April 18, 2007
Dipsticks for the rapid diagnosis of diarrhoeal diseases
Researchers from the Institut Pasteur in Paris, including one associate team at Inserm, have recently developed a diagnostic test able to be used at a patient's bedside for the major forms of bacillary dysentery (or shigellosis), a disease responsible for a million deaths every year across the world. Their study, conducted in collaboration with the Institut Pasteur of Ho Chi Minh City, Vietnam, is published in 'PLoS ONE'. Pasteur teams have already developed rapid diagnosis dipsticks for plague, cholera, and some forms of bacterial meningitis with the same technology.
Diarrhoeal diseases, caused by a wide range of pathogens, are ranked among the most deadly infectious diseases in the world, especially in developing countries in the tropics. Treatment differs according to the bacterium concerned. The standard diagnosis of these pathologies requires isolating and identifying the bacteria implicated, which is often difficult in developing countries. It is hence very important to have diagnostic tests that are simple, reliable, rapid, and easy to use in the field, especially in order to direct practitioners towards suitable treatment as quickly as possible.
Such tests have recently been developed to diagnose the most widespread form of bacillary dysentery, which is due to the Shigella flexneri 2a bacterium, as was shown by a study led by Farida Nato (Production of Recombinant Proteins and Antibodies Platform, Institut Pasteur, Paris), and Yves Germani from the Institut Pasteur International Network, who works in the joint Institut Pasteur-Inserm unit directed by Philippe Sansonetti.
Several species of Shigella cause bacillary dysentery, or shigellosis, which causes bloody diarrhoea. This pathology is responsible for approximately 165 million cases and more than 1 million deaths every year, affecting children under 5 years of age in more than 60% of the cases. But the majority of deaths is due to the endemic form of the infection, linked to Shigella flexneri, the dominant serotype of which in developing countries-where 99% of the shigellosis cases occur-is Shigella flexneri 2a.
Hence the researchers propose the rapid and reliable detection of the presence of Shigella flexneri 2a in patients suffering from diarrhoea: their test-based on an immunochromatography technique-is in the form of a dipstick inserted directly into a tube containing the patient’s stools. After 5-15 minutes, the appearance (or lack) of two red lines on the dipstick signals the presence (or absence) of the bacterium.
Evaluation of these dipsticks was performed in Vietnam, together with the Institut Pasteur of Ho Chi Minh City. It is continuing in the Institut Pasteur International Network (in Senegal, the Central African Republic, Madagascar, and Vietnam), in Chile, Bangladesh, and-in cooperation with the French Army-in Djibouti.
The researchers have also developed a similar test for the bacterium responsible for the epidemic form of shigellosis, Shigella dysenteriae 1, which is yet to be validated in the field.
Beyond this major pathology, we hope, in collaboration with the Institut Pasteur International Network, to develop tests on dipsticks against the major enteropathogenic agents of the tropics, declared Yves Germani. Our eventual objective is to have ’multiplex’ tests that would make it possible to detect in a single process the presence of the principal pathogens responsible for diarrhoeas".
- "Dipstick for rapid diagnosis of Shigella flexneri 2a in stool" : PLoS ONE, 18 April 2007
Faridabano Nato (1), Armelle Phalipon (2, 3), Lan Phuong Thi Nguyen (4), Tai The Diep (4), Philippe Sansonetti (2, 3), Yves Germani (2, 3)
1. Platform 5 - Production of Recombinant Proteins and Antibodies, Institut Pasteur, Paris, France
2. Molecular Microbial Pathogenesis Unit, Institut Pasteur, Paris, France
3. INSERM Unit 786 "Microbial Invasion and Colonization of Mucosa", Paris, France
4. Institut Pasteur, Ho Chi Minh City, Vietnam, 5International Network, Institut Pasteur, Paris, France