Clinical and Microbiological Evaluation of EPEC and EAEC Detected by Multiplex Gastrointestinal PCR

Enteropathogenic Escherichia coli (EPEC) and enteroaggregative Escherichia coli (EAEC) are frequently detected diarrheagenic E. coli pathotypes in multiplex gastrointestinal panels, but their clinical interpretation remains challenging, particularly in asymptomatic cases or with co-detected pathogens. This study determined the frequency of EPEC and EAEC in stool samples tested by multiplex gastrointestinal PCR and evaluated their relationship with recorded clinical presentations.

This retrospective observational study included stool samples submitted to the microbiology laboratory of a tertiary care hospital between January 2024 and October 2025. Samples were analyzed using two commercial multiplex real-time PCR panels applied consecutively: the Bio-Speedy® Gastroenteritis RT-qPCR MX-24T Panel and the QIAstat-Dx® Gastrointestinal Panel 2. Demographic data, requesting units, EPEC/EAEC results, co-detected pathogens, and clinical indications were retrieved from the hospital information system.

Among 2958 stool samples, 53.9% were from male patients and 65.7% from pediatric patients. Irrespective of other co-detected pathogens, 360 samples (12.2%) were EPEC-only group, 356 (12.0%) were EAEC-only group, and 240 (8.1%) showed EPEC+EAEC co-detection. Diarrhea was the most common complaint in all groups. Bloody stool was more frequent in the EPEC-only group (10.3%; p=0.020), whereas asymptomatic screening or follow-up testing was more common in the EAEC-only group (9.8%; p<0.001). Co-detection with ETEC and EIEC was particularly prominent in samples positive for both EPEC and EAEC.

Isolated EPEC positivity appeared more closely associated with symptomatic presentations. EAEC-only detection showed a higher proportion of asymptomatic screening/follow-up indications than the other detection groups, but this represented a minority of EAEC-positive cases. These findings support cautious interpretation of EAEC detection, particularly in the presence of co-detected pathogens. Multiple-pathogen results should be interpreted with the clinical context.