DIAGNOSTIC BIOLOGIQUE DE LA BRUCELLOSE HUMAINE: COMPARAISON DE DEUX TECHNIQUES DE SEROAGGLUTINATION

objective: Evaluate the technical characteristics of two agglutination techniques used for the detection of serum antibodies of Brucella. Material and methods: The search for Brucella antibodies was performed in 100 serum samples. They come from patients with brucellosis was suspected on clinical and epidemiological criteria. The average age was 31 years with a standard deviation of 1.5 and a sex ratio (M / W) is equal to 2. The two methods used are (manual): 1- BRUCELLACAPT® (Vircell,Spain) 2- ROSE BENGAL ® (Bio-Rad, France). Results: The results showed a concordance between the two techniques of 92% (80% negative results and 12% positive), and discrepancy of 8%. Conclusion: Discordant results demonstrate the need to always integrate the  approach diagnostic of a clinical and epidemiological data associated with biological data, and secondly, to take into account the  threshold value of detection of serological markers of the technique used.Objectif : Evaluer les caractéristiques de deux techniques de séroagglutination  pour la détection des anticorps sériques anti-Brucella. Matériel et méthodes : La recherche des anticorps anti Brucella a été effectuée sur 100 échantillons de sérums,  provenant de patients  chez qui la brucellose a été suspectée sur des critères cliniques et épidémiologiques. La moyenne d’âge est de 31 ans avec un écart type de 1,5 et un sex-ratio (H/F) de 2. Les deux méthodes de séroagglutination utilisées (manuelles) sont : 1- BRUCELLACAPT® (Vircell,Espagne) 2- ROSE BENGALE® (Bio Rad, France). Résultats : Les résultats  ont montré une concordance entre les deux techniques de 92% (80% négatifs et 12% positifs), et une disconcordance de 8%. Conclusion : Les résultats discordants démontrent la nécessité d’intégrer à la démarche diagnostic, les données cliniques, épidémiologiques,  l’évolution de la maladie, ainsi que les données biologiques et  de prendre en considération la valeur seuil  de détection des marqueurs sérologiques de la technique utilisée

COMPARAISON DE DEUX TECHNIQUES IMMUNOENZYMATIQUES ELISA POUR LA DETECTION DES ANTICORPS IgG SERIQUES ANTIRUBEOLIQUES

OBJECTIF: Il s’agit d’évaluer les caractéristiques de deux techniques immunoenzymatiques ELISA (principe, performances et limites) pour la détection des IgG sériques antirubéolique. MATERIEL ET METHODES: L a recherche des IgG antirubéoliques a été effectuée dans 100 échantillons de sérums recueillis dans le laboratoire d’immunosérologie du CHU Ibn Rochd de Casablanca. Ils proviennent de patients hospitalisés et de consultants externes du CHU. Il s’agit pour la plupart de jeunes femmes (85%) et de nouveaux nés (12%). Les deux méthodes immunoenzymatiques ELISA utilisées sont : 1- kit Vircell®Spain (technique manuelle) 2- AxsymAbbott®USA (technique microparticulaire automatisée). RESULTATS: Les résultats sérologiques pour la détection des anticorps IgG antirubéolique ont montré une concordance entre les deux techniques de 94% (90% des résultats positifs et 4% négatifs et une discordance de 6%. CONCLUSION: Même si la concordance entre les deux techniques est de 94%, les résultats discordants démontrent la nécessité d’intégrer toujours la démarche diagnostique, d’une part les données cliniques associées aux données biologiques, et d‘autres part, de prendre en considération la valeur seuil de détection des marques sérologiques spécifiques de la technique utilisée, ainsi que la qualité des échantillons testés

Chlamydia trachomatis ompA Variants in Trachoma: What Do They Tell Us?

Trachoma is an important cause of blindness resulting from transmission of the bacterium Chlamydia trachomatis. One way to understand better how this infection is transmitted and how the human immune system controls it is to study the strains of bacteria associated with infection. Comparing strains before and after treatment might help us learn if someone has a new infection or the same one as before. Identifying differences between disease-causing strains should help us understand how infection leads to disease and how the human host defences work. We chose to study variation in the chlamydial gene ompA because it determines the protein MOMP, one of the leading candidates for inclusion in a vaccine to prevent trachoma. If immunity to MOMP is important in natural trachoma infections, we would expect to find evidence of this in the way the strains varied. We did not find this, but instead found that two common strains seemed to cause different types of disease. Although their MOMPs were very slightly different, this did not really explain the differences. We conclude that methods of typing strains going beyond the ompA gene will be needed to help us understand the interaction between Chlamydia and its human host

Epidemiology of Chlamydia trachomatis in the Middle East and north Africa: a systematic review, meta-analysis, and meta-regression.

BACKGROUND: The epidemiology of Chlamydia trachomatis in the Middle East and north Africa is poorly understood. We aimed to provide a comprehensive epidemiological assessment of C trachomatis infection in the Middle East and north Africa. METHODS: We did a systematic review of C trachomatis infection as well as a meta-analysis and meta-regression of C trachomatis prevalence. We searched PubMed and Embase, as well as regional and national databases up to March 13, 2019, using broad search terms with no language or year restrictions. Any document or report including biological measures for C trachomatis prevalence or incidence was eligible for inclusion. We extracted all measures of current (genital or rectal), recent, and ever infection with C trachomatis. We estimated pooled average prevalence in different populations using random-effects meta-analysis. Factors associated with prevalence and sources of between-study heterogeneity were determined using meta-regression. FINDINGS: We identified a total of 1531 citations, of which 255 reports contributed to 552 C trachomatis prevalence measures from 20 countries. No incidence measures were identified. Pooled prevalence of current genital infection was 3·0% (95% CI 2·3-3·8) in general populations, 2·8% (1·0-5·2) in intermediate-risk populations, 13·2% (7·2-20·7) in female sex workers, 11·3% (9·0-13·7) in infertility clinic attendees, 12·4% (7·9-17·7) in women with miscarriage, 12·4% (9·4-15·7) in symptomatic women, and 17·4% (12·5-22·8) in symptomatic men. Pooled prevalence of current rectal infection was 7·7% (4·2-12·0) in men who have sex with men. Substantial between-study heterogeneity was found. Multivariable meta-regression explained 29·0% of variation. Population type was most strongly associated with prevalence. Additional associations were found with assay type, sample size, country, and sex, but not with sampling methodology or response rate (about 90% of studies used convenience sampling and >75% had unclear response rate). There was no evidence for temporal variation in prevalence between 1982 and 2018. INTERPRETATION: C trachomatis prevalence in the Middle East and north Africa is similar to other regions, but higher than expected given its sexually conservative norms. High prevalence in infertility clinic attendees and in women with miscarriage suggests a potential role for C trachomatis in poor reproductive health outcomes in this region. FUNDING: National Priorities Research Program from the Qatar National Research Fund (a member of Qatar Foundation)

Evolution, phylogeny, and molecular epidemiology of Chlamydia

The Chlamydiaceae are a family of obligate intracellular bacteria characterized by a unique biphasic developmental cycle. It encompasses the single genus Chlamydia, which involves nine species that affect a wide range of vertebral hosts, causing infections with serious impact on human health (mainly due to Chlamydia trachomatis infections) and on farming and veterinary industries. It is believed that Chlamydiales originated 700 mya, whereas C. trachomatis likely split from the other Chlamydiaceae during the last 6 mya. This corresponds to the emergence of modern human lineages, with the first descriptions of chlamydial infections as ancient as four millennia. Chlamydiaceae have undergone a massive genome reduction, on behalf of the deletional bias ‘‘use it or lose it’’, stabilizing at 1–1.2 Mb and keeping a striking genome synteny. Their phylogeny reveals species segregation according to biological properties, with huge differences in terms of host range, tissue tropism, and disease outcomes. Genome differences rely on the occurrence of mutations in the >700 orthologous genes, as well as on events of recombination, gene loss, inversion, and paralogous expansion, affecting both a hypervariable region named the plasticity zone, and genes essentially encoding polymorphic and transmembrane head membrane proteins, type III secretion effectors and some metabolic pathways. Procedures for molecular typing are still not consensual but have allowed the knowledge of molecular epidemiology patterns for some species as well as the identification of outbreaks and emergence of successful clones for C. trachomatis. This manuscript intends to provide a comprehensive review on the evolution, phylogeny, and molecular epidemiology of Chlamydia.This work was supported by the grants PTDC/SAU-MII/099623/2008 from Fundação para a Ciência e a Tecnologia (FCT) and ERAPTG/0004/2010 from FCT in the frame of ERA-NET PathoGenoMics (to J.P.G). A.N. is a recipient of a FCT post-doctoral fellowship (SFRH/BPD/75295/2010)