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CHOLERA, PLAGUE, SMALLPOX, TYPHUS FEVER, AND YELLOW

FEVER—Contin tied.

Reports Received from June 30 to August 10, 1923—Continued.
TYPHUS FEVER—Continued.

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CHOLERA, PLAGUE, SMALLPOX, TYPHUS FEVER, AND YELLOW

FEVER—Continued.

Reports Received from June 30 to August 10, 1923—Continued.
TYPHUS FEVER—Continued.

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PUBLIC HEALTH REPORTS

VOL. 38 AUGUST 24, 1923 No. 34

THE NOMENCLATURE OF THE MELITENSIS-ABORTUS GROUP OF BACTERIAL ORGANISMS.

By Alice C. Evans, Associate Bacteriologist, Hygienic Laboratory, United States Public Health Service.

There is so much confusion in the nomenclature of the melitensisabortus group of bacterial organisms that a brief consideration of the various names that have been applied, together with conclusions as to the generic and specific names which appear to be available and valid in the light of recent investigations, is a necessary preliminary step to the publication of reports of further investigations of this subject.- _

The first report of the isolation of cultures of the group of organisms under consideration was by Bruce in 1887.1 He obtained the specific germ, upon autopsy, from the spleens of human cases which had died of undulant fever on the island of Malta. It was not until 1893, however, when he published a more complete description of his organism, that he named it "Micrococcus mditensis."

Durham (1898) appears to have been the first writer to note that a bacillary form also occurs. He believed that conditions of temperature and medium determined whether the forms would be coccoid or bacillary.

Eyre (1912) mentions the fact that some investigators consider the organism a real "bacillus." He explains the rodlike forms as involution forms, however, or as dividing cocci between which the separation is not yet complete.

The generic name "Bacillus" for the Malta fever organism has been used by Jordan in his "Textbook of General Bacteriology" since the third edition, which appeared in 1912. The majority of American textbooks, however, have clung to the name "Micrococcus mditewis," although all investigators who have studied the organism in recent years have agreed that it is a rod form.

Brace's choice of the generic name "Micrococcus" is explainable. In the Hygienic Laboratory collection of 19 strains from human sources there are 3 for which the geographical source is not accurately known, but circumstantial evidence indicates that two of them, possibly all three, were originally obtained on the island of Malta. The history of these strains is as follows:

1 Bibliographic references are given at the end of this article. KOS-23 1 (1943)

Strain 102 was obtained in December, 1907, from England. According to the record it was labeled "M. melitensis, Dr. Annett." Strain 103 was obtained from the Royal Army Medical Corps of London, England, in January, 1908. It was labeled "M. melitenms, R. A. M. C." Colonel Bruce, R. A. M. C, the discoverer of the Malta fever organism, was the chairman of the British Commission for the Investigation of Mediterranean Fever, which made its report of the investigation on the island of Malta during the years 19051907. It appears very likely that these two cultures, received from England a few months subsequent to the publication of the final report of the commission, were obtained on the island of Malta. There is no record of the origin of the third strain, No. 10-4, other than that it was obtained from the United States Naval Medical School in 1909. The fact that the strain is identical with strains 102 and 103, according to ovefy test that has been applied, suggests that possibly this strain, also, may have been collected in Malta.

The three strains under discussion consist almost entirely of coccoid cells. They present quite a different appearance from the remaining strains in which distinct rod forms are evident at a glance, scattered among the coccoid cells. In this connection it should be noted that the illustration accompanying Bruce's description of his organism corresponds with the three strains of predominating coccoid cells. Most of the cells of these strains (102, 103, 104) are, in Bruce's own words, "round or slightly oval," with only an occasional distinctly elongated form. Serologically, also, the three of our coccoid strains belong to a distinct type, as shown by the agglutinin absorption reactions.

It appears most probable that Bruce was working with strains which wore of peculiar morphological type, as judged by the morphology of the majority of the 19 strains in our collection. If the morphology of the species were to be judged by these three strains alone, it might still be considered a "Micrococcus." There is no question, however, that they belong to the same species as the more common strains in which the bacillary forms are more predominant, for strains of both morphologies are identical in cultural and biochemical reactions, and they can not be differentiated by the simple agglutination reactions.

In 1918 the present author made the observation that there is a very close relationship between the Malta fever organism and the so-called "Bacillus aborttis" which Bang, in 1897, had established as the cause of contagious abortion in cattle.

The generic name "Bacillus" which formerly had been applied promiscuously to all rod forms of bacteria, was no longer in conformity with the nomenclature adopted by the Society of American Bacteriologists, since the Committee of the Society of American Bacteriologists on Characterization and Classification of Bacterial Types, in its 1917 report, restricted the generic name "Bacillus" to aerobic spore-bearing rods. The nonspore-bearing pathogenic rod forms were classified in the genus "Bacterium." Thus "Bacillus abortus" became "Bacterium abortus," ' and the closely related " Micrococcus melitensis" became "Bacterium melitensis." Following the writer's observations that the causal agent of Malta fever in man and that of contagious abortion in cattle are closely related, and that the so-called "Bacillus bronchisepticus"—the cause of distemper in dogs and of a similar disease in other animals—resembles them morphologically, culturally, and biochemically, the Committee suggested (1920) that if these observations were confirmed the mentioned organisms should probably constitute a new genus, because they differed so widely from the type species of the genus Bacterium.

That the Malta fever and contagious abortion organisms are closely related was confirmed by Fleischner, Meyer and Shaw in 1919, and later by a number of other investigators. Meyer and Shaw (1920) proposed the generic name "Brucella," in the family Bacteriacese, to include the Malta fever and contagious abortion organisms. That name has met with general approval, and has been used by foreign investigators (Khaled, Archibald).

Meyer and Shaw did not, however, give a generic diagnosis for the genus Brucella, and they did not consider other species besides the mclitensis-abortus group which would logically belong to the new genus. They were apparently unaware that Castellani and Chalmers had already described a newly created genus, "Alkaligenes," which, according to its definition, would include the melitensis-abortus group. The definition is as follows: "Bacillaceae growing well on ordinary laboratory media; not forming endospores; aerobes, and often faculative anaerobes; without fluorescence, pigment formation, or gelatin liquefaction; without polar staining; Gram-negative, without a capsule * * *. Milk not clotted; glucose and lactose not fermented." The type species of the genus "Alkaligenes" as established by "original designation," is A. fsecalis, a common intestinal saprophyte. Castellani and Chalmers left the "Micrococcus melitensis" unclassified generically—"Incertx sedes"—because they were doubtful as to whether it should be considered a coccus or a rod form.

1 In its final report on the families and genera of the bacteria (J. Bact. 1920, S: 191-229), the Committee changed the specific name "abTrtut" to "abortum," presumably to have the ending agreo with Bacterium. This was an error, for aborttu is not an adjective, but a Latin noun in the genitive of the third declension. Hence its ending is independent of the ending of the generic name.

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