Abstract
Factors and techniques leading to the more rapid isolation of salmonellae from faeces that are negative by direct plating were examined. The aim was to increase the number of specimens on which positive reports might be given within 24 hours of receipt. Salmonellae were isolated from 279 of the specimens studied.
Brilliant green MacConkey agar was found to be the most satisfactory solid selective medium both for direct plating and as a subculture medium, giving large characteristic colonies after 24 hours' incubation. Selenite F medium, inoculated with undiluted faeces, incubated at 43°C., and subcultured after six hours' incubation on to brilliant green MacConkey agar, was the most successful rapid method of enrichment, though the results were considerably inferior to those obtained after 24 hours' incubation. Seventy-six of the positive specimens examined were negative by direct plating on three different selective media; 24 (31·6%) of these were positive on subculture from selenite F incubated for six hours at 43°C. and 21 (27·6%) when incubation was at 37°C. The use of six-hour subcultures from 43°C. selenite F as a supplement to direct plating added significantly to the number of positive results. Other techniques that were tried but found to be of no practical value were dilution of the faeces before inoculation on solid and fluid media, and replica plating from one solid medium to another after a few hours' incubation.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BANWART G. J., AYRES J. C. Effect of various enrichment broths and selective agars upon the growth of several species of Salmonella. Appl Microbiol. 1953 Nov;1(6):296–301. doi: 10.1128/am.1.6.296-301.1953. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HARVEY R. W. Choice of a selective medium for the routine isolation of members of the Salmonella group. Mon Bull Minist Health Public Health Lab Serv. 1956 Jun;15:118–124. [PubMed] [Google Scholar]
- KONFORTI N., NAVON B., RAPPAPORT F. A new enrichment medium for certain Salmonellae. J Clin Pathol. 1956 Aug;9(3):261–266. doi: 10.1136/jcp.9.3.261. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LEDERBERG J., LEDERBERG E. M. Replica plating and indirect selection of bacterial mutants. J Bacteriol. 1952 Mar;63(3):399–406. doi: 10.1128/jb.63.3.399-406.1952. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SMITH H. G. On the nature of the selective action of selenite broth. J Gen Microbiol. 1959 Aug;21:61–71. doi: 10.1099/00221287-21-1-61. [DOI] [PubMed] [Google Scholar]
- SMITH H. W. The evaluation of culture media for the isolation of salmonellae from faeces. J Hyg (Lond) 1952 Mar;50(1):21–36. doi: 10.1017/s0022172400019409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- THOMSON S. The number of bacilli harboured by enteric carriers. J Hyg (Lond) 1954 Mar;52(1):67–70. doi: 10.1017/s0022172400027261. [DOI] [PMC free article] [PubMed] [Google Scholar]