Molecular Identification of Gastroenteritis Pathogens among Adults and Children in Al‑Ahsa, Saudi Arabia: A Retrospective Study

Background: Infectious gastroenteritis is one of the most prevalent diseases worldwide. Multiplex molecular assays enable simultaneous and rapid detection of various gastrointestinal pathogens, but it has not been used to report the prevalence of such infections from Saudi Arabia. Objectives: To determine the viral, bacterial, and parasitic pathogens implicated in infectious diarrhea among children and adults and describe their seasonality in Al-Ahsa, Saudi Arabia. Materials and Methods: This is a retrospective study that included all documented results of syndromic PCR-based gastrointestinal pathogen panels between November 1, 2021, and March 31, 2023, from a private, tertiary healthcare hospital in Al-Ahsa, Saudi Arabia. Patients’ demographics, detected pathogens, recorded temperature, and date of testing were retrieved from the hospital’s electronic medical records. Results: A total of 606 non-duplicate samples were included. Viral, bacterial, and parasitic pathogens were detected in 24.8%, 50.5%, and 3.8% of samples, respectively. Of the total tested samples, norovirus (13.2%), and sapovirus (4.5%) were the two most commonly detected viruses. Enteropathogenic E. coli (21.6%) and enteroaggregative E. coli (9.7%) were the most commonly identified bacterial targets. The only parasitic pathogen detected was Crytposporidium spp. (3.8%). Children aged ≤5 years tested positive for most pathogens, while elderly patients were mainly positive for diarrheagenic E. coli, C. difficile, norovirus, and sapovirus. Most pathogens peaked during summer, while norovirus, Campylobacter spp., and Cryptosporidium spp. were predominantly seen in winter or spring. Bacterial pathogens were commonly co-detected with gastroenteritis viruses. Conclusion: We describe variable distributions of viral, bacterial, and parasitic causes of diarrhea across age groups and seasons in Saudi Arabia. Viral and bacterial pathogens (specifically, norovirus and diarrheagenic E. coli) are the predominant pathogens in infectious gastroenteritis.