The Measurement of Bacterial Virulence and of Certain Allied Properties, with special reference to the Virulence of<i>B. aertrycke</i>.

Lockhart, Leonard P.

doi:10.1017/s0022172400017204

Cited by 15 publications

(11 citation statements)

References 20 publications

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“…Webster (5) failed to show any rise in virulence. Lockhart (6) concludes that the virulence of a single strain of B. aertrycke may be significantly increased as the result of animal passage, but in the text he admits that such increase cannot be brought about with any regularity. A prolonged experience of one of us with the hog cholera bacillus since 1885 leads to the conclusion that passages tend downwards rather than upwards in capacity to kill.…”

Section: Discussionmentioning

confidence: 99%

Studies on a Paratyphoid Infection in Guinea Pigs

Smith

Nelson

1927

Journal of Experimental Medicine

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Factors bearing on the maintenance of paratyphoid in an endemic state are discussed. There was no evidence of any increase nor any dearly demonstrable proof of a decline in virulence of the causative organism. This persisted within the breeding stock and it is suggested that the sows constituted the chief focus for dissemination of the organism to their young and from these to the population at large. Evidence is presented that the carriage of B. paratyphi in the feces was of relatively short duration. Fecal carriage of B. paratyphi was commonly associated with a localization of the organism in the spleen. Since it is obvious that some factor or factors must have changed in the transition from epidemic to endemic phase in the presence of younger generations, the hypothesis is tentatively presented that the transition from epidemic to endemic phase is due to a combination of the weeding out of individuals of low natural resistance with a gradual adjustment of the invading organism to the population on a lowered level of virulence.

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Section: Discussionmentioning

confidence: 99%

Studies on a Paratyphoid Infection in Guinea Pigs

Smith

Nelson

1927

Journal of Experimental Medicine

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“…There are at least two culture tests made for each group which will give some appreciation of this factor, however. Cultures before peak of epidemic were 1, 4, 11, and 12; at peak 6,13,15,16,17,18,19,32, and 33, and in the interepidemic period were 34 and 50. The material is set out below: "The variation between tests is greater than that within tests, as in the previous results for Strain 1.…”

Section: Test 2 the Virulence Of Freshly Isolated "Epidemid' Strainsmentioning

confidence: 97%

The Mode of Spread of a Friedländer Bacillus-Like Respiratory Infection of Mice

Webster

1928

Journal of Experimental Medicine

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A spontaneous respiratory disease of mice incited by Friedländer like bacilli has been described. The bacilli inducing the disease, while morphologically and culturally indistinguishable from the usual varieties of Friedländer bacilli, are antigenically distinct from the common type strains known. The bacilli grow better in cultures at 23°C. than at 37°C. The disease in mice displayed an incubation period of about 48 hours. About 50 per cent of an exposed population succumbed to septicemic and acute hemorrhagic, pneumonic processes. Among the exposed animals were some individuals which remained apparently well and carried the pathogenic bacilli in their nasal passages. The several manifestations of the spontaneous disease were reproduced by instilling small numbers of the cultured bacilli into the nasal passages. 48 hours after inoculation, certain mice had already succumbed; the deaths continued to occur, so that by the end of the 2nd week, 70–80 per cent of the animals had died. Among the survivors certain carriers of the bacilli in the nasal passages occurred; a few appeared entirely refractory to the infection. The succumbing mice showed at autopsy and by culture septicemia and diffuse pneumonic inflammation. No fluctuation in virulence could be detected in bacilli derived from mice while the disease was spreading spontaneously at the periods of epidemic rise, interepidemic interval, or postepidemic quiescence. Moreover, the bacilli cultured from the nares of apparently healthy carriers were equally pathogenic with those taken from the blood and lungs of animals succumbing quickly. No rough colony variants were cultured at any phase of the spontaneous disease, although they were readily obtainable by artificial culture. The variant strains proved stable and of low virulence. This Friedländer bacilli infection in mice takes several clinical courses, depending on variations in host reaction and not depending on bacterial variation. The particular type of infection manifested is determined by the degree of resisting power displayed by the infected animals at the moment that the infection occurred and progressed.

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“…That variations do occur in cultures of S. aertrycke apparently spontaneously as well as under specific changes of treatment has been shown by LOCKHART (1926) and WILSON (1928, 1930, 1931). However, certain strains of the organism have been observed to maintain a high virulence over many years of culture on laboratory media.…”

Section: Virulence Of the Organismmentioning

confidence: 62%

“…144-147, andSAVAGE 1925). LEY and his associates have carried on extensive epidemiological and virulence studies with this organism using the mouse as the host (TOPLEY 1925, LOCKHART 1926, WILSON 1930. A stock of the organism used in the Genetics Laboratory is carried in the American Type Culture Collection, JOHN MCCORMICK INSTITUTE, listed under material supplied by M. R. IRWIN, 1926, as S. aertrycke, No.…”

Section: Methodsmentioning

confidence: 99%

The inheritance of resistance to Salmonella aertrycke in various strains of mice

Schott

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The Measurement of Bacterial Virulence and of Certain Allied Properties, with special reference to the Virulence ofB. aertrycke.

Abstract: In connection with recent investigations on the spread of bacterial infection among mice, the possible effect of variations in the virulence of the infecting organism has, inevitably, formed one of the problems for study.

Cited by 15 publications

References 20 publications

Studies on a Paratyphoid Infection in Guinea Pigs

Studies on a Paratyphoid Infection in Guinea Pigs

The Mode of Spread of a Friedländer Bacillus-Like Respiratory Infection of Mice

The inheritance of resistance to Salmonella aertrycke in various strains of mice

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