Abstract
Fast and reliable isolation of Shiga toxin-producing Escherichia coli (STEC) remains a challenge in routine diagnostics. The present study evaluated the performance of the CHROMagar™ STEC medium by testing the growth capacity of 39 STEC strains from human patients and of 35 non-target strains. The majority (83.3 %) of the 18 STEC strains belonging to the top-five serogroups (O26, O103, O111, O145, O157) did grow on and showed typical mauve colonies (exceptions were one O26 isolate and two sorbitol-fermenting non-motile O157 isolates). However, only five of the 21 STEC strains not belonging to the top-five serogroups showed growth and typical colonies. Of the 28 stx-negative E. coli strains (including 13 O157 isolates) and the seven nonE. coli strains, 10 stx-negative/eae-positive E. coli strains of serogroups O2, O26, O113, O128, O145 and O177 did grow and showed typical colonies. Thus, the CHROMagar™ STEC medium can not be recommended as a primary STEC screening method in routine diagnostics. The CHROMagar™ STEC medium should therefore only be used for specific questions or in routine STEC diagnostics in combination with another method or medium
Cernela, Nicole