Combined usage of serodiagnosis and O antigen typing to isolate Shiga toxin-producing Escherichia coli O76:H7 from a hemolytic uremic syndrome case and genomic insights from the isolate

Abstract

Hemolytic uremic syndrome (HUS) is a life-threatening disease caused by Shiga toxin-producing Escherichia coli (STEC) infection. The treatment approaches for STEC-mediated typical HUS and atypical HUS differ, underscoring the importance of rapid and accurate diagnosis. However, specific detection methods for STECs other than major serogroups, such as O157, O26, and O111, are limited. This study focuses on the utility of PCR-based O-serotyping, serum agglutination tests utilizing antibodies against the identified Og type, and isolation techniques employing antibody-conjugated immunomagnetic beads for STEC isolation. By employing these methods, we successfully isolated a STEC strain of a minor serotype, O76:H7, from a HUS patient.

Keywords: Shiga toxin-producing Escherichia coli; genome analysis; hemolytic uremic syndrome; immunomagnetic separation; immunoserology.

Fig 1

Procedures for diagnosis and isolation of causative STEC from an HUS patient.

Fig 2

Phylogenetical relationships of Shiga toxin-producing Escherichia coli O76 in Japan and other E. coli strains. Boxes on the right represent the information on symptom of the patients and stx profile of the E. coli O76 isolates as shown in the legends. Detailed information of E. coli O76 isolates is shown in Table 1. STEC O76:H7 isolate from the 2013 HUS case was highlighted in orange. Serotype and pathotype information of non-O76 E. coli strains is shown in the parentheses and Table S1. The tree was rooted by E. fergusonii ATCC35469 (NCBI accession no. CU928158). Scale bar represents substitution rate per site.

Fig 3

Phylogenetic relationships of Shiga toxin-producing Escherichia coli O76:H7 (A) and O76:H19 (B) in Japan. Boxes on the right represent the information on symptom of the patients and stx profile of the E. coli O76 isolates as shown in the legends. Detailed information of E. coli O76 isolates is shown in Table 1. STEC O76:H7 isolate from the 2013 HUS case was highlighted in orange. Scale bar represents substitution rate per site.

Fig 4

Comparison of Stx2a phages and Stx2a phage-harboring phages of O76:H7 JNE132847 and O145:H28 112648 showed difference in gene component. CDSs are shown as arrows. Similarity between the sequences was calculated by BLASTN program. Integration site of Stx2a phage of JNE132847 in the λ-like phage was indicated. This figure was generated by using GenomeMatcher v.3.06 and clinker v.0.0.25.

Fig 5

Comparison of early region of Stx2a phage of Shiga toxin-producing Escherichia coli O76:H7 showed the diversity of the phage. CDSs are shown as arrows. Similarity between the sequences was calculated by BLASTN program. This figure was generated by using GenomeMatcher v.3.06 and clinker v.0.0.25.