Diarrhea is one of the most common problems clinicians encounter, yet diagnosing and managing it remains far from straightforward. A state-of-the-art review in Clinical Infectious Diseases highlights how newer diagnostic tools and therapies have expanded options for care, while also creating new pitfalls, particularly when symptoms persist or recur.
In the review, corresponding author Andi L. Shane, MD, of the Division of Pediatric Infectious Disease at Emory University School of Medicine, Atlanta, and colleagues emphasize that diarrhea is not a single clinical entity. Management depends on whether symptoms are acute, persistent, or chronic, and whether infection is truly the cause. For acute diarrhea, which is often viral or toxin-mediated, supportive care remains the cornerstone. Oral rehydration therapy, electrolyte replacement, and early nutritional support are the most effective interventions for preventing complications such as dehydration and acute kidney injury.
The authors state that diagnostic testing in acute illness should be selective. The review discusses the widespread use of multiplex gastrointestinal PCR panels, such as syndromic tests that simultaneously detect organisms including Salmonella, Shigella, Campylobacter, Norovirus, Rotavirus, and Giardia. These tests can deliver results within hours, but the authors caution that they often detect organisms that represent colonization or residual nucleic acid rather than active infection. For example, detection of Clostridioides difficile or enteropathogenic E. coli in a patient with mild, self-limited diarrhea may not explain symptoms and should not automatically prompt treatment.
The authors recommend antibiotics only in specific scenarios, such as severe bacterial diarrhea, dysentery, cholera, or infection in high-risk patients. When empiric therapy is needed, clinicians may need to choose treatment without susceptibility data, increasing the importance of local resistance patterns. In many cases, the authors state, antibiotics offer no benefit and expose patients to adverse effects and antimicrobial resistance.
The approach changes when diarrhea becomes persistent or chronic. The review emphasizes that ongoing symptoms may reflect postinfectious inflammation, altered gut motility, bile acid malabsorption, or microbiome disruption rather than continued infection. Repeated stool PCR testing in these patients is often low yield. Instead, management may involve symptom-directed therapies such as antimotility agents, bile acid binders, dietary modification, or referral for endoscopic evaluation.
The review devotes significant attention to Clostridioides difficile infection, which illustrates the overlap between acute and recurrent disease. For initial episodes, current guidelines favor fidaxomicin over vancomycin in adults due to lower recurrence rates. For patients with recurrent infection, microbiome-based strategies play an increasing role. These include fecal microbiota transplantation (FMT) and newer live biotherapeutic products, which aim to restore colonization resistance and reduce recurrence risk. However, the authors note that the role of probiotics and microbiome therapies outside recurrent C. difficile infection remains uncertain.
Across all forms of diarrhea, the authors emphasize the importance of shared decision-making and reassessing goals of care. Some patients recover quickly with minimal intervention, while others develop chronic symptoms that require multidisciplinary management and repeated evaluation. Clinicians are encouraged to reconsider whether ongoing symptoms represent infection or a postinfectious or noninfectious condition.
Looking ahead, the review calls for better diagnostics, such as biomarkers that distinguish true infection from colonization, and improved access to effective therapies for all eligible people.
Disclosures can be found in the published review.
Source: Clinical Infectious Diseases
