Evaluation of the MRSA/SA ELITe MGB Assay for the Detection of Staphylococcus aureus in Bone and Joint Infections.

Bone and joint infections represent a potentially devastating complication of prosthetic orthopedic joint replacement, thus requiring both rapid and appropriate antibiotic treatment. Staphylococcus aureus is one of the most common pathogens involved in this pathology. Being able to assert its presence is the first step of efficient patient management. This monocenter study evaluated the MRSA/SA ELITe MGB assay for the molecular detection of S. aureus and methicillin-resistant S. aureus (MRSA) in bone and joint biopsy specimens and synovial fluids. This test, together with conventional techniques, including standard cultures and the 16S rRNA amplification assay, was performed on 208 successive perioperative samples collected prospectively for 1 year obtained from 129 patients. Using conventional techniques, we detected a microbial pathogen in 76 samples from 58 patients, 40 of which were identified as S. aureus. The limit of detection (LOD) of the MRSA/SA ELITe MGB assay was experimentally determined for bone and joint biopsy specimens and synovial fluids using negative samples spiked with S. aureus ATCC 43300. The sensitivities of S. aureus detection with the MRSA/SA ELITe MGB assay were 82.5% (33/40 samples) and 97.5% (39/40 samples) using the manufacturer's LOD and an experimentally determined LOD, respectively. Interestingly, using the osteoarticular specific LOD, 15 additional samples were determined to be positive for S. aureus DNA with the MRSA/SA ELITe MGB assay; in all cases, these samples were obtained from patients considered to be infected with S. aureus according to their clinical and microbiological records. The results were available within 24 h, which could help to expedite therapeutic decisions.

Evolution of Structural and Electronic Properties of TiSe2 under High Pressure.

A pressure-induced structural phase transition and its intimate link with the superconducting transition was studied for the first time in TiSe2 up to 40 GPa at room temperature using X-ray diffraction, transport measurement, and first-principles calculations. We demonstrate the occurrence of a first-order structural phase transition at 4 GPa from the standard trigonal structure (S.G.P3̅m1) to another trigonal structure (S-G-P3̅c1). Additionally, at 16 GPa, the P3̅c1 phase spontaneously transforms into a monoclinic C2/m phase, and above 24 GPa, the C2/m phase returns to the initial P3̅m1 phase. Electrical transport results show that metallization occurs above 6 GPa. The charge density wave observed at ambient pressure is suppressed upon compression up to 2 GPa with the emergence of superconductivity at 2.5 GPa, with a critical temperature (Tc) of 2 K. A structural transition accompanies the emergence of superconductivity that persists up to 4 GPa. The results demonstrate that the pressure-induced phase transitions explored by the experiments along with the theoretical predictions may open the door to a new path for searching and controlling the phase diagrams of transition metal dichalcogenides.

Low-Temperature Heat Capacity Anomalies in Ordered and Disordered Phases of Normal and Deuterated Thiophene.

We measured the specific heat Cp of normal (C4H4S) and deuterated (C4D4S) thiophene in the temperature interval of 1 ≤ T, K ≤ 25. C4H4S exhibits a metastable phase II2 and a stable phase V, both with frozen orientational disorder (OD), whereas C4D4S exhibits a metastable phase II2, which is analogous to the OD phase II2 of C4H4S and a fully ordered stable phase V. Our measurements demonstrate the existence of a large bump in the heat capacity of both stable and metastable C4D4S and C4H4S phases at temperatures of ∼10 K, which significantly departs from the expected Debye temperature behavior of Cp ≈ T3. This case study demonstrates that the identified low-temperature Cp anomaly, typically referred to as a "Boson-peak" in the context of glassy crystals, is not exclusive of disordered materials.

Ceratopogonidae (Diptera) Communities in a Protected Area Threatened by Urbanization.

This study highlights the species diversity of Ceratopogonidae from the Paranaense forest and adjacent grassland in a protected natural area of Argentina, and emphasizes the importance of conserving the last remaining marginal forest area surrounded by a strong urbanization. A total 46 species belonging to 10 genera were recorded from these two habitats. Species diversity was higher in the grassland, while dominance was greater in the forest. Twelve species were abundant, while the rest were scarce or rare. The composition of the ceratopogonid community differs between habitats: 15 species were exclusive to the forest, 4 to the grasslands, and 27 used both habitats indistinctly. Differences between habitats were observed in the abundances of Alluaudomyia schnacki Spinelli, Atrichopogon albinensis Ingram and Macfie, and Forcipomyia rioplatensis Marino and Spinelli. The sex ratio of the most abundant species did not show a definite pattern in relation to the habitats, except for Culicoides caridei (Brèthes), in which females were dominant. Atrichopogon balseiroi Spinelli and Forcipomyia williamsi Marino & Spinelli have only been recorded in Buenos Aires Province and were found exclusively in the forest during this study.

Duration of rifampin therapy is a key determinant of improved outcomes in early-onset acute prosthetic joint infection due to Staphylococcus treated with a debridement, antibiotics and implant retention (DAIR): a retrospective multicenter study in France.

Introduction: In patients undergoing a « debridement, antibiotics, and implant retention ¼ (DAIR) procedure for acute staphylococcal prosthetic joint infection (PJI), post-operative treatment with rifampin has been associated with a higher probability of success.(1,2) However, it is not known whether it is the total dose, delay of introduction or length of therapy with rifampin that is most strongly associated with the observed improved outcomes. Methods: A multicentric, retrospective cohort study of patients with acute staphylococcal hip and knee PJI treated with DAIR between January 2011 and December 2016. Failure of the DAIR procedure was defined as persistent infection, need for another surgery or death. We fitted logistic and Cox regression multivariate models to identify predictors of DAIR failure. We compared Kaplan-Meier estimates of failure probability in different levels of the 3 variables of interest - total dose, delay of introduction or length of therapy with rifampin - with the log-rank test. Results: 79 patients included (median age 71 years [63.5-81]; 55 men [70%]), including 54 (68%) DAIR successes and 25 (32%) DAIR failures. Patients observed for a median of 435 days [IQR 107.5-834]. Median ASA score significantly lower in DAIR successes than in DAIR failures (2 vs. 3, respectively p = 0.011). Bacterial cultures revealed 65 (82.3%) S. aureus and 16 (20.3%) coagulase negative staphylococci, with 2 patients being infected simultaneously with S. aureus and CNS. Among S. aureus isolates, 7 (10.8%) resistant to methicillin; 2 (3.1 %) resistant to rifampin. Median duration of antimicrobial therapy was 85 days [IQR 28.5-97.8]. Fifty-eight patients (73.4%) received rifampin at a median dose of 14.6 mg/kg/day |IQR 13-16.7], started at a median delay of 8.5 days [IQR, 4-7.5] after debridement surgery. Twenty-one patients (26.6%) developed a drug-related adverse event, leading to rifampin interruption in 6 of them (7.6% of total cohort). Determinants of DAIR failure were rifampin use (HR 0.17, IC [0.06, 0.45], p-value <0.001), association of rifampin with a fluoroquinolone (HR 0.19, IC [0.07, 0.53], p-value = 0.002) and duration of rifampin therapy (HR 0.97, IC [0.95, 1], p-value = 0.022). We did not observe a significant difference between DAIR successes and failures in rifampin use, dose and delay of introduction. In a multivariate Cox model, only duration of rifampin therapy was significantly associated with DAIR failure. Kaplan Meier estimate of DAIR failure probability was significantly higher in patients receiving less than 14 days of rifampin in comparison with those receiving more than 14 days of rifampin (p = 0.0017). Conclusion: Duration of rifampin therapy is a key determinant of improved outcomes in early-onset acute prosthetic joint infection due to Staphylococcus treated with DAIR.

Acute kidney injury in infective endocarditis: A retrospective analysis.

BACKGROUND: Acute kidney injury (AKI) is associated with high case fatality in infective endocarditis (IE), but epidemiological data on the frequency of AKI during IE is scarce. We aimed to describe the frequency and risk factors for AKI during the course of IE using Kidney Disease: Improving Global Outcomes consensual criteria. METHODS: Using the French hospital discharge database (French acronym PMSI), we retrospectively reviewed the charts of 112 patients presenting with a first episode of probable or definite IE between January 2010 and May 2015. RESULTS: Seventy-seven patients (68.8%) developed AKI. In univariate analysis, risk factors for AKI were cardiac surgery for IE (n=29, 37.7% vs. n=4, 1.4%, P<0.0005), cardiac failure (n=29, 36.7% vs. n=1, 2.9%, P<0.0005), diabetes mellitus (n=14, 18.2% vs. n=1, 0.9%, P=0.034), and prosthetic valve IEs (n=24, 31.2% vs. n=4, 11.4%). No differences were observed for gentamicin exposure (n=57, 64% vs. n=32, 86.5%, P=0.286). Prosthetic valve IE, cardiac failure, and vancomycin exposure were independently associated with AKI with respective odds ratio of 5.49 (95% CI 1.92-17.9), 4.37 (95% CI 4.37-465.7), and 1.084 (1.084-16.2). Mean length of hospital stay was significantly longer in patients presenting with AKI than in controls (respectively 52.4±22.1 days vs. 39.6±12.6, P<0.005). CONCLUSION: AKI is very frequent during IE, particularly in patients with prosthetic valve IE, cardiac failure, and those receiving vancomycin.

Structural transformations and physical properties of (1 - x) Na0.5Bi0.5TiO3 - x BaTiO3 solid solutions near a morphotropic phase boundary.

Piezoelectric and other physical properties are significantly enhanced at (or near) a morphotropic phase boundary (MPB) in ferroelectrics. MPB materials have attracted significant attention owing to both fundamental physics as well as the possibility of well-regulated energy and information storage devices which are dominated by lead (Pb)-based materials. Here, we report the crystal structure, Raman spectra, dielectric constant and polarization near the MPB of lead free (1 - x) Na0.5Bi0.5TiO3 - x BaTiO3 (0.00 ⩽ x ⩽ 0.10) solid-solution, prepared by sol-gel auto combustion technique and sintered by microwave sintering technique. With the addition of BaTiO3 into Na0.5Bi0.5TiO3, it induces a structural phase transition from R3c (a single phase) to R3c + P4mm (a dual phase) close to x = 0.06 and 0.07 and transform to a high symmetry tetragonal phase P4mm at higher compositions (x = 0.08 to 0.10) as evident from our x-ray Rietveld refinement and Raman spectroscopic results. We perform first-principles calculations based on density functional theory that confirm a structural transition from a rhombohedral to a tetragonal phase under increasing x. In the prepared solid solution, an anomalous enhancement of remnant polarization ([Formula: see text]) was observed for x = 0.06 and 0.07, which has been explained based on the existence of the MPB. On the other hand, the value of coercive field [Formula: see text] was found to be decreased linearly from x = 0.00 to 0.06; it is constant for higher compositions. Further details of the ferroelectric properties on the electric field poled samples have been studied and compared with the as-grown (unpoled) samples.

Brugada syndrome revealed by intestinal shigellosis in a patient from Benin at the University Hospital of Saint-Etienne.

This paper is about a Brugada syndrome (BS) of accidental discovery in a patient from Benin during an intestinal shigellosis episode in the infectiology department of university hospital of Saint-Etienne, France. Authors establish a link between these two diseases. After a literature's review, they underline that BS is under-diagnosed in Africa. Furthermore, they highlight socio-cultural characteristics of sudden deaths in West Africa including BS.

CKD-EPI equation: A suitable Glomerular Filtration Rate estimate for drug dosing in HIV-infected patients.

OBJECTIVES: To evaluate concordance between glomerular filtration rate (GFR) estimates (Cockcroft and Gault, modification of diet in renal diseases, chronic kidney disease epidemiology study group equations) for drug dosing in HIV-infected patients. PATIENTS AND METHODS: We performed a monocentric study. GFR was measured using the gold standard method (plasma clearance of iohexol) in 230 HIV-infected patients. Concordance rate was evaluated between measured GFR (mGFR) and estimated GFR (eGFR) for different GFR categories (GFR>90 mL/min, GFR<90 mL/min, GFR>70 mL/min, and GFR<70 mL/min). MDRD and CKD-EPI were used with and without indexation to body surface area (BSA). RESULTS: Mean age was 48±10 years, mean mGFR was 101±26 mL/min. Concordance between mGFR and eGFR estimated with CG, CKD-EPI (indexed and not indexed to BSA), or MDRD equations (not indexed to BSA) was similar (73%, 73%, 74%, and 73% respectively) for a breakpoint value of 90 mL/min for GFR. At this value, the concordance rate between mGFR and MDRD indexed to BSA was significantly lower (65%, P<0.05). Using 70 mL/min of GFR as the breakpoint value, all equations had similar concordance rates with mGFR (with or without indexation to BSA). CONCLUSION: CKD-EPI equation has the same concordance with GFR and with CG when used for drug dosing.

Decolonization of Staphylococcus aureus carriage.

Staphylococcus aureus nasal colonization is a well-known independent risk factor for infection caused by this bacterium. Screening and decolonization of carriers have been proven effective in reducing S. aureus infections in some populations. However, a gap remains between what has been proven effective and what is currently done. We aimed to summarize recommendations and current knowledge of S. aureus decolonization to answer the following questions: Why? For whom? How? When? And what are the perspectives?

Thallium under extreme compression.

We present a combined theoretical and experimental study of the high-pressure behavior of thallium. X-ray diffraction experiments have been carried out at room temperature (RT) up to 125 GPa using diamond-anvil cells (DACs), nearly doubling the pressure range of previous experiments. We have confirmed the hcp-fcc transition at 3.5 GPa and determined that the fcc structure remains stable up to the highest pressure attained in the experiments. In addition, HP-HT experiments have been performed up to 8 GPa and 700 K by using a combination of XRD and a resistively heated DAC. Information on the phase boundaries is obtained, as well as crystallographic information on the HT bcc phase. The equation of state (EOS) for different phases is reported. Ab initio calculations have also been carried out considering several potential high-pressure structures. They are consistent with the experimental results and predict that, among the structures considered in the calculations, the fcc structure of thallium is stable up to 4.3 TPa. Calculations also predict the post-fcc phase to have a close-packed orthorhombic structure above 4.3 TPa.

Risk factors for quinolone-resistance in women presenting with Escherichia coli acute pyelonephritis.

UNLABELLED: In France, according to the National Epidemiology Observatory of Bacterial Resistance to Antibiotics, 15.3% of outpatient urinary Escherichia coli isolates were fluoroquinolone-resistant in 2010. This puts to question the relevance of empirical fluoroquinolone therapy for community-acquired acute pyelonephritis (APN), potentially severe infections. OBJECTIVES: We had for aim to identify individual risk factors for quinolone-resistant E. coli in community-acquired APN. PATIENTS AND METHODS: A retrospective cohort study of 344 adult female patients presenting with E. coli APN was conducted at the Roanne and Saint-Etienne hospital emergency departments, from January 2011 to February 2012. We studied the demographic, administrative, and clinical factors. E. coli strains with intermediate susceptibility on the antibiogram were considered as resistant. RESULTS: There was 23% of isolates that were resistant to nalidixic acid and 17.4% to ofloxacin. Complicated APN was not a significant risk factor (univariate analysis). Three risk factors of resistance to nalidixic acid and ofloxacin were independent (multivariate analysis): fluoroquinolone use in the previous 3 months, hospitalization in the previous 6 months, and stay in a long-term care facility. The resistance to ofloxacin reached 30.6% if at least 1 of these risk factors was present; it was 9% when none of the factors were present. CONCLUSIONS: These results suggest that local recommendations for the empirical therapy of APN should be reviewed. The limitations of our study require backing up our results with prospective multicentric studies that could lead to drafting new national recommendations.

Peg-IFNα/ribavirin/protease inhibitor combination in hepatitis C virus associated mixed cryoglobulinemia vasculitis: results at week 24.

BACKGROUND: The standard-of-care treatment of patients with hepatitis C virus (HCV)-mixed cryoglobulinemia (MC) vasculitis includes pegylated interferon α (PegIFN)-α plus ribavirin and/or rituximab. About 30-40% of patients are non-responders or relapsers to such combination. OBJECTIVE: To analyse the safety and efficacy of Peg-IFNα/ribavirin/protease inhibitor combination in HCV-MC vasculitis. PATIENTS AND METHODS: Open-label, prospective, cohort study including 23 patients with HCV-MC vasculitis. Peg-IFNα/ribavirin was associated to telaprevir (375 mg three times daily, for 12 weeks, (n=15)) or boceprevir (800 mg three times daily, for 44 weeks, (n=8)) for 48 weeks. RESULTS: The median age was 59 (52.5-66) years, with 48.8% women. Thirteen patients (56.5%) were complete clinical responders, and 10 (43.5%) were partial responders at week 24. The virological response (ie, HCV RNA negativation) was of 69.6% at week 24 (p=0.005). The cryoglobulin level decreased from 0.44 to 0.06 g/l (p=0.0006) and the C4 level increased from 0.09 to 0.15 g/l (p=0.045). Grades 3 and 4 adverse events (mainly anaemia, neutropenia and thrombocytopenia) were observed in 10 cases (43.5%). Twenty patients (87%) received erythropoietin, 9 (39.1%) had red cell transfusion, and 2 (8.7%) had granulocyte stimulating agents. Antiviral therapy discontinuation was required in 8 (34.7%) patients for virological non-response (n=5), virological relapse (n=2) and depression (n=1). CONCLUSIONS: Peg-IFNα/ribavirin/protease inhibitor combination seems highly effective in HCV-MC. Such therapeutic regimen should be administered cautiously considering the high rate of side effects.

Zero-temperature phase diagram of D2 physisorbed on graphane.

We determined the zero-temperature phase diagram of D2 physisorbed on graphane using the diffusion Monte Carlo method. The substrate used was C-graphane, an allotropic form of the compound that has been experimentally obtained through hydrogenation of graphene. We found that the ground state is the δ phase, a commensurate structure observed experimentally when D2 is adsorbed on graphite, and not the registered √3 x √3 structure characteristic of H2 on the same substrate.

An algorithm based on one or two nasal samples is accurate to identify persistent nasal carriers of Staphylococcus aureus.

Persistent Staphylococcus aureus nasal carriers are at high risk of S. aureus infection. The present study delineates a simple strategy aimed at identifying rapidly and accurately this subset of subjects for clinical or epidemiological purposes. Ninety healthy volunteers were each identified as persistent, intermittent or non-nasal carriers of S. aureus by using seven specimens sampled over a 5-week period. By reference to this so-called reference standard, six other strategies aimed at simplifying and speeding the identification of persistent carriers and based on the qualitative or quantitative detection of S. aureus in one to three nasal samples were evaluated by the measure of the area under the curve of receiver operating characteristic diagrams. Among strategies using qualitative results, there was no statistical difference between protocols using seven and three samples. A threshold of 10(3) CFU of S. aureus per swab was found capable of defining persistent nasal carriage with a sensitivity of 83.1% and a specificity of 95.6%. These figures reached 95.5% and 94.9%, respectively, by using an algorithm including one or two nasal specimens according to the threshold of 10(3) CFU of S. aureus in the first swab. The latter two strategies were shown to be costly equivalents. The proposed algorithm-based strategy proved to be relevant to identify properly and consistently persistent nasal carriers of S. aureus. However, as it was built from data of healthy volunteers, it needs to be confirmed prospectively on patients potentially at risk for S. aureus infection.

The kinetics of homogeneous melting beyond the limit of superheating.

Molecular dynamics simulation is used to study the time-scales involved in the homogeneous melting of a superheated crystal. The interaction model used is an embedded-atom model for Fe developed in previous work, and the melting process is simulated in the microcanonical (N, V, E) ensemble. We study periodically repeated systems containing from 96 to 7776 atoms, and the initial system is always the perfect crystal without free surfaces or other defects. For each chosen total energy E and number of atoms N, we perform several hundred statistically independent simulations, with each simulation lasting for between 500 ps and 10 ns, in order to gather statistics for the waiting time τ(w) before melting occurs. We find that the probability distribution of τ(w) is roughly exponential, and that the mean value <τ(w)> depends strongly on the excess of the initial steady temperature of the crystal above the superheating limit identified by other researchers. The mean <τ(w)> also depends strongly on system size in a way that we have quantified. For very small systems of ~100 atoms, we observe a persistent alternation between the solid and liquid states, and we explain why this happens. Our results allow us to draw conclusions about the reliability of the recently proposed Z method for determining the melting properties of simulated materials and to suggest ways of correcting for the errors of the method.

[Lyme uveitis: 2 case reports]. / Uvéites de Lyme: à propos de 2 observations.

Lyme borreliosis is a zoonosis characterized by great clinical polymorphism. We report 2 cases in patients who presented ocular manifestations: one anterior uveitis in an adult, which resolved under treatment, and one posterior uveitis in a child, whose initial ophthalmologic examination already showed retinal fibrous scars including the macular area. Lyme disease is on the long list of causes that must be discussed in cases of uveitis. The diagnosis is based on a series of epidemiological, clinical, and biological arguments with Western Blot serological profile analysis. Treatment is based especially on intravenous antibiotics.

Is nasal carriage of Staphylococcus aureus the main acquisition pathway for surgical-site infection in orthopaedic surgery?

The endogenous or exogenous origin of Staphylococcus aureus, responsible for orthopaedic surgical-site infections (SSI), remains debated. We conducted a multicentre prospective cohort study to analyse the respective part of exogenous contamination and endogenous self-inoculation by S. aureus during elective orthopaedic surgery. The nose of each consecutive patient was sampled before surgery. Strains of S. aureus isolated from the nose and the wound, in the case of SSI, were compared by antibiotypes or pulsed-field gel electrophoresis (PFGE). A total of 3,908 consecutive patients undergoing orthopaedic surgery were included. Seventy-seven patients developed an SSI (2%), including 22 related to S. aureus (0.6%). S. aureus was isolated from the nose of 790 patients (20.2%) at the time of surgery. In the multivariate analysis, S. aureus nasal carriage was found to be a risk factor for S. aureus SSI in orthopaedic surgery. However, only nine subjects exhibiting S. aureus SSI had been found to be carriers before surgery: when compared, three pairs of strains were considered to be different and six similar. In most cases of S. aureus SSI, either an endogenous origin could not be demonstrated or pre-operative nasal colonisation retrieved a strain that was different from the one recovered from the surgical site.

Ground-state properties and superfluidity of two- and quasi-two-dimensional solid 4He.

In a recent study we have reported a new type of trial wavefunction symmetric under the exchange of particles, which is able to describe a supersolid phase. In this work, we use the diffusion Monte Carlo method and this model wavefunction to study the properties of solid (4)He in two- and quasi-two-dimensional geometries. In the purely two-dimensional (2D) case, we obtain results for the total ground-state energy and freezing and melting densities which are in good agreement with previous exact Monte Carlo calculations performed with a slightly different interatomic potential model. We calculate the value of the zero-temperature superfluid fraction ρ(s)/ρ of 2D solid (4)He and find that it is negligible in all the considered cases, similarly to what is obtained in the perfect (free of defects) three-dimensional crystal using the same computational approach. Interestingly, by allowing the atoms to move locally in the direction perpendicular to the plane where they are confined to zero-point oscillations (quasi-2D crystal), we observe the emergence of a finite superfluid density that coexists with the periodicity of the system.

Melting properties of a simple tight-binding model of transition metals. I. The region of half-filled d-band.

We present calculations of the free energy, and hence the melting properties, of a simple tight-binding model for transition metals in the region of d-band filling near the middle of a d-series, the parameters of the model being designed to mimic molybdenum. The melting properties are calculated for pressures ranging from ambient to several megabars. The model is intended to be the simplest possible tight-binding representation of the two basic parts of the energy: first, the pairwise repulsion due to Fermi exclusion; and second, the d-band bonding energy described in terms of an electronic density of states that depends on structure. In addition to the number of d-electrons, the model contains four parameters, which are adjusted to fit the pressure dependent d-band-width and the zero-temperature pressure-volume relation of Mo. We show that the resulting model reproduces well the phonon dispersion relations of Mo in the body-centered-cubic structure, as well as the radial distribution function of the high-temperature solid and liquid given by earlier first-principles simulations. Our free energy calculations start from the free energy of the liquid and solid phases of the purely repulsive pair potential model, without d-band bonding. The free energy of the full tight-binding model is obtained from this by thermodynamic integration. The resulting melting properties of the model are quite close to those given by earlier first-principles work on Mo. An interpretation of these melting properties is provided by showing how they are related to those of the purely repulsive model.