Detection of Gastrointestinal Pathogens from Stool Samples on Hemoccult Cards by Multiplex PCR

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Travelers' diarrhea (TD) impacts up to 30% of international travelers, with a significant knowledge gap regarding its specific causes.
• Current diagnostic methods for TD pathogens are hindered by limited laboratory infrastructure at travel destinations and difficulties in transporting conventional stool samples.
• There is a need for a convenient and reliable stool sampling method suitable for remote conditions.

Purpose of the Study:

• To evaluate the efficacy of Hemoccult cards as a stool sampling method for detecting travelers' diarrhea (TD) pathogens.
• To assess the compatibility of Hemoccult card-based samples with multiplex PCR for identifying viral, bacterial, and protozoal TD agents.
• To determine the reliability of Hemoccult cards for preserving pathogen viability during extended storage periods simulating travel.

Main Methods:

• Hemoccult cards were used for stool sampling and compared against conventional stool samples using serial dilutions to determine last positive dilution steps (LPDs) and last positive sample concentrations (LPCs).
• Model pathogens including *C. jejuni*, *E. histolytica*, norovirus GI, and GII were tested.
• Card-based samples were stored for up to 6 weeks to simulate travel duration, with pathogen detection assessed at weekly intervals.

Main Results:

• Comparable LPDs/LPCs were observed between conventional stool samples and Hemoccult card samples, indicating similar detection limits.
• High recovery rates were achieved after storage on Hemoccult cards: 97.6% for *C. jejuni*, 100% for *E. histolytica*, 97.6% for norovirus GI, and 100% for GII.
• Pathogen detection was successful up to 42 days (6 weeks) after sample collection on cards.

Conclusions:

• Hemoccult cards provide a reliable method for stool sampling in the context of travelers' diarrhea (TD).
• Combining Hemoccult cards with multiplex PCR enables effective detection of key TD pathogens.
• This approach facilitates convenient sample storage and transport, overcoming limitations of conventional methods for diagnosing TD in travelers.