Hostname: page-component-848d4c4894-nmvwc Total loading time: 0 Render date: 2024-07-01T16:39:19.915Z Has data issue: false hasContentIssue false

Observations on the growth in nutrient broth of mixtures of Escherichia coli strains, and of faecal specimens harbouring pathogenic Escherichia coli serotypes

Published online by Cambridge University Press:  15 May 2009

J. M. S. Dixon
Affiliation:
Public Health Laboratory, Cardiff
Rights & Permissions [Opens in a new window]

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Experiments were made with five pathogenic serotypes and five non-pathogenic Esch. coli strains to study the competitive growth of mixed coli cultures in nutrient broth. In associations incubated at either 37 or 44°C. the organism inoculated in smallest numbers increased proportionately after 18 or more hours' incubation. The greater the initial disparity, the greater was the increase. Broth culture favoured the pathogenic strains only when these were numerically inferior in the inoculum. The tendency to numerical equation increased with increasing length of incubation.

A study was made of the use of nutrient broth as an aid to the isolation of pathogenic Esch. coli strains from the faeces of infants. 120 positive specimens were examined. Nutrient broth incubated at 44° C. was the most successful method, and when used as a complement to direct plating resulted in an additional 19·6% of positive specimens. The main value of nutrient broth as an enrichment method is in the examination of the faeces of suspected carriers and convalescent patients, in which the pathogen is likely to be outnumbered by non-pathogenic Esch. coli strains.

I wish to thank Prof. Scott Thomson for his advice and helpful criticism, and Dr R. W. S. Harvey for his interest and encouragement.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1959

References

REFERENCES

Cefalù, M. & Brancato, P. (1953). Sull'etiologia colibacillare delle gastro-enteriti infantili con particolare riguardo al gruppo O25. Ann. Sanita pubbl. 14, 671.Google Scholar
Dean, A. C. R. & Hinshelwood, C. (1954). Competitive growth of lactose-positive and lactose-negative strains of Bact. coli mutabile. Proc. roy. Soc. B, 142, 471.Google Scholar
Fulton, M. (1937). Antibiosis in the colon-typhoid group. I. Growth curves of two strains in a synthetic medium. J. Bact. 34, 301.CrossRefGoogle Scholar
Miles, A. A. & Misra, S. S. (1938). The estimation of the bactericidal power of the blood. J. Hyg., Camb., 38, 732.Google Scholar
Thomson, S. (1955). The numbers of pathogenic bacilli in faeces in intestinal diseases. J. Hyg., Camb., 53, 217.Google Scholar
Thomson, S., Watkins, A. G. & Gray, O. P. (1956). Escherichia coli gastro-enteritis. Arch. Dis. Childh. 31, 340.Google Scholar
Topley, W. W. C. & Fielden, H. A. (1922). The succession of dominant species in a mixed bacterial culture in a fluid medium. Lancet, ii, 1164.CrossRefGoogle Scholar