title: Clinical isolates of Shiga toxin 1a-producing Shigella flexneri with an epidemiological link to recent travel to Hispañiola.
abstract: Shiga toxins (Stx) are cytotoxins involved in severe human intestinal disease. These toxins are commonly found in Shigella dysenteriae serotype 1 and Shiga-toxin-producing Escherichia coli; however, the toxin genes have been found in other Shigella species. We identified 26 Shigella flexneri serotype 2 strains isolated by public health laboratories in the United States during 2001-2013, which encode the Shiga toxin 1a gene (stx1a). These strains produced and released Stx1a as measured by cytotoxicity and neutralization assays using anti-Stx/Stx1a antiserum. The release of Stx1a into culture supernatants increased ≈100-fold after treatment with mitomycin C, suggesting that stx1a is carried by a bacteriophage. Infectious phage were found in culture supernatants and increased ≈1,000-fold with mitomycin C. Whole-genome sequencing of several isolates and PCR analyses of all strains confirmed that stx1a was carried by a lambdoid bacteriophage. Furthermore, all patients who reported foreign travel had recently been to Hispañiola, suggesting that emergence of these novel strains is associated with that region.
authors.forename: Miranda D
authors.initials: MD
authors.lastname: Gray
authors.forename: Keith A
authors.initials: KA
authors.lastname: Lampel
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Strockbine
authors.forename: Reinaldo E
authors.initials: RE
authors.lastname: Fernandez
authors.forename: Angela R
authors.initials: AR
authors.lastname: Melton-Celsa
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Maurelli
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D004293:Dominican Republic / Q000453:epidemiology; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology*; D006205:Haiti / Q000453:epidemiology; D006801:Humans; D008242:Lysogeny; D016685:Mitomycin / Q000494:pharmacology; D009154:Mutation; D039002:Prophages; D065288:Serogroup; D022622:Shiga Toxin 1 / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012763:Shigella flexneri / Q000145:classification / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D017906:Siphoviridae / Q000235:genetics / Q000502:physiology; D014709:Vero Cells; D014774:Virulence
chemical_list: D022622:Shiga Toxin 1; D016685:Mitomycin