APIM243887243 - CME/CMLE - GI Pathogen – Testing Algorithm-APIM243887243

APIM243887243 - Educational Activity

Pdf Summary

This educational commentary by Jessica Brashear, DCLS, MLS(ASCP)CM, provides a detailed overview of gastrointestinal (GI) infections, their pathogens, and testing algorithms, emphasizing their clinical and public health significance. GI infections, caused by bacterial, viral, and parasitic agents, affect millions annually in the U.S., leading to significant healthcare utilization and mortality.<br /><br />Key bacterial pathogens include Campylobacter (the most common worldwide), Salmonella (causing gastroenteritis and enteric fevers), Shigella (with emerging extensively drug-resistant [XDR] strains posing public health challenges), and various diarrheagenic Escherichia coli strains responsible for pediatric diarrhea and diverse clinical syndromes. Clostridioides difficile is notable for antibiotic-associated diarrhea and healthcare-associated colitis, with increasing community cases and antibiotic resistance.<br /><br />Viral pathogens primarily include rotavirus and norovirus, both causing acute viral gastroenteritis with symptoms like diarrhea, vomiting, and dehydration. Rotavirus incidence has decreased in vaccinated populations, but norovirus remains the leading cause of acute GI illness in the U.S., often causing outbreaks in institutional settings.<br /><br />Parasitic infections mainly involve protozoa like Cryptosporidium and Giardia intestinalis, which spread via contaminated water and person-to-person contact, particularly affecting children and low-resource areas.<br /><br />Diagnostic testing has evolved from traditional culture, microscopy, and immunoassays toward molecular methods like multiplex polymerase chain reaction (mPCR), which enhance speed, sensitivity, and breadth of pathogen detection, including bacteria, viruses, and parasites. However, molecular tests do not yield isolates for antibiotic susceptibility testing and may detect nonviable organisms, necessitating clinical context for interpretation.<br /><br />Testing algorithms depend on patient context such as hospitalization status, symptom duration, immune status, and travel history, guiding the choice of diagnostic methods to optimize clinical management and public health responses. Ultimately, integrating advanced molecular diagnostics with clinical judgment improves outcomes, outbreak control, and antimicrobial stewardship in GI infections.

Keywords

gastrointestinal infections

bacterial pathogens

viral gastroenteritis

parasitic infections

diagnostic testing

molecular methods

multiplex PCR

antimicrobial resistance

public health

clinical management