VARIABILITY OF BACTERIA CULTURAL STUDY OF MUTA'TION .' Experiments with Museum Strain of C. enzymicus (Mellon).... Effect of Various Mediums on Selection of Type Zl Experiments with Mellon Strain cultivated on Blood Medium.. STUDY WITH PURE LINE OF C.
work done in this group reveals the fact that there are bacteria which resemble the true diphtheria organism morphologically and culturally, but which differ in one important respect, namely, that of virulence as tested on guinea-pigs. The true Klebs-Loeffler has been shown to ferment dextrose, maltose and dextrin with acid production and to possess definite toxic properties on injection, resulting in the death of the animal in [3][4] days with a characteristic inflammation and congestion of the suprarenal glands. To those bacteria which lack this virulence but which otherwise conform to the character of true diphtheria bacteria, should be assigned the species designation ''pseudodiphtheria."The generic name given to the group by Lehmann and^eumann is Corynebacterium and should be retained for the organisms of this group.Certain characters ought to be accepted as properly belonging to the species before we can adequately define what we mean by a diphtheroid.These may be enumerated as follows : Morphological resemblance to diphtheria organism, gram-positive, nonmotile, absence of spores, presence or absence of metachromatic granules, no gas-production in carbohydrate mediums. The fermentation of sugars may or may not occur. This property gives us a basis for classification which will be taken up later. A careful study of the different species which have been described shows that the characters enumerated ought rightly to be accepted as a basis for differentiating the diphtheroids from other bacteria which have been improperly classed with them. With this end in view the different species are taken up individually and examined from the standpoint of validity and priority. The suitability of the name is considered from the viewpoint of sufficient description, and in the light of more comprehensive studies which have given us suggestions for proper nomenclature. When the species name implies etiology which is unknown, doubtful or unconfirmed, that part of it is modified to suit the case. Historical Review of Diphtheroids and EmendationsThe description is given as follows : Gram-positive, no polar bodies, nonmotile.Grows luxuriantly on blood serum with a glistening layer. In broth clouding is produced. LoeiBer described a pseudodiphtheria organism in his first paper on the etiology of diphtheria. He said the organism resembled diphtheria but was avirulent for guinea-pigs ; that it was smaller than the true diphtheria and showed a marked absence of club-shaped forms. In 1888, V. Hofmann published an account of avirulent diphtheria-like organisms isolated from the oral cavity in 26 of 45 normal persons. He called these organisms pseudodiphtheria bacilli and described them as follows : Clouding produced in broth, no acid production, grow at room temperature, no spores. Diphtheroid Organisms 9The rightful name for this species is Corynebacterium pseudodiphtheriticum (Hofmann-Wellenhof). It is questionable, however, if we can retain this name for all diphtheroids which are morphologically and culturally like the one descri...
In 1918, the writer showed that a simple yeast medium (extract of baker's or brewer's yeast) could be used for prolonging the viability of the meningococcus. The medium possesses the advantages of requiring no meat infusion or meat extract or peptone. It is prepared with agar as a base and is to be used in the solid or semi-solid form. Observations at the time were extended over a period of six, and in several instances over a period of eleven weeks. More than twenty strains of meningococcus, recent and old, representing normal, irregular and para types isolated from the spinal fluid and the nasal mucosa, were tested on the solid medium and were found fully viable after iix weeks on the average and for some strains which were observed eyond that time, for eleven weeks, when stored at 37°C. At
1. 52·6% of marmots placed in contact with marmots infected with plague by inhalation developed pulmonary plague and died within 4–6 days.2. Marmots suffering from pneumonic plague are infective at an early stage of the disease and the animals which such marmots infect acquire plague after a short incubative period.3. Pulmonary plague can be readily transmitted to the small marmot (Spermophilus citellus Linn.), and these animals, when suffering from pulmonary plague, are in turn capable of transmitting the same type of plague through the respiratory passages.4. Septicaemic plague can be developed in marmots very easily as a result of respiratory infection and also by direct subcutaneous inoculation with small amounts of culture.5. The marmot can acquire plague by way of the alimentary tract and spread the disease by feeding on plague-infected carcases. The histological appearances observed in the lesions of these cases are characteristic.
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