Shiga Toxin 2a in Escherichia albertii

Abstract

Escherichia albertii is an emerging human enteric pathogen (1). It belongs to the attaching and effacing group of bacteria, which also includes enteropathogenic and Shiga toxin-producing Escherichia coli (EPEC and STEC, respectively). Shiga toxin-producing E. albertii has been described, however, only in association with Shiga toxin (stx) subtype 2f (2). Sporadic infections as well as foodborne outbreaks caused by E. albertii have been reported, although rarely (3, 4). The prevalence, epidemiology, and clinical relevance of E. albertii are poorly understood, probably due to underestimation and misclassification of this pathogen (4). The phenotypic features distinguishing E. albertii from E. coli include a negative indole reaction and an inability to ferment lactose-, Dsorbitol, and D-xylose (1).In Norway, all presumptive enteropathogenic E. coli strains isolated from humans are submitted to the National Reference Laboratory for Enteropathogenic Bacteria for biochemical verification and for classification into well-known pathotypes according to virulence genes present (L. T. Brandal, A. L. Wester, H. Lange, I. Løbersli, B. A. Lindstedt, L. Vold, and G. Kapperud, submitted for publication). For outbreak detection purposes, all E. coli isolates are investigated with a generic multilocus variable-number tandem-repeat analysis (MLVA) (5).By these routine analyses, a nonmotile, ␤-D-glucuronidase-, lactose-, and xylose-negative isolate with eae and stx 2 was identified. This isolate had an MLVA profile often seen in E. albertii (NA-NA-NA-NA-NA-NA-5-X-X-NA, where NA designates a locus not present and X indicates different repeat numbers). A PCR specific for E. albertii was conducted (6), and 16S rRNA sequencing was performed (MicroSEC 500 16S rRNA gene bacterial sequencing kit; Life Technologies), both of which confirmed the isolate as E. albertii. stx 2 was subtyped and sequenced (7), and the expression of the stx 2a gene was verified (ImmunoCard STAT!EHEC; Meridian Bioscience Europe). All E. albertii isolates identified from 2008 to 2014 (n ϭ 39) were examined for the presence of stx 2f (8) and the cytolethal distending toxin B gene (cdtB) (9).Interestingly, the E. albertii isolate identified in the present study carried stx 2a , hitherto never reported in E. albertii. Additionally, we showed that stx 2a was expressed. This indicates that E. albertii is able to transduce not only stx 2f -carrying bacteriophages but also stx 2a -carrying bacteriophages. STEC harboring eae and stx 2a are considered highly virulent and have the ability to induce life-threatening hemolytic uremic syndrome (HUS) in infected patients (10). In contrast, STEC harboring stx 2f are associated with milder symptoms (11) and have, to our knowledge, never previously been detected in HUS patients. The patient infected with stx 2a -positive E. albertii was 48 years old, had bloody diarrhea, and was infected in Norway (Table 1). Domestically acquired E. albertii infection was commonly seen in patients included in the present study; however, the majori...

Implications of stx loss for clinical diagnostics of Shiga toxin-producing Escherichia coli

“…In our work, stx loss was also detected in a patient infected with stx2a-positive E. albertii. This isolate was obtained from a patient suffering from bloody diarrhea [27]. To our knowledge, this study is the first to illustrate that stx2 may be lost from E. albertii.…”

“…The 12 stx-positive isolates represented four different Oserogroups. One isolate was an unknown O-serogroup and one isolate was identified as Escherichia albertii [27] ( Table 1). CHROMagar STEC was successful in selecting for STEC O157 and suppressed growth of commensal E. coli.…”

Isolation and Characterization of an <i>Escherichia albertii</i> Strain Producing Three Different Toxins from a Child with Diarrhea

“…Thus, several E. albertii strains have been misidentified as EPEC (18,21). In contrast to EPEC, a proportion of E. albertii strains harbor various toxin genes, including cdt (orthologs of E. coli cdt-I and cdt-II) and/ or stx2 (stx2a and stx2f) (18,22). Since there are only a limited number of reports on the isolation and identification of E. albertii (18)(19)(20)(21)(22)(23)(24), more epidemiological information is needed to understand its pathogenicity and properties.…”

Harnessing The Power Of Recombineering To Interrogate The Virulome Of Escherichia albertii

“…Besides the LEE, the genome of E. albertii also harbors other virulence determinants. For instance, a stx 2a -expressing E. albertii strain was recently isolated from a patient with bloody diarrhea [14] . Stx2a is a very potent toxin, which, besides the genus Shigella, has traditionally been associated with EHEC [14][15][16] .…”

“…For instance, a stx 2a -expressing E. albertii strain was recently isolated from a patient with bloody diarrhea [14] . Stx2a is a very potent toxin, which, besides the genus Shigella, has traditionally been associated with EHEC [14][15][16] . Bacteria that express stx 2a are characterized as highly virulent because they can induce the life-threatening pathology of hemolytic uremic syndrome (HUS) [17,18] .…”