Rapid polymyxin NP test for the detection of polymyxin resistance mediated by the MCR-1/MCR-2 genes

The Rapid Polymyxin NP test has been recently developed to rapidly detect polymyxin resistance in Enterobacteriaceae. Here we evaluated this test for detecting MCR- 1/MCR-2-producing Enterobacteriaceae using a collection of 70 non-redundant strains either recovered from the environment, animals, or humans. Sensitivity and specificity were found to be 100%

Acquisition of broad-spectrum cephalosporin resistance leading to colistin resistance in Klebsiella pneumoniae

An extended-spectrum β-lactamase (ESBL)-producing and colistin-resistant Klebsiella pneumoniae clinical isolate was recovered from a patient who was treated with cefotaxime. This isolate harbored a blaCTX-M-15 ESBL gene that was associated with an ISEcp1 insertion sequence. Transposition of that tandem occurred within the chromosomal mgrB gene, leading to inactivation of the mgrB gene and consequently to acquired resistance to colistin. We showed here a coselection of colistin resistance as a result of a broad- spectrum cephalosporin selective pressure

Interactions of Aspergillus fumigatus and Stenotrophomonas maltophilia in an in vitro Mixed Biofilm Model: Does the Strain Matter?

Introduction:Aspergillus fumigatus (Af) and Stenotrophomonas maltophilia (Sm) are pathogenic microorganisms, which coexist in the respiratory tract of cystic fibrosis (CF) patients. We recently developed an in vitro model of mixed biofilm associating Af ATCC 13073-GFP (Af13073) and Sm ATCC 13637 (Sm13637) and described an antibiosis effect. The present study aim was to assess the antibiosis of Sm on Af using different strains and to analyze the potential synergistic virulence of these strains in an in vivo Galleria mellonella model.Methods: The effect of Sm13637 was evaluated on eight Af strains and the effect of nine Sm strains was evaluated on Af13073. The strains originated from clinical cases (human and animal) and from environment. Fungal and bacterial inocula were simultaneously inoculated to initiate mixed biofilm formation. Fungal growth inhibition was analyzed by qPCR and CLSM and the fungal cell wall modifications by TEM analysis. The virulence of different Sm strains was assessed in association with Af in G. mellonella larvae.Results: All strains of Af and Sm were able to produce single and mixed biofilms. The antibiosis effect of Sm13637 was similar whatever the Af strain tested. On the other hand, the antibiosis effect of Sm strains was bacterial-fitness and strain dependent. One strain (1/9) originated from animal clinical case was never able to induce an antibiosis, even with high bacterial concentration. In the G. mellonella model, co-inoculation with Sm13637 and Af13073 showed synergism since the mortality was 50%, i.e., more than the summed virulence of both.Conclusion: Human clinical strains of Sm yielded in higher antibiosis effect on Af and in a thinner mixed biofilm, probably due to an adaptive effect of these strains. Further research covering Af increased wall thickness in the presence of Sm strains, and its correlation with modified antifungal susceptibility is encouraged in patients with chronic respiratory infections by these 2 microorganisms

Are animals a source of Stenotrophomonas maltophilia in human infections? Contributions of a nationwide molecular study

Stenotrophomonas maltophilia (Sm) is an archetypal environmental opportunistic bacterium responsible for health care-associated infections. The role of animals in human Sm infections is unknown. This study aims to reveal the genetic and phylogenetic relationships between pathogenic strains of Sm, both animal and human, and identify a putative role for animals as a reservoir in human infection. We phenotypically and genotypically characterized 61 Sm strains responsible for animal infections (mainly respiratory tract infections in horses) from a French nationwide veterinary laboratory network. We tested antimicrobial susceptibility and performed MLST and genogrouping using the concatenation of the seven housekeeping genes from the original MLST scheme. Excluding the eight untypeable strains owing to the lack of gene amplification, only 10 out of the 53 strains yielded a known ST (ST5, ST39, ST162, ST8, ST27, ST126, ST131). The genogroup distribution highlighted not only genogroups (genogroups 5 and 9) comprised exclusively of animal strains but also genogroups shared by human and animal strains. Interestingly, these shared genogroups were primarily groups 2 and 6, which have previously been identified as the two most frequent genogroups among human-pathogenic Sm strains, especially among respiratory pathogens. The antimicrobial susceptibility testing underlined the presence of acquired resistance: 18.8 and 7.5% of the tested isolates were resistant to the sulfonamide-trimethoprim combination and ciprofloxacin, respectively. Animal strains of Sm shared phylogenetic traits with some of the most successful human strains. The exact relationships between the human and animal strains, and the genetic support of these common traits, need to be determined

Colistin resistance in Parisian inpatient faecal Escherichia coli as the result of two distinct evolutionary pathways

Beyond plasmid-encoded resistance (mcr genes) prevalence in strain collections, large epidemiological studies to estimate the human burden of colistin-resistant Escherichia coli gut carriage are lacking.Objectives: To evaluate the prevalence of colistin-resistant E. coli carriage in inpatients and decipher the molecular support of resistance and the genetic background of the strains.Methods: During a 3 month period in 2017, we prospectively screened patients in six Parisian hospitals for rectal carriage of colistin-resistant E. coli using a selective medium, a biochemical confirmatory test and MIC determination. WGS of the resistant strains and their corresponding plasmids was performed.Results: Among the 1217 screened patients, 153 colistin-resistant E. coli strains were isolated from 152 patients (12.5%). The mcr- 1 gene was identified in only seven isolates (4.6%) on different plasmid scaffolds. The genetic background of these MCR-1 producers argued for an animal origin. Conversely, the remaining 146 colistin-resistant E. coli exhibited a phylogenetic distribution corresponding to human gut commensal/clinical population structure (B2 and D phylogroup predominance); 72.6% of those isolates harboured convergent mutations in the PmrA and PmrB proteins, constituting a two-component system shown to be associated with colistin resistance.Conclusions: We showed that the occurrence at a high rate of colistin resistance in human faecal E. coli is the result of two distinct evolutionary pathways, i.e. the occurrence of chromosomal mutations in an endogenous E. coli population and the rare acquisition of exogenous mcr-1- bearing strains probably of animal origin. The involved selective pressures need to be identified in order to develop preventative strategies

mcr-9, An inducible gene encoding an acquired phosphoethanolamine transferase in Escherichia coli, and its origin

The plasmid-located mcr-9 gene, encoding a putative phosphoethanolamine transferase, was identified in a colistin-resistant human fecal Escherichia coli strain belonging to a very rare phylogroup, the D-ST69-O15:H6 clone. This MCR-9 protein shares 33% to 65% identity with the other plasmid-encoded MCR-type enzymes identified (MCR-1 to -8) that have been found as sources of acquired resistance to polymyxins in Enterobacteriaceae. Analysis of the lipopolysaccharide of the MCR-9- producing isolate revealed a function similar to that of MCR-1 by adding a phosphoethanolamine group to lipid A and subsequently modifying the structure of the lipopolysaccharide. However, a minor impact on susceptibility to polymyxins was noticed once the mcr-9 gene was cloned and produced in an E. coli K-12-derived strain. Nevertheless, we showed here that subinhibitory concentrations of colistin induced the expression of the mcr-9 gene, leading to increased MIC levels. This inducible expression was mediated by a two-component regulatory system encoded by the qseC and qseB genes located downstream of mcr-9. Genetic analysis showed that the mcr-9 gene was carried by an IncHI2 plasmid. In silico analysis revealed that the plasmid-encoded MCR-9 shared significant amino acid identity (ca. 80%) with the chromosomally encoded MCR-like proteins from Buttiauxella spp. In particular, Buttiauxella gaviniae was found to harbor a gene encoding MCR-BG, sharing 84% identity with MCR-9. That gene was neither expressed nor inducible in its original host, which was fully susceptible to polymyxins. This work showed that mcr genes may circulate silently and remain undetected unless induced by colistin

Fine-Scale Structure Analysis Shows Epidemic Patterns of Clonal Complex 95, a Cosmopolitan Escherichia coli Lineage Responsible for Extraintestinal Infection

The Escherichia coli lineage known as clonal complex 95 (CC95) is a cosmopolitan human-associated lineage responsible for a significant fraction of extraintestinal infections of humans. Whole-genome sequence data of 200 CC95 strains from various origins enabled determination of the CC95 pangenome. The pangenome analysis revealed that strains of the complex could be assigned to one of five subgroups that vary in their serotype, extraintestinal virulence, virulence gene content, and antibiotic resistance gene profile. A total of 511 CC95 strains isolated from humans living in France, Australia, and the United States were screened for their subgroup membership using a PCR-based method. The CC95 subgroups are nonrandomly distributed with respect to their geographic origin. The relative frequency of the subgroups was shown to change through time, although the nature of the changes varies with continent. Strains of the subgroups are also nonrandomly distributed with respect to source of isolation (blood, urine, or feces) and host sex. Collectively, the evidence indicates that although strains belonging to CC95 may be cosmopolitan, human movement patterns have been insufficient to homogenize the distribution of the CC95 subgroups. Rather, the manner in which CC95 strains evolve appears to vary both spatially and temporally. Although CC95 strains appeared globally as pandemic, fine-scale structure analysis shows epidemic patterns of the CC95 subgroups. Furthermore, the observation that the relative frequency of CC95 subgroups at a single locality has changed over time indicates that the relative fitness of the subgroups has changedThis material is based in part on work supported by Office of Research and Development, Medical Research Service, Department of Veterans Affairs (grant 1 I01 CX000920-01 to J.R.J.). This work was partially supported by a grant from the Fondation Pour la Recherche Médicale (Équipe FRM 2016, DEQ20161136698) to E.D

Caractérisation phénotypique et génotypique des staphylocoques à coagulase négative responsables de bactériémies associées aux soins en réanimation néonatale

Les bactériémies liées aux cathéters centraux (BLC) représentent la première cause d infection associée aux soins chez les nouveau-nés grands prématurés ; les staphylocoques à coagulase négative (SCN) sont les principales bactéries responsables. Nous avons caractérisé 50 SCN isolés de BLC chez 46 grands prématurés hospitalisés en réanimation néonatale (RNN) à l hôpital Béclère : sensibilité aux antibiotiques, présence de marqueur de virulence .Nous avons également évalué la sensibilité à 3 antiseptiques et à la mupirocine, antibiotique local très utilisé dans ce service, ainsi que la présence des gènes de résistance qacA/B et mupA. Les SCN sont caractérisés (i) par un haut niveau de résistance aux antibiotiques et aux antiseptiques, (ii) une forte prévalence des gènes impliqués dans la virulence et dans la résistance (IS256, ica ADBC, mupA, qacA/B). L adaptation de ces souches à l environnement de la RNN en terme de pression de sélection a probablement permis leur succès épidémique.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Détermination de la sensibilité aux antibiotiques d'Helicobacter pylori (validation d'un algorithme associant HelicoDR® et antibiogramme par Etest®)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Epidémiologie moléculaire et sensibilité aux antibiotiques des souches invasives de Streptococcus pneumoniae

Streptococcus pneumoniae (pneumocoque) est un des principaux pathogènes responsables de pathologies communautaires. A partir de plusieurs échantillons d'origine régionale et nationale représentant au total plus de 650 souches invasives (hémocultures, LCR), ce travail s'est attaché à étudier: la place du pneumocoque au sein des germes sérogroupes et sérotypes identifiés chez l'enfant et l'adulte, l'épidémiologie moléculaire des souches rencontrées au sein de ces deux populations, leur sensibilité aux antibiotiques (CMI, tolérance), le support génétique de la résistance aux macrolides et aux fluoroquinolones, la prévalence de la résistance de bas niveau aux fluoroquinoloques par la mise au point d'une technique spécifique de PCR en temps réel.Streptococcus pneumoniae (pneumococcus) is one of the main pathogens implicated in community acquired infectious diseases. Using differents samples of strains collected at a regional or national level (total: 650 invasive strains isolated from blood or cerebrospinal fluid), we evaluated: the role of pneumococcus in bloodstream infection identified in hospitals, the distribution of serotypes and serogroups in children and adults, the molecular epidemiology of the strains in these two populations, their antibiotic susceptibilities (MIC, penicillin and vancomycine tolerance), the genetic support of macrolides and fluoroquinolones resistance, the prevalence of low level fluoroquinolones resistance (first step ParC mutant) using a new real time PCR protocol.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF