Histologic and Clinical Correlates of Multiplex Stool Polymerase Chain Reaction Assay Results

Multiplex stool polymerase chain reaction tests (SPTs) simultaneously test for many enteric pathogens. However, the clinical significance of a positive result, particularly in the context of chronic gastrointestinal disease, remains controversial.

To determine whether SPT results correlate with findings on colon biopsies obtained within a week of SPT or with clinical features.

We reviewed 261 colon biopsies during a 15-month period that were obtained within a week of SPT, along with available clinical information, from patients with and without chronic idiopathic inflammatory bowel disease (CIIBD). Statistical analysis was used to test associations between SPT result, histologic features, and clinical variables.

The most commonly detected pathogens were Clostridium difficile, enteropathogenic Escherichia coli, and norovirus. The presence of underlying CIIBD did not correlate with a positive SPT result or with a specific pathogen. Positive SPT result was significantly associated with neutrophilic activity, pseudomembranes, and increased intraepithelial lymphocytes. In addition, the presence of C difficile on SPT was significantly associated with pseudomembranes and neutrophilic activity. There were no other statistically significant relationships between SPT result and any other histologic abnormality. Only about half of SPT positive results were acted on clinically, and most patients with CIIBD were managed as having a presumed IBD flare.

SPTs have many advantages; however, interpretation of results, particularly in the background of chronic gastrointestinal disease, remains a challenge. Therapeutic decisions influenced by a positive SPT result should integrate biopsy findings, clinical data, and other laboratory testing to avoid inappropriate treatment.