A study of isolation procedures for multiple infections of Salmonella and Arizona in a wild marsupial, the quokka (Setonix brachyurus)
- 1 December 1982
- journal article
- research article
- Published by Wiley in Journal of Applied Bacteriology
- Vol. 53 (3) , 395-406
- https://doi.org/10.1111/j.1365-2672.1982.tb01288.x
Abstract
Rectal swabs and faeces were used in the regular sampling for salmonellas and Arizonas from a heavily‐infected population of a marsupial, the quokka (Setonix brachyurus). The media used were strontium selenite A and strontium chloride B enrichment broths, with subculture onto modified bismuth sulphite agar and deoxycholate citrate agar. A study of sampling, enrichment, sub‐culture and colony selection procedures produced an optimal scheme giving high yields but consistent with reasonable economy of time and materials. A three‐swab sample was taken and inoculated into the two enrichment media, and with each enrichment subjected to three subcultures. The absolute efficiency of this procedure was greater than 80% (and confirmed by a serological method), compared with only 67% for a single swab in a single enrichment. Recovery of some serotypes depended on the media used; e.g. Arizonas could not be recovered satisfactorily from strontium chloride B enrichment. Faeces samples were found to be greatly superior to rectal swabs for detecting salmonellas and arizonas but they were less convenient in field studies. In a comparison of rectal swabs and faeces samples where the actual concentration of salmonellas was known, it was found that the efficiency of rectal swabs approached 100% if there were more than 103 salmonellas/g faeces, but this declined to approximately 50% if there were 102‐103 salmonellas/g faeces and only 25% if there were less than 102 salmonellas/g faeces. A new statistical procedure was introduced for comparing the number of isolations from two methods, and this should be of use in similar methodological studies.This publication has 14 references indexed in Scilit:
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