Stx2d is a recently described Shiga toxin whose @entity137 is activated 10- to 1000-fold by the elastase present in @entity19 or @entity1 intestinal mucus. We examined Shiga toxigenic @entity526 (STEC) strains isolated from food and livestock sources for the presence of activatable stx(2d). The stx(2) operons of STEC were first analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis and categorized as stx(2), stx(2c vha), stx(2c vhb), or stx(2d EH250). Subsequently, the stx(2c vha) and stx(2c vhb) operons were screened for the absence of a PstI site in the stx(2A) subunit gene, a restriction site polymorphism which is a predictive indicator for the stx(2d) (activatable) genotype. Twelve STEC isolates carrying putative stx(2d) operons were identified, and @entity377 sequencing was used to confirm the identification of these operons as stx(2d). The complete @entity377 sequences of seven representative stx(2d) operons were determined. Shiga toxin expression in stx(2d) isolates was confirmed by immunoblotting. stx(2d) isolates were induced for the production of bacteriophages carrying stx. Two isolates were able to produce bacteriophages phi1662a and phi1720a carrying the stx(2d) operons. RFLP analysis of bacteriophage genomic DNA revealed that phi1662a and phi1720a were highly related to each other; however, the DNA sequences of these two stx(2d) operons were distinct. The STEC strains carrying these operons were isolated from retail ground beef. Surveillance for STEC strains expressing activatable @entity23345 d Shiga toxin among clinical cases may indicate the significance of this toxin subtype to @entity1 health.

Presence of activatable Shiga toxin genotype (stx(2d)) in Shiga toxigenic XXXX from livestock sources.

@entity1 :: ('9606', 'Species') :: ['human'] @entity23345 :: ('2054', 'Gene') :: ['Stx2'] @entity137 :: ('MESH:D064420', 'Disease') :: ['cytotoxicity'] @entity19 :: ('10090', 'Species') :: ['mouse'] @entity377 :: ('CHEBI:36976', 'Chemical') :: ['nucleotide'] @entity526 :: ('562', 'Species') :: ['Escherichia coli']
@entity526 :: (562,Species) :: ['Escherichia coli']
