Observations have been made of qualitative and quantitative changes in the flora occurring in the course of colds and of throat infections appearing in the group. 3. The normal basic nasal flora includes Staphylococcus albus, diphtheroids, and for certain individuals Staphylococcus aureus and citreus. Occasional transient bacteria are Gram-negative cocci and non-hemolytic streptococci. 4. The normal basic throat flora includes Gram-negative cocci, non-hemolytic streptococci, and for certain individuals "large Gram-positive cocci," B. influenzæ, Bacillus "X," and diphtheroids. Transient organisms are Staphylococcus albus, hemolytic streptococci,Staphylococcus aureus and citreus, and pneumococci. 5. No bacteria were found in early cold cultures to which a causative rôle could be assigned. 6. In the course of colds the basic flora of the nose was often scanty in the early stages. The throat showed reduction of prominence or alterations in predominance of the basic flora. 7. Certain organisms were prominent in colds, usually as late or secondary invaders, these included Staphylococcus aureus, hemolytic streptococci, and B. influenzæ. 8. There was a striking increase in the incidence of hemolytic streptococci in throat infections.

EXPERIMENTAL STUDIES OF THE NASOPHARYNGEAL SECRETIONS FROM INFLUENZA PATIENTS : VII. FURTHER OBSERVATIONS ON THE CULTURAL AND MORPHOLOGICAL CHARACTERS OF BACTERIUM PNEUMOSINTES

After artificial cultivation for a period of over 3 years Bacterium pneumosintes has maintained its original morphological and cultural characteristics, when grown in the original medium. Adaptation to a saprophytic existence has been accompanied by a loss of pathogenicity. Our strains now grow readily under strictly anaerobic conditions in a variety of media with peptone broth as a base, enriched with fresh tissue, blood, or by the growth of other bacteria. Surface colonies have been obtained on blood agar plates in. an anaerobic jar. These various methods of cultivation are adapted to special purposes. In broth cultures Bacterium pneumosintes grows in larger forms than in the ascitic fluid-tissue medium, but the identity of the microorganisms is proved by their serological reactions and by reversion to the minute forms on transfer to the original medium.

THE INTESTINAL FLORA IN MOUSE TYPHOID INFECTION

The normal flora of laboratory mice at The Rockefeller Institute, fed on a bread and milk diet, was determined. Bacillus acidophilus and Bacillus bifidus outnumber the Bacillus coli, Bacillus acidi lactici, and Bacillus coli communior group about twenty-five to one. White and yellow cocci which may or may not liquefy gelatin are occasionally noted; spirochetal and vibrio forms and yeasts are usually seen in stained preparations. This flora does not change when mice are artificially infected per os with a strain of mouse typhoid bacilli (Bacillus pestis cavice) and is the same in the animals which resist the infection as in those which succumb. Mice fed on a meat diet and showing a colon, Bacillus diffluens, and Bacillus welchii flora do not differ in susceptibility to mouse typhoid from the normal mice fed on bread and milk and showing the above acidophilus flora.

EXPERIMENTS ON THE SURVIVAL OF THE FEBRILE HERPETIC AND ALLIED VIRUSES IN VITRO

These studies fail to confirm the statements previously made that microorganisms of the class of the globoid bodies of poliomyelitis may be cultivated in the Smith-Noguchi medium from the so called virus of encephalitis lethargica. They show equally that the herpes virus does not multiply in this medium. The experiments indicate, moreover, that the medium is unfavorable to the survival of the virus, while ordinary broth under aerobic conditions is more favorable for maintaining the activity of both the encephalitic and the herpes viruses. Probably no multiplication of either takes place in the latter medium but merely a survival, and for a maximum period of 6 days in the broth itself, and 12 days in the fragment of brain tissue immersed in the broth. Finally, it has been shown that with a suitable technique the viruses can be passed from the brain of one rabbit to that of another through a long series without contamination with cocci or other common bacterial forms. Hence we regard all reports of the finding of ordinary bacteria in the brain of cases of epidemic or lethargic encephalitis as instances of mixed or secondary infection arising during life, or examples of postmortem invasion of the body, or of faulty technique at the autopsy.