{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T13:10:23Z","timestamp":1788959423496,"version":"build-2803163510"},"reference-count":28,"publisher":"American Society for Microbiology","issue":"9","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["J Clin Microbiol"],"published-print":{"date-parts":[[2026,9,9]]},"abstract":"ABSTRACT<\/jats:title>\n \n \n \n Infections caused by Shiga toxin-producing\n Escherichia coli<\/jats:italic>\n (STEC) strains carrying Shiga toxin 2 (\n stx<\/jats:italic>\n 2) are more likely to result in severe complications; however, most nucleic acid amplification tests used for STEC diagnosis do not differentiate between\n stx<\/jats:italic>\n 1 and\n stx<\/jats:italic>\n 2. We therefore sought to optimize\n stx<\/jats:italic>\n typing and isolate recovery methods to guide clinical and public health management.\n stx<\/jats:italic>\n polymerase chain reaction (PCR)-positive feces were cultured using CHROMagar STEC and gram-negative broth, with Stx1 and\/or Stx2 antigen detection by enzyme immunoassay (EIA) on colony growth or turbid broth. When cultures were EIA-negative, growth from MacConkey agar (MAC), Trypticase soy broth, and the gram-negative broth was then tested using a lab-developed typing PCR for\n stx<\/jats:italic>\n 1 and\n stx<\/jats:italic>\n 2. Colonies were isolated on CHROMagar STEC or MAC and identified using the typing PCR. Using both EIA and typing PCR, the\n stx<\/jats:italic>\n types were identified in 96.0% of cases (381\/397). In 65.2% (259\/397) of cases, culture was EIA-positive, of which 34.0% (87\/256) were Stx2-positive. Among cultures that were EIA-negative but typing PCR-positive, 64.8% (79\/122) were\n stx<\/jats:italic>\n 2-positive (\n P<\/jats:italic>\n < 0.0001 compared to EIA-positive). Using both EIA and typing PCR resulted in 72.6% (286\/394) of cases with successful attempts at isolate recovery, compared to 60.7% (239\/394) with EIA alone.\n E. coli<\/jats:italic>\n O157 was recovered from more EIA-positive cases (19.3%, 46\/239) than EIA-negative ones (4.3%, 2\/47) (\n P<\/jats:italic>\n = 0.0097). Typing PCR on cultures improves\n stx<\/jats:italic>\n typing (particularly\n stx<\/jats:italic>\n 2) and isolate detection compared to EIA alone. Screening BD Max PCR and subsequent typing PCR results showed excellent concordance.\n <\/jats:p>\n <\/jats:sec>\n \n IMPORTANCE<\/jats:title>\n \n Escherichia coli<\/jats:italic>\n strains with one or both types of Shiga toxins (\n stx1<\/jats:italic>\n and\n stx2<\/jats:italic>\n ) are a common cause of bacterial diarrhea and can lead to serious complications such as kidney failure, especially in children. Infection by\n stx2<\/jats:italic>\n -positive strains is more likely to do so. Therefore, knowing whether the infection is caused by a strain carrying\n stx2<\/jats:italic>\n is important for risk assessment and case follow-up. The conventional way to diagnose these infections is to grow the bacteria from stool, but most laboratories currently use nucleic acid detection (e.g., bacterial DNA detection by polymerase chain reaction [PCR]), and these assays do not differentiate between the two toxin genes. Culture is therefore required to determine toxin type, as well as for public health outbreak investigations, which require an isolate for whole-genome sequencing for serotyping and cluster analysis. We identified culture media and a PCR-based method to detect\n stx2<\/jats:italic>\n in culture that improved the detection of\n stx2<\/jats:italic>\n and isolate recovery. Our findings provide more accurate results for clinicians to improve patient care and tools for public health teams to control and prevent outbreaks.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1128\/jcm.00429-26","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T14:03:01Z","timestamp":1786716181000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Improving isolate recovery and identification of the Shiga toxin type in Shiga toxin nucleic acid test-positive feces"],"prefix":"10.1128","volume":"64","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9062-6346","authenticated-orcid":true,"given":"Byron M.","family":"Berenger","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rjd747","id-type":"ROR","asserted-by":"publisher"}],"name":"Microbiology, Alberta Precision Laboratories","place":["Calgary, Canada"]},{"id":[{"id":"https:\/\/ror.org\/004rjd747","id-type":"ROR","asserted-by":"publisher"}],"name":"Provincial Laboratory for Public Health, Alberta Precision Laboratories","place":["Calgary, Canada"]},{"id":[{"id":"https:\/\/ror.org\/03yjb2x39","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary","place":["Calgary, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas","family":"Griener","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rjd747","id-type":"ROR","asserted-by":"publisher"}],"name":"Microbiology, Alberta Precision Laboratories","place":["Calgary, Canada"]},{"id":[{"id":"https:\/\/ror.org\/03yjb2x39","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary","place":["Calgary, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0851-9803","authenticated-orcid":true,"given":"Linda","family":"Chui","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/004rjd747","id-type":"ROR","asserted-by":"publisher"}],"name":"Provincial Laboratory for Public Health, Alberta Precision Laboratories","place":["Calgary, Canada"]},{"id":[{"id":"https:\/\/ror.org\/0160cpw27","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Laboratory Medicine and Pathology, University of Alberta","place":["Edmonton, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_4_2_2","doi-asserted-by":"publisher","DOI":"10.15585\/mmwr.mm7326a1"},{"key":"e_1_3_4_3_2","doi-asserted-by":"crossref","unstructured":"European Food Safety Authority (EFSA) European Centre for Disease Prevention and Control (ECDC). 2023. 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