Biological differences between FIM2 and FIM3 fimbriae of Bordetella pertussis: not just the serotype.

INTRODUCTION: Bordetella pertussis still circulates worldwide despite vaccination. Fimbriae are components of some acellular pertussis vaccines. Population fluctuations of B. pertussis fimbrial serotypes (FIM2 and FIM3) are observed, and fim3 alleles (fim3-1 [clade 1] and fim3-2 [clade 2]) mark a major phylogenetic subdivision of B. pertussis. OBJECTIVES: To compare microbiological characteristics and expressed protein profiles between fimbrial serotypes FIM2 and FIM3 and genomic clades. METHODS: A total of 19 isolates were selected. Absolute protein abundance of the main virulence factors, autoagglutination and biofilm formation, bacterial survival in whole blood, induced blood cell cytokine secretion, and global proteome profiles were assessed. RESULTS: Compared to FIM3, FIM2 isolates produced more fimbriae, less cellular pertussis toxin subunit 1 and more biofilm, but auto-agglutinated less. FIM2 isolates had a lower survival rate in cord blood, but induced higher levels of IL-4, IL-8 and IL-1ß secretion. Global proteome comparisons uncovered 15 differentially produced proteins between FIM2 and FIM3 isolates, involved in adhesion and metabolism of metals. FIM3 isolates of clade 2 produced more FIM3 and more biofilm compared to clade 1. CONCLUSION: FIM serotype and fim3 clades are associated with proteomic and other biological differences, which may have implications on pathogenesis and epidemiological emergence.

Association between the COVID-19 pandemic and pertussis derived from multiple nationwide data sources, France, 2013 to 2020.

BackgroundInterventions to mitigate the COVID-19 pandemic may impact other respiratory diseases.AimsWe aimed to study the course of pertussis in France over an 8-year period including the beginning of the COVID-19 pandemic and its association with COVID-19 mitigation strategies, using multiple nationwide data sources and regression models.MethodsWe analysed the number of French pertussis cases between 2013 and 2020, using PCR test results from nationwide outpatient laboratories (Source 1) and a network of the paediatric wards from 41 hospitals (Source 2). We also used reports of a national primary care paediatric network (Source 3). We conducted a quasi-experimental interrupted time series analysis, relying on negative binomial regression models. The models accounted for seasonality, long-term cycles and secular trend, and included a binary variable for the first national lockdown (start 16 March 2020).ResultsWe identified 19,039 pertussis cases from these data sources. Pertussis cases decreased significantly following the implementation of mitigation measures, with adjusted incidence rate ratios of 0.10 (95% CI: 0.04-0.26) and 0.22 (95% CI: 0.07-0.66) for Source 1 and Source 2, respectively. The association was confirmed in Source 3 with a median of, respectively, one (IQR: 0-2) and 0 cases (IQR: 0-0) per month before and after lockdown (p = 0.0048).ConclusionsThe strong reduction in outpatient and hospitalised pertussis cases suggests an impact of COVID-19 mitigation measures on pertussis epidemiology. Pertussis vaccination recommendations should be followed carefully, and disease monitoring should be continued to detect any resurgence after relaxation of mitigation measures.

Effect of change in vaccine schedule on pertussis epidemiology in France: a modelling and serological study.

BACKGROUND: In April-May, 2013, France modified its pertussis vaccination schedule, which uses the acellular pertussis vaccine, from three primary doses at 2, 3, and 4 months of age and a first booster at 16-18 months of age (former schedule) to two primary doses at 2 and 4 months of age and a first booster at 11 months of age (new schedule). We aimed to assess the subsequent effect of the vaccine schedule change on pertussis epidemiology in France. METHODS: In this modelling study, using data collected between Jan 1, 2012, and Dec 31, 2019, from French national surveillance sources, we analysed the PCR test results of nasopharyngeal swabs collected from symptomatic outpatients aged 2-20 years with suspected pertussis. We developed a negative binomial regression model for the number of confirmed pertussis cases by year and age to assess the relative risks of pertussis depending on vaccine schedule. The linear predictor included the year, the age group, the population size, and a proxy of waning immunity. We tested different models in which waning immunity could vary with vaccine schedule and type of primary vaccine. The models were fitted to the 2012-18 data via Bayesian Markov chain Monte Carlo sampling, and the 2019 data were left out for external model validation. We also compared the anti-pertussis toxin (PT) antibody concentrations in leftover sera from children not tested for pertussis or recent respiratory tract infection aged 2-5 years born before and after the vaccine schedule change. FINDINGS: We collected data on 7493 confirmed cases of pertussis. The model that best fitted the 2012-18 epidemiological data supported a faster waning of immunity following vaccination with the new vaccine schedule. 3 years after vaccination, the risk of developing pertussis was 1·7 (95% CI 1·4-2·0) times higher for children vaccinated according to the new schedule than those vaccinated according to the former schedule. The model correctly predicted the age distribution of cases in 2019. Geometric mean concentrations (GMC) of anti-PT IgG were 50% lower in children aged 2 years vaccinated with the new schedule (GMC=5·85 IU/mL [95% CI 4·08-8·39]) than in children of the same age vaccinated with the former schedule (GMC=11·62 IU/mL [95% CI 9·05-14·92]; p=0·0016), and 43% lower in children aged 3 years vaccinated with the new schedule (GMC=3·88 IU/mL [95% CI 2·82-5·34]) than those with the former schedule (GMC=6·80 IU/mL [95% CI 4·77-9·70]; p=0·026). INTERPRETATION: A shorter-lived protection induced by the new vaccine schedule recommended in France since 2013 is associated with an increase of pertussis cases in children aged 2-5 years. If similar findings are observed in other countries and clinical trials, these findings should be considered in future pertussis vaccination policies. FUNDING: INCEPTION, Labex-IBEID, Institut Pasteur, and Santé Publique France.

Evolution of Bordetella pertussis over a 23-year period in France, 1996 to 2018.

BackgroundBordetella pertussis is the main agent of whooping cough. Vaccination with acellular pertussis vaccines has been largely implemented in high-income countries. These vaccines contain 1 to 5 antigens: pertussis toxin (PT), filamentous haemagglutinin (FHA), pertactin (PRN) and/or fimbrial proteins (FIM2 and FIM3). Monitoring the emergence of B. pertussis isolates that might partially escape vaccine-induced immunity is an essential component of public health strategies to control whooping cough.AimWe aimed to investigate temporal trends of fimbriae serotypes and vaccine antigen-expression in B. pertussis over a 23-year period in France (1996-2018).MethodsIsolates (n = 2,280) were collected through hospital surveillance, capturing one third of hospitalised paediatric pertussis cases. We assayed PT, FHA and PRN production by Western blot (n = 1,428) and fimbriae production by serotyping (n = 1,058). Molecular events underlying antigen deficiency were investigated by genomic sequencing.ResultsThe proportion of PRN-deficient B. pertussis isolates has increased steadily from 0% (0/38) in 2003 to 48.4% (31/64) in 2018 (chi-squared test for trend, p < 0.0001), whereas only 5 PT-, 5 FHA- and 9 FIM-deficient isolates were found. Impairment of PRN production was predominantly due to IS481 insertion within the prn gene or a 22 kb genomic inversion involving the prn promoter sequence, indicative of convergent evolution. FIM2-expressing isolates have emerged since 2011 at the expense of FIM3.ConclusionsB. pertussis is evolving through the rapid increase of PRN-deficient isolates and a recent shift from FIM3 to FIM2 expression. Excluding PRN, the loss of vaccine antigen expression by circulating B. pertussis isolates is epidemiologically insignificant.

Distinctive Features of Kawasaki Disease Following SARS-CoV-2 Infection: a Controlled Study in Paris, France.

BACKGROUND: An outbreak of multisystem inflammatory syndrome in children, including Kawasaki disease (KD), emerged during COVID-19 pandemic. We explored whether Kawasaki-like disease (KD), when associated with confirmed SARS-CoV-2 infection, has specific characteristics. METHODS: We included children and adolescents with KD criteria admitted in the department of general pediatrics of a university hospital in Paris, France, between January 1, 2018, and May 26, 2020. The incidence of KD was compared between the outbreak and a pre-outbreak control period (January 1, 2018, to April 25). Characteristics of patients with positive SARS-CoV-2 testing (KD-SARS-CoV-2) were compared to those of the pre-outbreak period (classic KD). RESULTS: A total of 30 and 59 children with KD were admitted during the outbreak and pre-outbreak periods, respectively (incidence ratio 13.2 [8.3-21.0]). During the outbreak, 23/30 (77%) children were diagnosed as KD-SARS-CoV-2. When compared with patients with classic KD, those with KD-SARS-CoV-2 were more frequently of sub-Saharan African ancestry (OR 4.4 [1.6-12.6]) and older (median 8.2 vs. 4.0 years, p < 0.001), had more often initial gastrointestinal (OR 84 [4.9-1456]) and neurological (OR 7.3 [1.9-27.7] manifestations, and shock syndrome (OR 13.7 [4.2-45.1]). They had significantly higher CRP and ferritin levels. Noticeably, they had more frequently myocarditis (OR 387 [38-3933]). CONCLUSIONS: Children and adolescents with KD-SARS-CoV-2 have specific features when compared with those with classic KD. These findings should raise awareness and facilitate the study of their pathogenesis.

Scurvy: A New Old Cause of Skeletal Pain in Young Children.

We report 3 cases of scurvy in children that occurred during a short period (2018) in a general pediatrics unit of a tertiary hospital for children in Paris. All children were around 3 years of age and were admitted for skeletal pain and altered general state, which mimicked infectious or malignant diseases. Their selective diet was not the prominent issue. The diagnosis of scurvy was delayed, after too many unnecessary examinations and medications. Bone imaging findings (X-ray and MRI) were a posteriori considered typical, but lesions were not easily identified as scurvy lesions because scurvy is not well-known by pediatricians and radiologists who should be mindful of this historical diagnosis.

COVID-19-Related Fatalities and Intensive-Care-Unit Admissions by Age Groups in Europe: A Meta-Analysis.

Objectives: Precise international estimates of the age breakdown of COVID-19-related deaths and intensive-care-unit (ICU) admissions are lacking. We evaluated the distribution of COVID-19-related fatalities and ICU admissions by age groups in Europe. Materials and methods: On April 6, 2020, we systematically reviewed official COVID-19-related data from 32 European countries. We included countries that provided data regarding more than 10 COVID-19-related deaths stratified by age according to pre-specified age groups (i.e., <40, 40-69, ≥70 years). We used random-effects meta-analysis to summarize the data. Results: Thirteen European countries were included in the review, for a total of 31,864 COVID-19-related deaths (range: 27-14,381 per country). In the main meta-analysis (including data from Germany, Hungary, Italy, The Netherlands, Portugal, Spain, Switzerland; 21,522 COVID-19-related fatalities), the summary proportions of individuals <40, 40-69, and ≥70 years old among all COVID-19-related deaths were 0.1% (0.0-0.2; I 2 28.6%), 13.0% (10.8-15.4; I 2 91.5%), and 86.6% (84.2-88.9; I 2 91.5%), respectively. ICU data were available for four countries (France, Greece, Spain, Sweden). The summary proportions of individuals around <40-50, around 40-69, and around ≥60-70 years old among all COVID-19-related ICU admissions were 5.4% (3.4-7.8; I 2 89.0%), 52.6% (41.8-63.3; I 2 98.1%), and 41.8% (32.0-51.9; I 2 99%), respectively. Conclusions: People under 40 years old represent a small fraction of most severe COVID-19 cases in Europe. These results may help health authorities respond to public concerns and guide future physical distancing and mitigation strategies. Specific measures to protect older people should be considered.

Bordetella parapertussis Bacteremia: Clinical Expression and Bacterial Genomics.

Whooping cough's primary etiological agent is Bordetella pertussis. The closely related Bordetella parapertussis rarely causes severe disease. Here we report an unusual case of bacteremia caused by B. parapertussis, review the literature, and characterize the genomic sequence of the bacterial isolate in comparison with B. parapertussis isolates from respiratory infections.

Algorithms to Define Abnormal Growth in Children: External Validation and Head-To-Head Comparison.

Background: Growth monitoring of apparently healthy children aims at early detection of serious conditions by use of both clinical expertise and algorithms that define abnormal growth. The seven existing algorithms provide contradictory definitions of growth abnormality and have a low level of validation. Objective: An external validation study with head-to-head comparison of the seven algorithms combined with study of the impact of use of the World Health Organization (WHO) vs national growth charts on algorithm performance. Design: With a case-referent approach, we retrospectively applied all algorithms to growth data for children with Turner syndrome, GH deficiency, or celiac disease (n = 341) as well as apparently healthy children (n = 3406). Sensitivity, specificity, and theoretical reduction in time to diagnosis for each algorithm were calculated for each condition by using the WHO or national growth charts. Results: Among the two algorithms with high specificity (>98%), the Grote clinical decision rule had higher sensitivity than the Coventry consensus (4.6% to 54% vs 0% to 8.9%, P < 0.05) and offered better theoretical reduction in time to diagnosis (median: 0.0 to 0.9 years vs 0 years, P < 0.05). Sensitivity values were significantly higher with the WHO than national growth charts at the expense of specificity. Conclusion: The Grote clinical decision rule had the best performance for early detection of the three studied diseases, but its limited potential for reducing time to diagnosis suggests the need for better-performing algorithms based on appropriate growth charts.

An ADAM-10 dependent EPCR shedding links meningococcal interaction with endothelial cells to purpura fulminans.

Purpura fulminans is a deadly complication of Neisseria meningitidis infections due to extensive thrombosis of microvessels. Although a Disseminated Intra-vascular Coagulation syndrome (DIC) is frequently observed during Gram negative sepsis, it is rarely associated with extensive thrombosis like those observed during meningococcemia, suggesting that the meningococcus induces a specific dysregulation of coagulation. Another specific feature of N. meningitidis pathogenesis is its ability to colonize microvessels endothelial cells via type IV pili. Importantly, endothelial cells are key in controlling the coagulation cascade through the activation of the potent anticoagulant Protein C (PC) thanks to two endothelial cell receptors among which the Endothelial Protein C Receptor (EPCR). Considering that congenital or acquired deficiencies of PC are associated with purpura fulminans, we hypothesized that a defect in the activation of PC following meningococcal adhesion to microvessels is responsible for the thrombotic events observed during meningococcemia. Here we showed that the adhesion of N. meningitidis on endothelial cells results in a rapid and intense decrease of EPCR expression by inducing its cleavage in a process know as shedding. Using siRNA experiments and CRISPR/Cas9 genome edition we identified ADAM10 (A Disintegrin And Metalloproteinase-10) as the protease responsible for this shedding. Surprisingly, ADAM17, the only EPCR sheddase described so far, was not involved in this process. Finally, we showed that this ADAM10-mediated shedding of EPCR induced by the meningococcal interaction with endothelial cells was responsible for an impaired activation of Protein C. This work unveils for the first time a direct link between meningococcal adhesion to endothelial cells and a severe dysregulation of coagulation, and potentially identifies new therapeutic targets for meningococcal purpura fulminans.