R Leclercq

Université de Caen Basse-Normandie, Caen, Lower Normandy, France

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Publications (254)921.56 Total impact

  • M. Auzou · J. Caillon · C. Poyart · P. Weber · M.-C. Ploy · R. Leclercq · V. Cattoir
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    ABSTRACT: The primary objective of our study was to obtain susceptibility data for josamycin against Streptococcus pyogenes isolated from patients presenting with upper respiratory tract infections in France. The secondary objective was to characterize the molecular mechanism of resistance in macrolide-resistant isolates. MICs of erythromycin, clarithromycin, azithromycin, josamycin, and clindamycin were determined by the broth microdilution method. Resistance genes erm(B), erm(TR), and mef(A) were screened by PCR. The MIC50 and MIC90 of josamycin against 193 isolates of S. pyogenes were 0.12 and 0.25mg/L, respectively, with a resistance rate estimated at 4.7%. Resistance was due to the erm(B) gene whereas strains harboring erm(TR) or mef(A) remained susceptible. Josamycin was active against >95% of S. pyogenes isolated from patients with upper respiratory tract infections, and can be used as an alternative for the treatment of pharyngitis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    No preview · Article · Jun 2015 · Médecine et Maladies Infectieuses

  • No preview · Book · Jan 2015
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    ABSTRACT: Detection of microorganisms by blood cultures (BCs) is essential in managing patients with bacteraemia. Rather than the number of punctures, the volume of blood drawn is considered paramount in efficient and reliable detection of microorganisms. We performed a one-year prospective multicentre study in adult emergency departments of three French university hospitals comparing two methods for BCs: a unique blood culture (UBC) collecting a large volume of blood (40 ml) and the standard method of multiple blood cultures (MBC). The performances of both methods for bacterial contamination and efficient microbial detection were compared, each patient serving as his own control. Amongst the 2,314 patients included, three hundred were positive for pathogens (n=245) or contaminants (n=55). Out of the 245 patients, 11 were positive for pathogens by UBC but negative by MBC and 7 negative by UBC but positive by MBC (P=0.480). In the subgroup of 137 patients with only two BCs, UBC was superior to MBC (P=0.044). Seven and 17 patients had contaminated BCs by UBC and MBC only, respectively (P=0.062). Considering the sums of pathogens missed and contaminants, UBC significantly outperformed MBC (P=0.043). Considering the complete picture of cost savings, efficient detection of microorganisms and decrease in contaminations, UBC offers an interesting alternative to MBC.This article is protected by copyright. All rights reserved.
    Full-text · Article · Apr 2014 · Clinical Microbiology and Infection
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    ABSTRACT: One of the major challenges for the next decades will be the assessment of how ecosystem changes could affect human health. The microbiological vulnerability and the resilience of the aquatic environment to contamination by fecal germs, which in industrialized countries is accompanied by pharmaceutical contamination, will be a major health concern. Bacterial resistance to antibiotics is a complex ecological phenomenon which should be investigated, by considering the circulation of micro-organisms and the corresponding resistance genes within the four major ecosystems: humans, animals, soil and water. In the decades to come, estuaries will be exposed to a great chemical and microbial contamination, in correlation to the increase of the demography and human activity on their watershed. The study carried out in the Seine Estuary, and at the small-scale of a hospital- WWTP-river continuum, shows the vulnerability, but also the resilience, of this environment, to the contamination by antibiotics and antibiotic-resistant bacteria.
    No preview · Article · Jan 2014
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    ABSTRACT: An important question regarding the biologic implications of antibiotic-resistant microbes is how resistance impacts the organism's overall fitness and virulence. Currently it is generally thought that antibiotic resistance carries a fitness cost and reduces virulence. For the human pathogen Pseudomonas aeruginosa, treatment with carbapenem antibiotics is a mainstay of therapy that can lead to the emergence of resistance, often through the loss of the carbapenem entry channel OprD. Transposon insertion-site sequencing was used to analyze the fitness of 300,000 mutants of P. aeruginosa strain PA14 in a mouse model for gut colonization and systemic dissemination after induction of neutropenia. Transposon insertions in the oprD gene led not only to carbapenem resistance but also to a dramatic increase in mucosal colonization and dissemination to the spleen. These findings were confirmed in vivo with different oprD mutants of PA14 as well as with related pairs of carbapenem-susceptible and -resistant clinical isolates. Compared with OprD(+) strains, those lacking OprD were more resistant to killing by acidic pH or normal human serum and had increased cytotoxicity against murine macrophages. RNA-sequencing analysis revealed that an oprD mutant showed dramatic changes in the transcription of genes that may contribute to the various phenotypic changes observed. The association between carbapenem resistance and enhanced survival of P. aeruginosa in infected murine hosts suggests that either drug resistance or host colonization can cause the emergence of more pathogenic, drug-resistant P. aeruginosa clones in a single genetic event.
    Full-text · Article · Nov 2013 · Proceedings of the National Academy of Sciences
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    ABSTRACT: To report an outbreak due to an unusual strain of Enterococcus faecium containing both the vanA and vanB genes, in France, where the rate of glycopeptide-resistant enterococci (GRE) is below 1%. Cases were patients infected or colonized with GRE on the haematology ward. Contact patients were screened by real-time PCR performed on rectal swabs. Clinical features were compared for GRE-positive and GRE-negative patients. GRE isolates were characterized by phenotypic and molecular methods including PFGE. Conjugation experiments were performed to identify van genetic support. After the index patient presented a bacteraemia with vanA/vanB E. faecium, 56 contact patients were screened, 7 of whom were found to be GRE positive: 6 additional cases with vanA/vanB E. faecium and 1 with GRE carrying vanA only. PFGE confirmed the clonal relationship of the seven vanA/vanB E. faecium strains, whereas the vanA isolate was distinct. Only the vanA gene could be transferred to enterococcal recipients by conjugation, and it was probably localized on a mobile genetic element. All isolates were resistant to vancomycin (MIC > 256 mg/L) and teicoplanin (MIC = 24-32 mg/L), but were susceptible to tigecycline (MIC = 0.09 mg/L), linezolid (MIC = 0.75 mg/L) and daptomycin (MIC = 1-2 mg/L). Significant differences (P < 0.001) between carriers and non-carriers of GRE were observed for the median duration of hospitalization (57 days versus 16.5 days) and of neutropenia (40 days versus 6 days), the median number of antibiotics used (5 versus 1.5) and the duration of glycopeptide treatment (14.5 days versus 0 days). vanA/vanB E. faecium strains, although rare, can emerge in the absence of previous outbreaks of vanA-GRE or vanB-GRE.
    Full-text · Article · Oct 2013 · Journal of Antimicrobial Chemotherapy
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    ABSTRACT: Objectives: To investigate the resistance mechanisms of β-lactam-resistant Pseudomonas aeruginosa isolated from cystic fibrosis (CF) patients in France. Methods: Two-hundred-and-four P. aeruginosa CF isolates were collected in 10 French university hospitals in 2007. Their susceptibility to 14 antibiotics and their resistance mechanisms to β-lactams were investigated. Their β-lactamase contents were characterized by isoelectric focusing, PCR and enzymatic assays. Expression levels of efflux pumps and the intrinsic β-lactamase AmpC were quantified by reverse transcription real-time quantitative PCR. Genotyping was performed using multiple-locus variable number of tandem repeats analysis (MLVA). The oprD genes were sequenced and compared with those of reference P. aeruginosa strains. To assess deficient OprD production, western blotting experiments were carried out on outer membrane preparations. Results: MLVA typing discriminated 131 genotypes and 47 clusters. One-hundred-and-twenty-four isolates (60.8%) displayed a susceptible phenotype to β-lactams according to EUCAST breakpoints. In the 80 remaining isolates, resistance to β-lactams resulted from derepression of intrinsic cephalosporinase AmpC (61.3%) and/or acquisition of secondary β-lactamases (13.8%). Efflux pumps were up-regulated in 88.8% of isolates and porin OprD was lost in 53.8% of isolates due to frameshifting or nonsense mutations in the oprD gene. Conclusions: β-Lactam resistance rates are quite high in CF strains of P. aeruginosa isolated in France and not really different from those reported for nosocomial strains. Development of β-lactam resistance is correlated with patient age. It results from intrinsic mechanisms sequentially accumulated by bacteria isolated from patients who have undergone repeated courses of chemotherapy. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
    Full-text · Article · Aug 2013 · Journal of Antimicrobial Chemotherapy
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    ABSTRACT: Objectives Mupirocin is the cornerstone of decolonization regimens, a successful strategy to prevent healthcare-associated staphylococcal infections. Several recent studies have reported alarming results: (i) an extending reservoir of mupA, the ancestral mobile resistance gene, among coagulase-negative staphylococci (CoNS); (ii) the emergence of a new resistance gene (mupB); and (iii) a growing number of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MRSA), including highly pathogenic clones. We performed a nationwide prospective study in France to detect such trends among invasive staphylococci.
    Full-text · Article · Aug 2013 · Journal of Antimicrobial Chemotherapy
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    ABSTRACT: As opposed to Enterococcus faecalis, which is intrinsically resistant to lincosamides, streptogramins A, and pleuromutilins (LSAP phenotype) by production of the ABC protein Lsa(A), Enterococcus faecium is naturally susceptible. Since this phenotype may be selected for in vivo by quinupristin-dalfopristin (Q-D), the aim of this study was to investigate the molecular mechanism of acquired LSAP resistance in E. faecium. Six LSAP-resistant in vitro mutants of E. faecium HM1070 as well as three different pairs of clinical isolates (pre- and postexposure to Q-D) were studied. The full genome sequence of an in vitro mutant (E. faecium UCN90B) was determined by using 454 sequencing technology and was compared with that of the parental strain. Single-nucleotide replacement was carried out to confirm the role of this mutation. By comparative genomic analysis, a point mutation was found within a 1,503-bp gene coding for an ABC homologue showing 66% amino acid identity with Lsa(A). This mutation (C1349T) led to an amino acid substitution (Thr450Ile). An identical mutation was identified in all in vitro and in vivo resistant strains but was not present in susceptible strains. The wild-type allele was named eat(A) (for Enterococcus ABC transporter), and its mutated allelic variant was named eat(A)v. The introduction of eat(A)v from UCN90B into HM1070 conferred the LSAP phenotype, whereas that of eat(A) from HM1070 into UCN90B restored susceptibility entirely. This is the first description of the molecular mechanism of acquired LSAP resistance in E. faecium. Characterization of the biochemical mechanism of resistance and the physiological role of this ABC protein need further investigations.
    Preview · Article · Jul 2013 · Antimicrobial Agents and Chemotherapy
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    ABSTRACT: Rhodococcus equi, the causal agent of rhodococcosis, is a major pathogen of foals and is also responsible for severe infections in immunocompromised humans. Of great concern, strains resistant to currently used antibiotics have emerged. As the number of drugs that are efficient in vivo is limited because of the intracellular localization of the bacterium inside macrophages, new active but cell-permeant drugs will be needed in the near future. In the present study, we evaluated, by in vitro and ex vivo experiments, the ability of the alpha-helical equine antimicrobial peptide eCATH1 to kill intracellular bacterial cells. Moreover, the therapeutic potential of the peptide was assessed in experimental rhodococcosis induced in mice, while the in vivo toxicity was evaluated by behavioral and histopathological analysis. The study revealed that eCATH1 significantly reduced the number of bacteria inside macrophages. Furthermore, the bactericidal potential of the peptide was maintained in vivo at doses that appeared to have no visible deleterious effects for the mice even after 7 days of treatment. Indeed, daily subcutaneous injections of 1 mg/kg body weight of eCATH1 led to a significant reduction of the bacterial load in organs comparable to that obtained after treatment with 10 mg/kg body weight of rifampin. Interestingly, the combination of the peptide with rifampin showed a synergistic interaction in both ex vivo and in vivo experiments. These results emphasize the therapeutic potential that eCATH1 represents in the treatment of rhodococcosis.
    Full-text · Article · Jul 2013 · Antimicrobial Agents and Chemotherapy
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    ABSTRACT: Unique resistance to lincosamides (L phenotype) due to the production of nucleotidyltransferases (Lnu) is uncommon among Gram-positive bacteria. The aim of the study was to characterize the L phenotype in a clinical isolate of the Streptococcus milleri group. The strain UCN93 was recovered from neonatal specimens and from the mother's vaginal swab. Identification was confirmed by sequencing of the sodA gene. Antimicrobial susceptibility testing was carried out by the disc diffusion method, while MICs were determined using the agar dilution method. Screening for lnu(A), lnu(B), lnu(C) and lnu(D) genes was performed by PCR. Genetic environment and support were determined by thermal asymmetric interlaced PCR and PCR mapping. The transfer of lincomycin resistance was also attempted by conjugation. UCN93 was unambiguously identified as Streptococcus anginosus. It was susceptible to all tested antibiotics, except lincomycin (MIC, 8 mg/L) and tetracycline (2 mg/L). The lnu(C) gene was found to be responsible for the L phenotype. It was shown that lnu(C) was associated with a gene coding for a transposase within a structure similar to the transposon MTnSag1, described once in Streptococcus agalactiae. Since MTnSag1 was found to be mobilized by Tn916 and S. anginosus UCN93 harboured a Tn916 transposon, several attempts at transfer were performed but they all failed. The lnu(C)-containing genetic element was inserted into a chromosomal intergenic sequence of S. anginosus. Since lnu(C) has been detected in only one S. agalactiae clinical isolate so far, this is its second description among clinically relevant streptococci.
    Preview · Article · Jun 2013 · Journal of Antimicrobial Chemotherapy
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    ABSTRACT: To determine if hospital effluent input has an ecological impact on downstream aquatic environment, antibiotic resistance in Enterococcus spp. along a medical center-retirement home-wastewater treatment plant-river continuum in France was determined using a culture-based method. Data on antibiotic consumption among hospitalized and general populations and levels of water contamination by antibiotics were collected. All isolated enterococci were genotypically identified to the species level, tested for in vitro antibiotic susceptibility, and typed by multilocus sequence typing. The erm(B) and mef(A) (macrolide resistance) and tet(M) (tetracycline resistance) genes were detected by PCR. Along the continuum, from 89 to 98% of enterococci, according to the sampled site, were identified as Enterococcus faecium. All E. faecium isolates from hospital and retirement home effluents were multiply resistant to antibiotics, contained erm(B) and mef(A) genes, and belonged to hospital-adapted clonal complex 17 (CC17). Even though this species remained dominant in the downstream continuum, the relative proportion of CC17 isolates progressively decreased in favor of other subpopulations of E. faecium that were more diverse, less resistant to antibiotics, and devoid of the classical macrolide resistance genes and that belonged to various sequence types. Antibiotic concentrations in waters were far below the MICs for susceptible isolates. CC17 E. faecium was probably selected in the gastrointestinal tract of patients under the pressure of administered antibiotics and then excreted together with the resistance genes in waters to progressively decrease along the continuum.
    Full-text · Article · Feb 2013 · Applied and Environmental Microbiology

  • No preview · Article · Jan 2013 · Revue des Maladies Respiratoires

  • No preview · Article · Jan 2013 · Revue des Maladies Respiratoires
  • V. Cattoir · R. Leclercq
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    ABSTRACT: La surveillance de l’évolution des résistances bactériennes aux antibiotiques a un double objectif. Elle est d’abord indispensable pour disposer de données guidant les protocoles de traitement probabiliste des infections. Ensuite, elle s’intègre dans la politique globale de prévention des infections nosocomiales. C’est un composant incontournable des indicateurs d’activité et de qualité des services de réanimation et des référentiels d’accréditation des établissements.
    No preview · Chapter · Jan 2013
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    Vincent Cattoir · Roland Leclercq
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    ABSTRACT: Twenty-five years ago, isolation of vancomycin-resistant Enterococcus faecium (VREm) was reported both in the UK and in France. Since then, VREm has spread worldwide in hospitals. Hospital outbreaks appeared to be related to the evolution since the end of 1980s of a subpopulation of E. faecium highly resistant to ampicillin and fluoroquinolones (the so-called clonal complex CC17) that later acquired resistance to vancomycin. CC17 isolates are presumably better adapted than other E. faecium isolates to the constraints of the hospital environment and most contain mobile genetic elements, phage genes, genes encoding membrane proteins, regulatory genes, a putative pathogenicity island and megaplasmids. Colonization and persistence are major features of VREm. Inherent characteristics of E. faecium including a remarkable genome plasticity, in part due to acquisition of IS elements, in particular IS16, have facilitated niche adaptation of this distinct E. faecium subpopulation that is multiply resistant to antibiotics. Quinupristin/dalfopristin and linezolid are licensed for the treatment of VREm infections, with linezolid often used as a first-line treatment. However, the emergence of plasmid-mediated resistance to linezolid by production of a Cfr methyltransferase in Enterococcus faecalis is worrying. Daptomycin has not been extensively evaluated for the treatment of VREm infections and resistant mutants have been selected under daptomycin therapy. Although control of VRE is challenging, a laissez-faire policy would result in an increased number of infections and would create an irreversible situation. Although so far unsuccessful, dissemination of glycopeptide-resistant Staphylococcus aureus with van genes acquired from resistant enterococci cannot be ruled out.
    Preview · Article · Dec 2012 · Journal of Antimicrobial Chemotherapy

  • No preview · Article · Oct 2012 · Journal of Equine Veterinary Science
  • Roland Leclercq · Vincent Cattoir
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    ABSTRACT: Glycopeptides, vancomycin and teicoplanin, are used parenterally mostly in infections due to staphylococci and enterococci resistant to β-lactams or in case of intolerance to these antibiotics. Both glycopeptides should be tested since susceptibility testing results may be dissociated. Both staphylococci and enterococci have developed resistance to glycopeptides, the first ones by mutation and the latter (mostly the Enterococcus faecium species) by gene acquisition. The disc-diffusion method poorly suits to the test of glycopeptides against staphylococci but is better suited for enterococci only if agar plates are incubated for 24 h. Various criteria in the lecture of zone diameters inhibition are to be considered that may lead to suspect resistance. In this case, MICs should be determined to categorize the isolates. Some Staphylococcus aureus isolates susceptible to vancomycin may present resistant sub-populations (hetero-VISA). For enterococci, the acquired resistance to vancomycin (VanA ou VanB) in E. faecium and Enterococcus faecalis should be distinguished from the intrinsic resistance (VanC) or Enterococcus gallinarum and Enterococcus casseliflavus since only the first one is associated with outbreaks and should be notified to health authorities.
    No preview · Article · Sep 2012 · Revue Francophone des Laboratoires
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    ABSTRACT: The purpose of this retrospective study was to evaluate the pathogenic role of Corynebacterium species in lower respiratory tract infections as well as their routine laboratory investigation. From April 2007 to August 2009, 27 clinical isolates were significantly recovered from respiratory specimens of 27 different patients clinically suspected of having lower respiratory tract infections. The average age of patients was 65 years, while 22 (81%) patients presented at least 1 predisposing condition. Of the 27 patients, 15 (56%) were classified as infected according to Centers for Disease Control and Prevention/National Healthcare Safety Network criteria, with 93% of infections being hospital acquired. All isolates were accurately identified to the species level using molecular methods (i.e., 17 Corynebacterium pseudodiphtheriticum, 7 Corynebacterium striatum, and 3 Corynebacterium accolens), whereas phenotypic methods remained frequently unreliable for identifying C. striatum and C. accolens strains. All tested isolates were susceptible to amoxicillin, imipenem, vancomycin, linezolid, and tigecycline, whereas most of them were resistant to erythromycin.
    No preview · Article · Aug 2012 · Diagnostic microbiology and infectious disease
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    ABSTRACT: Oxidative stress serves as an important host/environmental signal that triggers a wide range of responses in microorganisms. Here, we identified an oxidative stress sensor and response regulator in the important multidrug-resistant nosocomial pathogen Enterococcus faecium belonging to the MarR family and called AsrR (antibiotic and stress response regulator). The AsrR regulator used cysteine oxidation to sense the hydrogen peroxide which results in its dissociation to promoter DNA. Transcriptome analysis showed that the AsrR regulon was composed of 181 genes, including representing functionally diverse groups involved in pathogenesis, antibiotic and antimicrobial peptide resistance, oxidative stress, and adaptive responses. Consistent with the upregulated expression of the pbp5 gene, encoding a low-affinity penicillin-binding protein, the asrR null mutant was found to be more resistant to β-lactam antibiotics. Deletion of asrR markedly decreased the bactericidal activity of ampicillin and vancomycin, which are both commonly used to treat infections due to enterococci, and also led to over-expression of two major adhesins, acm and ecbA, which resulted in enhanced in vitro adhesion to human intestinal cells. Additional pathogenic traits were also reinforced in the asrR null mutant including greater capacity than the parental strain to form biofilm in vitro and greater persistance in Galleria mellonella colonization and mouse systemic infection models. Despite overexpression of oxidative stress-response genes, deletion of asrR was associated with a decreased oxidative stress resistance in vitro, which correlated with a reduced resistance to phagocytic killing by murine macrophages. Interestingly, both strains showed similar amounts of intracellular reactive oxygen species. Finally, we observed a mutator phenotype and enhanced DNA transfer frequencies in the asrR deleted strain. These data indicate that AsrR plays a major role in antimicrobial resistance and adaptation for survival within the host, thereby contributes importantly to the opportunistic traits of E. faecium.
    Full-text · Article · Aug 2012 · PLoS Pathogens

Publication Stats

8k Citations
921.56 Total Impact Points

Institutions

  • 2006-2014
    • Université de Caen Basse-Normandie
      • UFR of Pharmaceutical sciences
      Caen, Lower Normandy, France
  • 2000-2013
    • Centre Hospitalier Universitaire de Caen
      • Unité Réanimation Médicale
      Caen, Lower Normandy, France
  • 2011
    • Centre Hospitalier Universitaire de Nancy
      Laxou, Lorraine, France
  • 1997-2008
    • French National Centre for Scientific Research
      • Institut de Chimie des Substances Naturelles
      Lutetia Parisorum, Île-de-France, France
    • Université Paris-Est Créteil Val de Marne - Université Paris 12
      Créteil, Île-de-France, France
  • 1991-2004
    • Institut Pasteur
      Lutetia Parisorum, Île-de-France, France
  • 2002
    • Centre Hospitalier Intercommunal Creteil
      Créteil, Île-de-France, France
  • 1989-2000
    • Hôpital Henri Mondor (Hôpitaux Universitaires Henri Mondor)
      • Service de Bactériologie - Virologie
      Créteil, Île-de-France, France
  • 1996
    • Institut Jules Bordet
      Bruxelles, Brussels Capital Region, Belgium