The present disclosure describes compositions, methods and kits for detection of one or multiple microorganism contaminants in samples. Some embodiments relate to detecting one or more microorganisms producing virulence factors such as shiga toxin stx1 and stx2 and eae. Some embodiments relate to detection of STEC microorganisms including an E. coli O26, an E. coli O45, an E. coli O103, an E. coli O111, an E. coli O121 or an E. coli O145. In some embodiments, compositions, methods and kits can detect and identify individual serotypes of shiga toxin producing microorganisms. Workflows for multiple microbe detection and identification are also described.