Journal of Medical Microbiology 1993-08-01

Use of tellurite for the selection of verocytotoxigenic Escherichia coli O157.

P M Zadik, P A Chapman, C A Siddons

Index: J. Med. Microbiol. 39 , 155-158, (1993)

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Abstract

Potassium tellurite was assessed for the selection of verocytotoxigenic (VT+) Escherichia coli O157. MICs were higher for VT+ E. coli O157 than for other strains of E. coli and for Aeromonas spp. MacConkey medium containing sorbitol, tellurite and cefixime (TC-SMAC) permitted the growth of VT+ E. coli O157 and Shigella sonnei but partially or completely inhibited the growth of 67% of other strains of E. coli and all or most strains of other sorbitol-non-fermenting species tested. Of 391 rectal swabs from cattle screened on TC-SMAC medium, 26 yielded isolates of VT+ E. coli O157 whereas sorbitol-MacConkey medium with cefixime and rhamnose yielded only nine isolates. Inclusion of potassium tellurite in sorbitol-MacConkey agar markedly increased the rate of isolation of VT+ E. coli O157 from cattle rectal swabs and may do so for other types of specimen.