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Search Results: 1 - 10 of 2184 matches for " Didier Guillemot "
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Impact of Capsular Switch on Invasive Pneumococcal Disease Incidence in a Vaccinated Population
Laura Temime, Pierre-Yves Boelle, Lulla Opatowski, Didier Guillemot
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003244
Abstract: Background Despite the dramatic decline in the incidence of invasive pneumococcal disease (IPD) observed since the introduction of conjugate vaccination, it is feared that several factors may undermine the future effectiveness of the vaccines. In particular, pathogenic pneumococci may switch their capsular types and evade vaccine-conferred immunity. Methodology/Principal Findings Here, we first review the literature and summarize the available epidemiological data on capsular switch for S. pneumoniae. We estimate the weekly probability that a persistently carried strain may switch its capsule from four studies, totalling 516 children and 6 years of follow-up, at 1.5×10?3/week [4.6×10?5–4.8×10?3/week]. There is not enough power to assess an increase in this frequency in vaccinated individuals. Then, we use a mathematical model of pneumococcal transmission to quantify the impact of capsular switch on the incidence of IPD in a vaccinated population. In this model, we investigate a wide range of values for the frequency of vaccine-selected capsular switch. Predictions show that, with vaccine-independent switching only, IPD incidence in children should be down by 48% 5 years after the introduction of the vaccine with high coverage. Introducing vaccine-selected capsular switch at a frequency up to 0.01/week shows little effect on this decrease; yearly, at most 3 excess cases of IPD per 106 children might occur due to switched pneumococcal strains. Conclusions Based on all available data and model predictions, the existence of capsular switch by itself should not impact significantly the efficacy of pneumococcal conjugate vaccination on IPD incidence. This optimistic result should be tempered by the fact that the selective pressure induced by the vaccine is currently increasing along with vaccine coverage worldwide; continued surveillance of pneumococcal populations remains of the utmost importance, in particular during clinical trials of the new conjugate vaccines.
Did Media Attention of the 2009 A(H1N1) Influenza Epidemic Increase Outpatient Antibiotic Use in France?: A Time-Series Analysis
Adeline Bernier, Caroline Ligier, Didier Guillemot, Laurence Watier
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069075
Abstract: Background In France, the 2009 A(H1N1) influenza epidemic occurred between September 2009 and January 2010. Sparking widespread controversy, it was intensely reported in the media. Despite therapeutic inefficacy, antibiotic consumption and viral respiratory infections are positively correlated, particularly in France, where antibiotic overconsumption is well-known. We first determined the period when media coverage was high, and then compared, during this period, observed outpatient antibiotic consumption to estimated outpatient antibiotic consumption “without media attention”. Materials and Methods To evaluate media coverage, two online databases were consulted: Factiva and Europresse. To quantify outpatient antibiotic consumption, we used data on reimbursements of outpatient systemic antibiotics from the computerized databases of the two main National Health Insurance agencies. Influenza-like syndromes data came from the French GPs Sentinelles Network. Weekly time-series of antibiotic consumption were modeled by autoregressive moving-average models with exogenous inputs and interventions. Analyses were computed for the entire series and by age group (0–5, 6–15, 16–60, and >60 years). Results Media coverage was intense between April 2009 and January 2010. No effect on total outpatient antibiotic consumption was observed during the whole mediatic period. However, during the epidemic in France (September 2009-January 2010), we found an antibiotic underconsumption for the entire series, 0–5 and >60 years. Additionally, at the beginning of the pandemic, when cases were still outside France (June 2009-August 2009), we found an antibiotic overconsumption for patients >16 years. Conclusion The early period of A(H1N1) virus circulation compared with seasonal influenza or an overdeclaration of ILS cases might explain the antibiotic underconsumption observed during the period of active A(H1N1) virus transmission in France. At the pandemic onset, when uncertainty was high, the overconsumption observed for individuals >16 years might have been caused by alarmist media reporting. Additional analyses are needed to understand the determinants of antibiotic consumption during this period.
Major Role for Amphotericin B–Flucytosine Combination in Severe Cryptococcosis
Fran?oise Dromer, Claire Bernede-Bauduin, Didier Guillemot, Olivier Lortholary, for the French Cryptococcosis Study Group
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002870
Abstract: Background The Infectious Diseases Society of America published in 2000 practical guidelines for the management of cryptococcosis. However, treatment strategies have not been fully validated in the various clinical settings due to exclusion criteria during therapeutic trials. We assessed here the optimal therapeutic strategies for severe cryptococcosis using the observational prospective CryptoA/D study after analyzing routine clinical care of cryptococcosis in university or tertiary care hospitals. Methodology/Principal Findings Patients were enrolled if at least one culture grew positive with Cryptococcus neoformans. Control of sterilization was warranted 2 weeks (Wk2) and 3 months (Mo3) after antifungal therapy onset. 208 HIV-positive or -negative adult patients were analyzed. Treatment failure (death or mycological failure) at Wk2 and Mo3 was the main outcome measured. Combination of amphotericin B+flucytosine (AMB+5FC) was the best regimen for induction therapy in patients with meningoencephalitis and in all patients with high fungal burden and abnormal neurology. In those patients, treatment failure at Wk2 was 26% in the AMB+5FC group vs. 56% with any other treatments (p<0.001). In patients treated with AMB+5FC, factors independently associated with Wk2 mycological failure were high serum antigen titer (OR [95%CI] = 4.43[1.21–16.23], p = 0.025) and abnormal brain imaging (OR = 3.89[1.23–12.31], p = 0.021) at baseline. Haematological malignancy (OR = 4.02[1.32–12.25], p = 0.015), abnormal neurology at baseline (OR = 2.71[1.10–6.69], p = 0.030) and prescription of 5FC for less than 14 days (OR = 3.30[1.12–9.70], p = 0.030) were independently associated with treatment failure at Mo3. Conclusion/Significance Our results support the conclusion that induction therapy with AMB+5FC for at least 14 days should be prescribed rather than any other induction treatments in all patients with high fungal burden at baseline regardless of their HIV serostatus and of the presence of proven meningoencephalitis.
Troublesome Heterotopic Ossification after Central Nervous System Damage: A Survey of 570 Surgeries
Fran?ois Genêt,Claire Jourdan,Alexis Schnitzler,Christine Lautridou,Didier Guillemot,Thierry Judet,Serge Poiraudeau,Philippe Denormandie
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016632
Abstract: Heterotopic ossification (HO) is a frequent complication after central nervous system (CNS) damage but has seldom been studied. We aimed to investigate features of HO for the first time in a large sample and the rate of early recurrence of HO in terms of the time of surgery.
Antibiotic Innovation May Contribute to Slowing the Dissemination of Multiresistant Streptococcus pneumoniae: The Example of Ketolides
Lulla Opatowski, Laura Temime, Emmanuelle Varon, Roland Leclerc, Henri Drugeon, Pierre-Yves Bo?lle, Didier Guillemot
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002089
Abstract: Background Despite increasingly frequent bacterial resistance to antibiotics, antibacterial innovation is rare. Ketolides constitute one of the very few new antibiotic classes active against Streptococcus pneumoniae developed during the last 25 years. Their mechanism of action resembles that of macrolides, but they are unaffected by common resistance mechanisms. However, cross-resistance to ketolides has been observed in some macrolide-resistant strains. We examined how new antibiotic exposure may affect overall pneumococcal resistance patterns in the population. The aims of this study were to assess the potential dissemination of newly emerged resistances and to control the selection of strains already multiresistant to existing antimicrobials. Methodology/Principal Findings We developed an age-structured population model for S. pneumoniae transmission in a human community exposed to heptavalent vaccine, and β-lactams, macrolides and ketolides. The dynamics of intra-individual selection of resistant strains under antibiotic exposure and interindividual transmission were simulated, with antibiotic-specific resistance mechanisms defining the path to co-resistances and cross-resistances, and parameters concerning the French situation. Results of this simulation study suggest that new antibiotic consumption could markedly slow the diffusion of multiresistant strains. Wider use was associated with slower progression of multiresistance. When ketolides were prescribed to all ages, resistance to them reached 10% after >15 years, while it took >40 years when they were prescribed only to adults. In the scenario according to which new antibiotics totally replaced former antimicrobials, the β-lactam resistance rate was limited at 70%. Conclusions In a context of widespread vaccination and rational use of antibiotics, innovative antibiotic, prescribed to all age groups, may have an added impact on multiresistant-strain dissemination in the population.
S. pneumoniae transmission according to inclusion in conjugate vaccines: Bayesian analysis of a longitudinal follow-up in schools
Simon Cauchemez, Laura Temime, Alain-Jacques Valleron, Emmanuelle Varon, Guy Thomas, Didier Guillemot, Pierre-Yves Bo?lle
BMC Infectious Diseases , 2006, DOI: 10.1186/1471-2334-6-14
Abstract: Here, some of these characteristics were estimated for vaccine and non-vaccine serotypes from the follow-up of 4,488 schoolchildren in France in 2000. A Bayesian approach using Markov chain Monte Carlo data augmentation techniques was used for estimation.Vaccine and non-vaccine serotypes were found to have similar characteristics: the mean duration of carriage was 23 days (95% credible interval (CI): 21, 25 days) for vaccine serotypes and 22 days (95% CI: 20, 24 days) for non-vaccine serotypes; within a school of size 100, the Secondary Attack Rate was 1.1% (95% CI: 1.0%, 1.2%) for both vaccine and non-vaccine serotypes.This study supports that, in 3–6 years old children, no competitive advantage exists for vaccine serotypes compared to non-vaccine serotypes. This is an argument in favour of important serotype replacement. It would be important to validate the result for infants, who are known to be the main reservoir in maintaining transmission. Overall reduction in pathogenicity should also be taken into account in forecasting the future burden of pneumococcal colonization in vaccinated populations.Less than 10 Streptococcus pneumoniae (S. pneumoniae) serotypes, among more than 90, have been included in the S. pneumoniae conjugate vaccine formulation. Since these serotypes account for a large part of carriage (almost 80% of all carriage in the United States [1]) and the vaccine protects against colonization [2], a reduction in overall carriage after vaccination is expected, and has indeed been observed in vaccinated populations [3]. However, recent trends of pneumococcal colonization in the United States, following the introduction of conjugate vaccination, indicate serotype replacement [4,5], whereby a decrease in vaccine serotypes carriage is followed by an increase in carriage of non-vaccine serotypes. The eventual extent of this replacement is as yet unknown.Mathematical models have predicted that replacement could occur in case of direct competition between s
Des mégapoles mises en carte.
Luc Guillemot
EspacesTemps.net , 2009,
Abstract: La nouvelle collection Atlas Mégapoles des éditions Autrement , dirigée par Thierry Sanjuan, a pour ambition de donner à voir l’espace des mégapoles à travers une cinquantaine de cartes, un reportage photographique et des graphiques. Les deux premières parutions sont consacrées à New York, la mégapole occidentale par excellence, et à Shangha , son pendant asiatique. D’emblée, on se demande ce qui est entendu par mégapole , et la deuxième de couverture répond ...
Detections of millisecond pulsars with the Fermi Large Area Telescope
Lucas Guillemot
Physics , 2009,
Abstract: The Fermi observatory was launched on June 11, 2008. It hosts the \emph{Large Area Telescope} (LAT), sensitive to $\gamma$-ray photons from 20 MeV to over 300 GeV. When the LAT began its activity, nine young and energetic pulsars were known in $\gamma$ rays. At least several tens of pulsar detections by the LAT were predicted before launch. The LAT also allowed the study of millisecond pulsars (MSPs), never firmly detected in $\gamma$ rays before Fermi. This thesis first presents the pulsar timing campaign for the LAT, in collaboration with large radiotelescopes and X-ray telescopes, allowing for high sensitivity pulsed searches. Furthermore, it lead to quasi-homogeneous coverage of the galactic MSPs, so that the search for pulsations in LAT data for this population of stars was not affected by an \emph{a priori} bias. We present a search for pulsations from these objects in LAT data. For the first time, eight galactic MSPs have been detected as sources of pulsed $\gamma$-ray emission over 100 MeV. In addition, a couple of good candidates for future detection are seen. A similar search for globular cluster MSPs has not succeeded so far. Comparison of the phase-aligned $\gamma$-ray and radio light curves, as well as the spectral shapes, leads to the conclusion that their $\gamma$-ray emission is similar to that of normal pulsars, and is probably produced in the outer-magnetosphere. This discovery suggests that many unresolved $\gamma$-ray sources are unknown MSPs.
Imported Episodic Rabies Increases Patient Demand for and Physician Delivery of Antirabies Prophylaxis
Zélie Lardon,Laurence Watier,Audrey Brunet,Claire Bernède,Maryvonne Goudal,Laurent Dacheux,Yolande Rotivel,Didier Guillemot equal contributor,Hervé Bourhy equal contributor
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000723
Abstract: Background Imported cases threaten rabies reemergence in rabies-free areas. During 2000–2005, five dog and one human rabies cases were imported into France, a rabies-free country since 2001. The Summer 2004 event led to unprecedented media warnings by the French Public Health Director. We investigated medical practice evolution following the official elimination of rabies in 2001; impact of subsequent episodic rabies importations and national newspaper coverage on demand for and delivery of antirabies prophylaxis; regular transmission of epidemiological developments within the French Antirabies Medical Center (ARMC) network; and ARMC discussions on indications of rabies post-exposure prophylaxis (RPEP). Methodology/Principal Findings Annual data collected by the National Reference Center for Rabies NRCR (1989–2006) and the exhaustive database (2000–2005) of 56 ARMC were analyzed. Weekly numbers of patients consulting at ARMC and their RPEP- and antirabies-immunoglobulin (ARIG) prescription rates were determined. Autoregressive integrated moving-average modeling and regression with autocorrelated errors were applied to examine how 2000–2005 episodic rabies events and their related national newspaper coverage affected demand for and delivery of RPEP. A slight, continuous decline of rabies-dedicated public health facility attendance was observed from 2000 to 2004. Then, during the Summer 2004 event, patient consultations and RPEP and ARIG prescriptions increased by 84%, 19.7% and 43.4%, respectively. Moreover, elevated medical resource use persisted in 2005, despite communication efforts, without any secondary human or animal case. Conclusions Our findings demonstrated appropriate responsiveness to reemerging rabies cases and effective newspaper reporting, as no secondary case occurred. However, the ensuing demand on medical resources had immediate and long-lasting effects on rabies-related public health resources and expenses. Henceforth, when facing such an event, decision-makers must anticipate the broad impact of their media communications to counter the emerging risk on maintaining an optimal public health organization and implement a post-crisis communication strategy.
Significant Reduction of Antibiotic Use in the Community after a Nationwide Campaign in France, 2002–2007
Elifsu Sabuncu,Julie David,Claire Bernède-Bauduin,Sophie Pépin,Michel Leroy,Pierre-Yves Bo?lle,Laurence Watier,Didier Guillemot
PLOS Medicine , 2009, DOI: 10.1371/journal.pmed.1000084
Abstract: Background Overuse of antibiotics is the main force driving the emergence and dissemination of bacterial resistance in the community. France consumes more antibiotics and has the highest rate of beta-lactam resistance in Streptococcus pneumoniae than any other European country. In 2001, the government initiated “Keep Antibiotics Working”; the program's main component was a campaign entitled “Les antibiotiques c'est pas automatique” (“Antibiotics are not automatic”) launched in 2002. We report the evaluation of this campaign by analyzing the evolution of outpatient antibiotic use in France 2000–2007, according to therapeutic class and geographic and age-group patterns. Methods and Findings This evaluation is based on 2000–2007 data, including 453,407,458 individual reimbursement data records and incidence of flu-like syndromes (FLSs). Data were obtained from the computerized French National Health Insurance database and provided by the French Sentinel Network. As compared to the preintervention period (2000–2002), the total number of antibiotic prescriptions per 100 inhabitants, adjusted for FLS frequency during the winter season, changed by ?26.5% (95% confidence interval [CI] ?33.5% to ?19.6%) over 5 years. The decline occurred in all 22 regions of France and affected all antibiotic therapeutic classes except quinolones. The greatest decrease, ?35.8% (95% CI ?48.3% to ?23.2%), was observed among young children aged 6–15 years. A significant change of ?45% in the relationship between the incidence of flu-like syndromes and antibiotic prescriptions was observed. Conclusions The French national campaign was associated with a marked reduction of unnecessary antibiotic prescriptions, particularly in children. This study provides a useful method for assessing public-health strategies designed to reduce antibiotic use.
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