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International audience; Meningococcal meningitis remains a life-threatening disease worldwide, with high prevalence in the sub-Saharan meningitis belt. A rapid diagnosis is crucial for implementing adapted antimicrobial treatment. We describe the performances of a new immunochromatographic test (MeningoSpeed, BioSpeedia, France) for detecting and grouping Neisseria meningitidis. Cerebrospinal fluids (CSFs) were collected from 5 African countries and France. For the rapid diagnostic test (RDT), the CSF sample was deposited on each of the 3 cassettes for a total volume of 90 μl. The results of the RDT were compared to those of a reference multiplex PCR assay detecting the major serogroups of N. meningitidis on 560 CSF specimens. Five specimens were found uninterpretable by RDT (0.9%). The results of interpretable specimens were as follows: 305 positive and 212 negative samples by both techniques, 14 positive by PCR only, and 24 positive by RDT only (sensitivity, specificity, and positive and negative predictive values of 92.7%, 93.8%, 95.6%, and 89.8%, respectively, with an accuracy of 93.2% and a kappa test of 0.89; P < 0.05). From 319 samples positive by PCR for serogroups A, C, W, X, or Y, the grouping results were concordant for 299 specimens (sensitivity of 93.0%, 74.4%, 98.1%, 100%, and 83.3% for serogroups A, C, W, X, and Y, respectively). The MeningoSpeed RDT exhibited excellent performances for the rapid detection of N. meningitidis antigens. It can be stored at room temperature, requires a minimal amount of CSF, is performed in 15 minutes or less, and is easy to use at bedside.

Worldwide, it is estimated that 140 million people suffer from shigellosis annually. The traditional identification of Shigella spp. by culture lacks sensitivity. Rapid diagnosis of shigellosis is important because it allows to engage appropriate antimicrobial treatment that shortens the duration and severity of the illness and reduces microbial carriage, thus the spread of infection in the community. Onestep immunochromatographic dipstick tests have been successfully developed at Institut Pasteur for Shigella spp., Shigella flexneri 2a, Shigella sonnei, and Shigella dysenteriae 1. The present work describes the evaluation of these four rapid diagnostic tests (RDT) that addressed the issue of rapid diagnosis of Shigella diarrhea and dysentery testing from bacterial cultures, stools, and rectal swabs which is usually how the specimen is often collected or received from the field or from remote settings. The evaluations have been performed in Chile, Democratic Republic of Congo, Senegal, Djibouti, Vietnam, India, and France, in dispensaries, in emergency room, on the field, in public health laboratories, and by the French Army. The dipstick method used requires minimal technical skill, and the test can be read between 5 and 15 minutes. Stool cultures and the immunochromatographic test showed concordant results in the comparative studies when RDT for S. sonnei was tested in Chile, Vietnam, India, and France; specificity (Sp) was 96% and sensitivity (Se) was 100%. When RDT for S. flexneri 2a was tested in Vietnam, Se was 91.5% and Sp was 99.2%. In Chile, Se was 83.3% and Sp was 100%. When RDT for S. dysenteriae 1 was tested in India, Vietnam, Senegal, and France by laboratory technicians and in Democratic Republic of Congo by a field technician, the Sp was 98.7% and the Se was 91.7%. In Chile, the initial finding for a simple RDT to diagnose Shigella spp. demonstrates its promising potential to become a powerful tool for case management and epidemiological surveys. Additionally, the dipsticks can be stored at room temperature in a humidity-proof plastic bag, making them easily transportable. Considering the potential impact these RDT have for the clinical management of the disease and for epidemiological studies, industrialization of these tests is in progress.

Nowadays, Rapid Diagnostic Tests (RDTs) are essential tools for an urgent response in infectious diseases. Many tests are available to search for different pathogens (HIV, group A streptococcus, plasmodium ...) in various biological samples (urine, cerebrospinal fluid or CSF, blood ...). The main advantages of this mode of diagnosis are speed, simplicity of implementation, including by non-specialists or outside a laboratory structure, and reasonable cost. In this “CIFRE” (industrial) thesis, we present three RDTs based on lateral flow immunochromatography (LFIA) that we contributed to develop and evaluate.The first TDR targets Neisseria meningitidis, a bacterium responsible for severe outbreaks of meningitis in resource-limited countries, in CSF samples. This RDT is the only LFIA-type commercial test that can detect 5 of the 6 major serogroups involved in the disease (A/C/W/X/Y). A study published under the authority of the meningococci reference centre at the Institut Pasteur of Paris showed the excellent performances of this test on nearly 560 CSF samples collected from 6 countries including 5 in Africa.The second TDR targets Streptococcus pneumoniae in urine and CSF; it is also intended to the diagnosis of bacterial meningitis. This test, coupled with the previous one, is the object of a multicentric study presently conducted in West Africa under cover of WHO.The third TDR is an avatar of the previous one but was dedicated to respiratory secretions. Called PneumoResp, it introduces the concept of semi-quantitative RDT. It proposes to perform the test on undiluted secretions and, in the case of positive result, on 1:100-diluted secretions. We present an algorithm (which is the object of a patent pending appraisal) that aims to differentiate S. pneumoniae carriage from invasive infection by this germ in children. Compared to conventional techniques (semi-quantitative culture and qPCR assays), the test performed on 196 respiratory specimens showed an excellent sensitivity and a very good negative predictive value, allowing to exclude or suspect an active S. pneumoniae infection as soon as the first day., Les tests de diagnostic rapide (TDR) sont aujourd’hui des outils indispensables pour une réponse urgente en pathologie infectieuse. De nombreux tests sont disponibles pour rechercher différents agents pathogènes (VIH, streptocoque du groupe A, plasmodium …) dans des prélèvements biologiques variés (urine, liquide cérébrospinal ou LCS, sang …). L’avantage de ce mode de diagnostic est leur rapidité, leur simplicité de mise en œuvre, y compris par des non-spécialistes ou à l’extérieur d’une structure de laboratoire, et leur coût raisonnable. Dans ce travail de thèse CIFRE, nous présentons trois TDR que nous avons contribué à développer et à évaluer, basés sur l’immunochromatographie à flux latéral (LFIA). Le premier TDR cible Neisseria meningitidis dans le LCS, bactérie responsable de redoutables épidémies de méningites dans les pays à ressources limitées. Ce TDR est le seul test commercial de type LFIA qui permette de détecter 5 des 6 principaux sérogroupes impliqués dans la maladie (A/C/W/X/Y). Une étude publiée sous l’égide du CNR des méningocoques à l’Institut Pasteur de Paris montre les excellentes performances de ce test sur près de 560 échantillons de LCS provenant de 6 pays. Le deuxième TDR cible Streptococcus pneumoniae dans l’urine et le LCS, également dans le cadre du diagnostic des méningites bactériennes. Ce test, couplé au précédent, fait l’objet d’une étude multicentrique en Afrique de l’ouest sous couvert de l’OMS. Le troisième TDR est un avatar du précédent dédié aux sécrétions respiratoires. Dénommé PneumoResp, il introduit le concept de TDR semi-quantitatif en proposant d’effectuer le test sur sécrétions non diluées et, en cas de résultat positif, sur sécrétions diluées au 1 :100ème. Nous proposons un algorithme (qui fait l’objet d’un brevet en cours d’expertise) qui vise à différencier le portage de l’infection invasive à S. pneumoniae chez l’enfant. Par rapport aux techniques conventionnelles (culture semi-quantitative et qPCR), nous montrons sur quelque 200 échantillons respiratoires une excellente sensibilité et une très bonne valeur prédictive négative de ce test pour exclure ou suspecter une infection active à S. pneumoniae chez l’enfant dès le premier jour.

Nowadays, Rapid Diagnostic Tests (RDTs) are essential tools for an urgent response in infectious diseases. Many tests are available to search for different pathogens (HIV, group A streptococcus, plasmodium ...) in various biological samples (urine, cerebrospinal fluid or CSF, blood ...). The main advantages of this mode of diagnosis are speed, simplicity of implementation, including by non-specialists or outside a laboratory structure, and reasonable cost. In this “CIFRE” (industrial) thesis, we present three RDTs based on lateral flow immunochromatography (LFIA) that we contributed to develop and evaluate.The first TDR targets Neisseria meningitidis, a bacterium responsible for severe outbreaks of meningitis in resource-limited countries, in CSF samples. This RDT is the only LFIA-type commercial test that can detect 5 of the 6 major serogroups involved in the disease (A/C/W/X/Y). A study published under the authority of the meningococci reference centre at the Institut Pasteur of Paris showed the excellent performances of this test on nearly 560 CSF samples collected from 6 countries including 5 in Africa.The second TDR targets Streptococcus pneumoniae in urine and CSF; it is also intended to the diagnosis of bacterial meningitis. This test, coupled with the previous one, is the object of a multicentric study presently conducted in West Africa under cover of WHO.The third TDR is an avatar of the previous one but was dedicated to respiratory secretions. Called PneumoResp, it introduces the concept of semi-quantitative RDT. It proposes to perform the test on undiluted secretions and, in the case of positive result, on 1:100-diluted secretions. We present an algorithm (which is the object of a patent pending appraisal) that aims to differentiate S. pneumoniae carriage from invasive infection by this germ in children. Compared to conventional techniques (semi-quantitative culture and qPCR assays), the test performed on 196 respiratory specimens showed an excellent sensitivity and a very good negative predictive value, allowing to exclude or suspect an active S. pneumoniae infection as soon as the first day.; Les tests de diagnostic rapide (TDR) sont aujourd’hui des outils indispensables pour une réponse urgente en pathologie infectieuse. De nombreux tests sont disponibles pour rechercher différents agents pathogènes (VIH, streptocoque du groupe A, plasmodium …) dans des prélèvements biologiques variés (urine, liquide cérébrospinal ou LCS, sang …). L’avantage de ce mode de diagnostic est leur rapidité, leur simplicité de mise en œuvre, y compris par des non-spécialistes ou à l’extérieur d’une structure de laboratoire, et leur coût raisonnable. Dans ce travail de thèse CIFRE, nous présentons trois TDR que nous avons contribué à développer et à évaluer, basés sur l’immunochromatographie à flux latéral (LFIA). Le premier TDR cible Neisseria meningitidis dans le LCS, bactérie responsable de redoutables épidémies de méningites dans les pays à ressources limitées. Ce TDR est le seul test commercial de type LFIA qui permette de détecter 5 des 6 principaux sérogroupes impliqués dans la maladie (A/C/W/X/Y). Une étude publiée sous l’égide du CNR des méningocoques à l’Institut Pasteur de Paris montre les excellentes performances de ce test sur près de 560 échantillons de LCS provenant de 6 pays. Le deuxième TDR cible Streptococcus pneumoniae dans l’urine et le LCS, également dans le cadre du diagnostic des méningites bactériennes. Ce test, couplé au précédent, fait l’objet d’une étude multicentrique en Afrique de l’ouest sous couvert de l’OMS. Le troisième TDR est un avatar du précédent dédié aux sécrétions respiratoires. Dénommé PneumoResp, il introduit le concept de TDR semi-quantitatif en proposant d’effectuer le test sur sécrétions non diluées et, en cas de résultat positif, sur sécrétions diluées au 1 :100ème. Nous proposons un algorithme (qui fait l’objet d’un brevet en cours d’expertise) qui vise à différencier le portage de l’infection invasive à S. pneumoniae chez l’enfant. Par rapport aux techniques conventionnelles (culture semi-quantitative et qPCR), nous montrons sur quelque 200 échantillons respiratoires une excellente sensibilité et une très bonne valeur prédictive négative de ce test pour exclure ou suspecter une infection active à S. pneumoniae chez l’enfant dès le premier jour.