Comparison of rida®quick verotoxino157 test, verocytotoxicty assay and pcr in detection of shiga toxins in cultures of human stool, animal faeces and meat products

Abstract EN

Shiga toxins (Stx) are the major virulence factors of STEC, which cause diarrhea, life-threatening haemolytic uraemic syndrome (HUS) and acute renal failure in children.

This work aimed to evaluate the new RIDA®QUICK Verotoxin/O157(RBiopharm, Darmstadt, Germany), which detects Stx & E.

coli serogroup O157 and to determine the extent of faecal contamination of meat products by STEC.

A total 623 samples, including 214 faecal samples collected from sheep, 209 stool samples from human and 200 samples of different meat products were cultured on Trypticase Soya Broth and CT-Sorbitol MacConkey agar, samples were Biochemically identified as Escherichia coli.

Further identifications were performed by serotyping and Vero cells cytotoxicity assay.

PCR for specific VT1/VT2 genes and RIDA®QUICK Verotoxin/O157 were applied on VCA positive samples.

The results of RIDA®QUICK revealed the detection of STEC in 14(93.33%), 6 (85.71%) and 13(86.66%) while PCR test detected 15(100%), 7(100%) and 15(100%) VCA positive samples from sheep, man and meat products, respectively.

Overall RIDA®QUICK Verotoxin / O157 Combi test detected 33(89.18%) from 37 strains of STEC that were positive for VCA and PCR.

The test was sensitive for the Stx1 (9/9 positive), Stx2 (18/22 positive) and Stx1& Stx2 (6/6).

Moreover, The sensitivity of the assay for the E.

coli O157 antigen was tested with 7 strains belonging to sheep (4 strains) and man (3strains), The RIDA Quick assay detected all of them.

Furthermore, Strains belonging to the non-O157 serogroups did not react for the O157 antigen in the RIDA Quick assay indicating a specificity of 100%.

In Conclusion: Fecal contamination of meat products is important route through which STEC pathogens enter the food chain and the new RIDA®QUICK Verotoxin/O157 is a highly sensitive, specific and rapid method to determine the presence of Stx and serogroup O157 in enrichment cultures.