Understanding the role of molecular testing in modern healthcare

Acute gastroenteritis is a considerable health concern

Acute gastroenteritis continues to put significant pressure on public health services worldwide. Patients typically present with self-limiting symptoms with a sudden onset and short duration, ranging from diarrhea, vomiting and nausea to abdominal discomfort or cramps. However, the condition can escalate beyond mild illness in vulnerable patients. In 2021, diarrheal disease was associated with more than one million deaths globally, remaining a leading cause of mortality in children under five years old [1]. Campylobacteriosis and salmonellosis were the most frequently reported food-borne gastrointestinal infections in the European Union in 2023, followed by Shiga toxin-producing Escherichia coli (STEC) and Yersinia enterocolitica [2]. Shiga toxins can trigger hemolytic uremic syndrome (HUS), characterized by hemolysis, thrombo-cytopenia and acute kidney injury, with limited treatment options as antibiotic therapy is not recommended [3]. Early detection of HUS-associated toxins Shiga toxin 2 (Stx2a) and Shiga toxin 1 (Stx1a) is therefore critical to guide appropriate intervention and ensure referral of positive samples to health laboratories for isolate recovery and confirmation.

There are a number of other enteric bacteria that are often detected in gastroenteritis, but their pathogenic potential and relevance to patient management are less well defined. Aeromonas species frequently colonize healthy individuals and lack strong evidence of pathogenicity, while detection of Clostridioides difficile does not reliably indicate active infection. Current guidance therefore recommends selective testing for patients with clinically significant diarrhea and relevant risk factors using a multistep algorithm to confirm toxin production [4].

Campylobacter (Adobe Stock)
Campylobacter is one of the most common causes of bacterial food-borne disease in humans.

Accurate diagnosis is essential but can be time-consuming

Given the overlap in clinical presentation across a wide range of pathogens, rapid and accurate diagnosis is essential for effective management of acute gastroenteritis. Despite this, many traditional culture-based methods are labour-intensive and often take several days to identify causative pathogens [5].

E. coli bacterial colonies on MacConkey agar (Adobe Stock)
Traditional culture-based methods of pathogen identification can be slow and labour-intensive.

Molecular diagnostics delivers faster results

Molecular diagnostics, particularly multiplex PCR panels, deliver faster and more sensitive detection with results available within hours, supporting earlier decision-making, improved infection control and better patient outcomes [5]. Healtheconomic evidence further demonstrates that, despite higher upfront costs, molecular testing can reduce downstream investigations and hospital stays, while culture remains essential for confirmatory testing and public health surveillance [5]. Molecular panels deliver faster and more sensitive detection than traditional culture, serving as a complementary tool to work alongside antimicrobial susceptibility testing and public health surveillance. Hologic has developed the Panther Fusion® GI Bacterial and Expanded Bacterial assays, which – together with Hologic’s fully automated Panther® System – enable rapid and reliable detection of the most clinically-relevant bacterial pathogens directly from stool samples.

The GI Bacterial Assay detects common causes of bacterial gastroenteritis, including Salmonella, Campylobacter, Shigella and Shiga toxin-producing E. coli, while the Expanded Bacterial Assay extends coverage to Yersinia enterocolitica, Vibrio species, E. coli O157 and Plesiomonas shigelloides. Together, these assays support high throughput, random access testing with minimal hands-on time, allowing laboratories to expand molecular diagnostics without added workflow complexity.

Hologic BV
1930 Zaventem
Belgium

To find out more about Hologic’s range of gastrointestinal solutions, visit: www.hologic.co.uk/products/gastrointestinal-solution

 Bibliography
1. Kyu HH, Vongpradith A, Dominguez RMV et al. Global, regional, and national age-sex-specific burden of diarrhoeal diseases, their risk factors, and aetiologies, 1990–2021, for 204 countries and territories: a systematic analysis for the Global Burden of Disease Study 2021. Lancet Infect Dis. 2025;25(5):519–536 (https://shorturl.at/d2NoG).
2. The European Union One Health 2023 Zoonoses Report. EFSA Journal. 2024;22(12): e9106 (https://doi.org/10.2903/j.efsa.2024.9106).
3. Kakoullis L, Papachristodoulou E, Chra P, Panos G. Shiga toxin-induced haemolytic uraemic syndrome and the role  of antibiotics: a global overview. J Infect. 2019;79(2):75–94 (https://doi.org/10.1016/j.jinf.2019.05.018).
4. Polage CR, Gyorke CE, Kennedy MA et al. Overdiagnosis of Clostridioides difficile infection in the molecular test era. JAMA Intern Med. 2015; 175(11):1792–1801 (https://doi.org/10.1001/jamainternmed.2015.4114).
5. Beal SG, Tremblay EE, Toffel S et al. A gastrointestinal PCR panel improves clinical management and lowers health care costs. J Clin Microbiol. 2018;56(1):e01457-17 (https://doi.org/10.1128/jcm.01457-17).