Growth of salmonellas in different enrichment media

Abstract

The usefulness of selenite-F (S-F), tetrathionate (MKT) and Rappaport-10 (R-10) broths as enrichment media to support growth of salmonellas either alone or in the presence of other competing organisms was studied. Their ability to support the growth of stressed salmonellas from water was also investigated. It was observed that R-10 was more inhibitory to competing organisms than MKT and S-F. It strongly inhibited the growth of Pseudomonas aeruginosa, Citrobacter freundii and Proteus vulgaris though not of Escherichia coli and Enterobacter aerogenes. It was more toxic, however, to small numbers of salmonellas than MKT and S-F. Tetrathionate was strongly inhibitory for E. coli and Ent. aerogenes but much less so for Proteus and Pseudomonas species. Selenite-F was much less inhibitory than MKT to Ps. aeruginosa and it did not inhibit growth of E. coli and Ent. aerogenes as much as MKT. Salmonellas were inhibited by all three enrichment media and none of them is ideally suited for direct use. Of the three media, R-10 was much more inhibitory to stressed organisms than S-F or MKT.

Comparison of Four Chromogenic Media and Hektoen Agar for Detection and Presumptive Identification of Salmonella Strains in Human Stools

“…However, enrichment broth may be toxic for some Salmonella strains (21), as was the case for one of the isolates found in this study. Moreover, direct plating identified serovar Enterica in about 50% of cases, 1 day earlier than would have been possible if only selenite enrichment broth had been inoculated on day 1.…”

Efficiency of different enrichment and isolation procedures for the detection of Salmonella serotypes in edible offal

“…However, according to Van Schothorst et al (1977), inhibition depends less upon the serotype than upon the sensitivity of certain cells to the inhibitor. Patil and Parhad (1986) reported that T T B was the best enrichment medium when E. coli and other lactose-positive Enterobacteriaceae were the predominant competing organisms, whereas SC yielded better results when organisms of the genus Proteus predominated.…”

Evidence that a Metabolic Microcompartment Contains and Recycles Private Cofactor Pools

“…Together, these genes constitute nearly 2% of the Salmonella genome and encode proteins for catabolism of ethanolamine and 1,2-propanediol, synthesis of B 12 (cob and cbi), and use of tetrathionate as an electron acceptor (ttr, phs, asr) (11,44,45). These genes are found in all Salmonella isolates and were used individually as taxonomic criteria for identifying Salmonella even before it was clear that they acted together (46,47). Recent results show that this constellation of genes allows Salmonella to grow in an inflamed gut (34, 43) using two poor carbon sources (ethanolamine and 1,2-propanediol).…”