title: Development and evaluation of a dipstick diagnostic test for Neisseria meningitidis serogroup X.
abstract: The emergence of Neisseria meningitidis serogroup X (NmX) in the African meningitis belt has urged the development of diagnostic tools and vaccines for this serogroup, especially following the introduction of a conjugate vaccine against N. meningitidis serogroup A (NmA). We have developed and evaluated a new rapid diagnostic test (RDT) for detecting the capsular polysaccharide (cps) antigen of this emerging serogroup. Whole inactivated NmX bacteria were used to immunize rabbits. Following purification by affinity chromatography, the cpsX-specific IgG antibodies were utilized to develop an NmX-specific immunochromatography dipstick RDT. The test was validated against purified cpsX and meningococcal strains of different serogroups. Its performance was evaluated against that of PCR on a collection of 369 cerebrospinal fluid (CSF) samples obtained from patients living in countries within the meningitis belt (Cameroon, Côte d'Ivoire, and Niger) or in France. The RDT was highly specific for NmX strains. Cutoffs of 10(5) CFU/ml and 1 ng/ml were observed for the reference NmX strain and purified cpsX, respectively. Sensitivity and specificity were 100% and 94%, respectively. A high agreement between PCR and RDT (Kappa coefficient, 0.98) was observed. The RDT gave a high positive likelihood ratio and a low negative likelihood (0.07), indicating almost 100% probability of declaring disease or not when the test is positive or negative, respectively. This unique NmX-specific test could be added to the available set of RDT for the detection of meningococcal meningitis in Africa as a major tool to reinforce epidemiological surveillance after the introduction of the NmA conjugate vaccine.
authors.affiliation: Institut Pasteur, Invasive Bacterial Infection Unit, National Reference Centre for Meningococci, Paris, France WHO Collaborating Centre for Meningococci, Institut Pasteur, Paris, France Université Denis Diderot, Sorbonne Paris Cité, Paris, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Agnememel
authors.affiliation: Institut Pasteur, Plateforme d'Ingénierie des Anticorps (PFIA), Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Traincard
authors.affiliation: Institut Pasteur, Plateforme d'Ingénierie des Anticorps (PFIA), Paris, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dartevelle
authors.affiliation: Institut Pasteur, Unité de Chimie des Biomolécules, Paris, France CNRS UMR 3523, Institut Pasteur, Paris, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Mulard
authors.affiliation: Centre de Recherche Médicale et Sanitaire (CERMES), Niamey, Niger.
authors.forename: Ali Elhaji
authors.initials: AE
authors.lastname: Mahamane
authors.affiliation: Centre de Recherche Médicale et Sanitaire (CERMES), Niamey, Niger.
authors.forename: Odile Ouwe Missi
authors.initials: OO
authors.lastname: Oukem-Boyer
authors.affiliation: Institut Pasteur, Invasive Bacterial Infection Unit, National Reference Centre for Meningococci, Paris, France WHO Collaborating Centre for Meningococci, Institut Pasteur, Paris, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Denizon
authors.affiliation: Institut Pasteur de Côte d'Ivoire, Abidjan, Ivory Coast.
authors.forename: Adèle
authors.initials: A
authors.lastname: Kacou-N Douba
authors.affiliation: Institut Pasteur de Côte d'Ivoire, Abidjan, Ivory Coast.
authors.forename: Mireille
authors.initials: M
authors.lastname: Dosso
authors.affiliation: Centre Pasteur Annexe de Garoua, Garoua, Cameroon.
authors.forename: Bouba
authors.initials: B
authors.lastname: Gake
authors.affiliation: Centre Pasteur Annexe de Garoua, Garoua, Cameroon.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lombart
authors.affiliation: Institut Pasteur, Invasive Bacterial Infection Unit, National Reference Centre for Meningococci, Paris, France WHO Collaborating Centre for Meningococci, Institut Pasteur, Paris, France mktaha@pasteur.fr.
authors.forename: Muhamed-Kheir
authors.initials: MK
authors.lastname: Taha
mesh_terms: D000349:Africa; D000942:Antigens, Bacterial / Q000032:analysis; D002555:Cerebrospinal Fluid / Q000382:microbiology; D002846:Chromatography, Affinity / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005602:France; D006801:Humans; D008585:Meningitis, Meningococcal / Q000175:diagnosis* / Q000382:microbiology*; D009345:Neisseria meningitidis / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D065288:Serogroup
chemical_list: D000942:Antigens, Bacterial