Tests for Shiga toxin producing E. coli (STEC) infections
Laboratory methods to detect STEC21:
- Enzyme Immunoassay (EIA)
- A rapid test for the detection of Shiga toxins 1 and 2
- Stool culture
- Does not detect non-O157 Shiga toxin producing E. coli
- Assays for STx genes using probes or PCR
- Expensive procedures usually performed at the state laboratory level
Who should be tested?
STEC infection is as common as Salmonella or Campylobacter infections but potentially more serious than either.17 Testing should not be ruled out due to17:
- Patient age
- The absence of blood in diarrhea
- The season of the year
- The absence of leukocytes in stool
CDC test protocol
Rapid turnaround allows physicians to quickly assess the possibility of progression to severe disease. The CDC recommends a two-test strategy17:
The Meridian Bioscience tests for Shiga toxin and O157:H7 E. coli
Meridian offers two tests for the presence of Shiga toxin and one for O157:H7 antigens:
In an evaluation using conventional SMAC culture as a reference standard, the Premier™ EHEC detected 40% more STEC than the SMAC culture.22 The authors determined that the Premier™ EHEC would allow more accurate identification of O157:H7 disease and non-O157:H7 Shiga toxin producing disease.
The CDC notes that Shiga toxin (STx) testing of stool samples from an outbreak of foodborne disease in a New York state prison facilitated the detection of non-O157 STEC. The CDC recommends that toxin testing be confirmed by culture.23
The Meridian ImmunoCard STAT!® E. coli O157 Plus is the only rapid antigen test to identify Shiga toxin producing O157 strains.
Testing for Campylobacter infection
Meridian offers two tests for Campylobacter antigens: ImmunoCard STAT!® CAMPY
Campylobacter infection receives far less attention than E. coli, perhaps because it lacks the potential lethality of Shiga toxins. Routine detection of isolates is complicated by the slow growth rate of Campylobacter species and their relatively short life in stool samples. Gram stains have a sensitivity of only 50%-75%.12
Treating STEC and Campylobacter infections
