Clinical Impact of Stool Polymerase Chain Reaction (PCR) Testing in Hospitalized Patients with Acute Diarrhea: A Retrospective Observational Study

<b>Background/Objectives</b>: Acute diarrheal illnesses are a major cause of hospital admissions, particularly in immunocompromised patients. Traditional diagnostic methods are slow and often insensitive, delaying treatment. In contrast, PCR panels provide rapid, sensitive detection of multiple pathogens. This study evaluates stool PCR testing in hospitalized adults and its impact on clinical decisions and antimicrobial stewardship. <b>Methods</b>: We conducted a retrospective study at Bistrița County Hospital, Romania (September 2023-September 2024), including 75 adults with acute diarrhea and negative conventional stool tests. PCR testing (VIASURE panels I and II) detected 11 bacteria, 6 viruses, and 5 parasites. Clinical and therapeutic data were analyzed, and logistic regression identified predictors of PCR positivity and adverse outcomes. <b>Results</b>: PCR was positive in 78% of cases, with <i>Campylobacter</i> spp. (57.6%) and <i>Clostridioides difficile</i> (20.3%) being the most common. Bloody diarrhea independently predicted PCR positivity (OR 9.78, <i>p</i> = 0.047). Immunosuppression and end-stage liver disease were linked to worse outcomes. PCR results led to antimicrobial therapy adjustments in 40 patients (<i>p</i> = 0.001), correcting inappropriate antibiotic use in 66% of those receiving empirical treatment. Targeted therapy significantly reduced antimicrobial duration from 7 to 5 days (<i>p</i> = 0.00001). <b>Conclusions</b>: Stool PCR testing enhances pathogen detection, guides targeted therapy, and reduces inappropriate antibiotic use, supporting antimicrobial stewardship and improving outcomes in selected hospitalized patients.