Dipstick test for rapid diagnosis of Shigella dysenteriae 1 in bacterial cultures and its potential use on stool samples.

Neelam Taneja (1) , Faridabano Nato (2) , Sylvie Dartevelle (2) , Jean Marie Sire (3) , Benoit Garin (3) , Lan Nguyen Thi Phuong (4) , Tai The Diep (4) , Jean Christophe Shako (5) , François Bimet (6) , Ingrid Filliol (7) , Jean-Jacques Muyembe (8) , Marie Noëlle Ungeheuer (9) , Catherine Ottone (9) , Philippe Sansonetti (10, 11) , Yves Germani (12)

1 Department of Medical Microbiology
2 Production de Protéines Recombinantes et d'Anticorps (Plate-Forme)
3 Laboratoire de Biologie Médicale [Dakar, Sénégal]
4 Institut Pasteur d'Ho Chi Minh Ville
5 Antenne Médicale de Bunia
6 CRBIP - Centre de Ressources biologiques de l'Institut Pasteur - Biological Resource Center of the Institut Pasteur
7 CNR - Centre National de Référence des Escherichia coli et Shigella - Bactéries Pathogènes Entériques
8 INRB - Institut National de Recherche Biomédicale [Kinshasa]
9 ICAReB - Investigation Clinique et d’Accès aux Ressources Biologiques (Plate-forme) - Clinical Investigation and Access to BioResources
10 Pathogénie Microbienne Moléculaire
11 Collège de France - Chaire Microbiologie et Maladies infectieuses
12 BioSpeedia Société par Actions Simplifée

BACKGROUND: We describe a test for rapid detection of S. dysenteriae 1 in bacterial cultures and in stools, at the bedside of patients. METHODOLOGY/PRINCIPAL FINDINGS: The test is based on the detection of S. dysenteriae 1 lipopolysaccharide (LPS) using serotype 1-specific monoclonal antibodies coupled to gold particles and displayed on a one-step immunochromatographic dipstick. A concentration as low as 15 ng/ml of LPS was detected in distilled water and in reconstituted stools in 10 minutes. In distilled water and in reconstituted stools, an unequivocal positive reaction was obtained with 1.6×10⁶ CFU/ml and 4.9×10⁶ CFU/ml of S. dysenteriae 1, respectively. Optimal conditions to read the test have been determined to limit the risk of ambiguous results due to appearance of a faint yellow test band in some negative samples. The specificity was 100% when tested with a battery of Shigella and unrelated strains in culture. When tested on 328 clinical samples in India, Vietnam, Senegal and France by laboratory technicians and in Democratic Republic of Congo by a field technician, the specificity (312/316) was 98.7% (95% CI:96.6-99.6%) and the sensitivity (11/12) was 91.7% (95% CI:59.8-99.6%). Stool cultures and the immunochromatographic test showed concordant results in 98.4 % of cases (323/328) in comparative studies. Positive and negative predictive values were 73.3% (95% CI:44.8-91.1%) and 99.7% (95% CI:98-100%). CONCLUSION: The initial findings presented here for a simple dipstick-based test to diagnose S. dysenteriae 1 demonstrates its promising potential to become a powerful tool for case management and epidemiological surveys.

Domaines: Sciences du Vivant [q-bio]

Neelam Taneja, Faridabano Nato, Sylvie Dartevelle, Jean Marie Sire, Benoit Garin, et al.. Dipstick test for rapid diagnosis of Shigella dysenteriae 1 in bacterial cultures and its potential use on stool samples.. PLoS ONE, 2011, 6 (10), pp.e24830. ⟨10.1371/journal.pone.0024830⟩. ⟨pasteur-00836503⟩