Detection of Shiga-toxin Producing Escherichia coli in Pediatric Patients’ Stool Specimens with Multiplex Infectious Diarrhea Panel Nucleic-acid Amplification Testing
Eugene Y H Yeung, Roxanna S D MohammedAbstract
Background
Since 2022, diagnostic laboratories in British Columbia (BC), Canada, have been advised to replace traditional bacterial stool culture testing with multiplex infectious diarrhea panel nucleic-acid amplification testing (IDP-NAAT), which contains a minimum of 14 common pathogens, including Shiga-toxin producing Escherichia coli (STEC), which is known to cause hemolytic uremia syndrome with antimicrobial use, especially in pediatric patients. NAAT is generally more sensitive than culture testing. LifeLabs BC implemented the IDP-NAAT in September 2023 and subsequently conducted a retrospective audit to determine whether the number of STEC positive results increased since the implementation, signaling a pseudo-outbreak.
Methods
LifeLabs BC microbiology laboratories, connected with 129 collection centres in urban and rural communities in the province, provided the laboratory data on STEC results. An audit was conducted from September 2022 to August 2023, one year prior to implementation of IDP-NAAT in LifeLabs BC, and from October 2023 to September 2024, one year after the implementation of IDP-NAAT. Chi-square tests with Yates correction were used to compare differences before and after implementation of IDP-NAAT.
Results
Prior to implementation of IDP-NAAT, 15 of 5434 pediatric patient’s (age <18 years) stool specimens (0.276%) submitted for testing was positive for STEC. After the implementation of IDP-NAAT, 70 of 7506 of the pediatric patients’ stool specimens (0.933%; p < 0.05 vs. prior) submitted for testing was positive for STEC. In comparison, 22 of 3897 adult patients’ (age >18 years) stool specimens (0.056%) was positive for STEC prior to implementation of IDP-NAAT, compared to 522 of 55170 of adult patients’ stool specimens (0.946%; p < 0.05 vs. prior).
Conclusions
The positivity rate and number of STEC positive results among pediatric patients’ stool specimens were significantly higher after the implementation of IDP-NAAT. This increase could be suggestive of a pseudo-outbreak due to change in test methodology. More communications and educations may be warranted to remind clinicians that antimicrobial use in STEC infection does not improve symptoms but can cause hemolytic uremia syndrome, especially in pediatric patients. The increase in positivity rate among adults also suggested STEC infections may not be limited to pediatric populations.