Skin lesions by Scedosporium apiospermum and Nocardia pulmonary infection in an oncologic patient: a case report

BACKGROUND

Fungal infections, other than candidiasis and aspergillosis, are an uncommon entity. Despite this, emerging pathogens are a growing threat. In the following case report, we present the case of an immunocompromised patient suffering from two serious opportunistic infections in the same episode: the first of these, Nocardia multilobar pneumonia; and the second, skin infection by Scedosporium apiospermum. These required prolonged antibacterial and antifungal treatment.

CASE PRESENTATION

This case is a 71-year-old oncological patient admitted for recurrent pneumonias that was diagnosed for Nocardia pulmonary infection. Nervous system involvement was discarded and cotrimoxazole was started. Haemorrhagic skin ulcers in the lower limbs appeared after two weeks of hospital admission. We collected samples which were positive for Scedosporium apiospermum and we added voriconazole to the treatment. As a local complication, the patient presented a deep bruise that needed debridement. We completed 4 weeks of intravenous treatment with slow improvement and continued with oral treatment until the disappearance of the lesions occurs.

CONCLUSIONS

Opportunistic infections are a rising entity as the number of immunocompromised patients is growing due to more use of immunosuppressive therapies and transplants. Clinicians must have a high suspicion to diagnose and treat them. A fluid collaboration with Microbiology is necessary as antimicrobial resistance is frequent.

MBX: A many-body energy and force calculator for data-driven many-body simulations

Many-Body eXpansion (MBX) is a C++ library that implements many-body potential energy functions (PEFs) within the "many-body energy" (MB-nrg) formalism. MB-nrg PEFs integrate an underlying polarizable model with explicit machine-learned representations of many-body interactions to achieve chemical accuracy from the gas to the condensed phases. MBX can be employed either as a stand-alone package or as an energy/force engine that can be integrated with generic software for molecular dynamics and Monte Carlo simulations. MBX is parallelized internally using Open Multi-Processing and can utilize Message Passing Interface when available in interfaced molecular simulation software. MBX enables classical and quantum molecular simulations with MB-nrg PEFs, as well as hybrid simulations that combine conventional force fields and MB-nrg PEFs, for diverse systems ranging from small gas-phase clusters to aqueous solutions and molecular fluids to biomolecular systems and metal-organic frameworks.

Toward Data-Driven Many-Body Simulations of Biomolecules in Solution: N-Methyl Acetamide as a Proxy for the Protein Backbone

The development of molecular models with quantum-mechanical accuracy for predictive simulations of biomolecular systems has been a long-standing goal in the field of computational biophysics and biochemistry. As a first step toward a transferable force field for biomolecules entirely derived from "first-principles", we introduce a data-driven many-body energy (MB-nrg) potential energy function (PEF) for N-methylacetamide (NMA), a peptide bond capped by two methyl groups that is commonly used as a proxy for the protein backbone. The MB-nrg PEF is shown to accurately describe the energetics and structural properties of an isolated NMA molecule, including the normal modes of both cis and trans isomers and the energy variation along the isomerization path, as well as the multidimensional potential energy landscape of the NMA-H₂O dimer in the gas phase. Importantly, we show that the MB-nrg PEF is fully transferable, enabling molecular dynamics simulations of NMA in solution with quantum-mechanical accuracy. Comparisons with results obtained with a popular pairwise-additive force field for biomolecules and a classical polarizable PEF demonstrate the ability of the MB-nrg PEF to accurately represent many-body effects in NMA-H₂O interactions at both short and long distances, which is key to guaranteeing full transferability from the gas phase to the liquid phase.

MB-pol(2023): Sub-chemical Accuracy for Water Simulations from the Gas to the Liquid Phase

We use the MB-pol theoretical/computational framework to introduce a new family of data-driven many-body potential energy functions (PEFs) for water, named MB-pol(2023). By employing larger 2-body and 3-body training sets, including an explicit machine-learned representation of 4-body energies, and adopting more sophisticated machine-learned representations of 2-body and 3-body energies, we demonstrate that the MB-pol(2023) PEFs achieve sub-chemical accuracy in modeling the energetics of the hexamer isomers, outperforming both the original MB-pol and q-AQUA PEFs, which currently provide the most accurate description of water clusters in the gas phase. Importantly, the MB-pol(2023) PEFs provide remarkable agreement with the experimental results for various properties of liquid water, improving upon the original MB-pol PEF and effectively closing the gap with experimental measurements.

Endocarditis caused by Neisseria bacilliformis: a case report and review of literature

A 58-years-old male with history of previous aortic prosthetic endocarditis caused by Enterococcus faecalis was admitted due to dyspnoea and fever. The two sets of blood cultures were positive for Neisseria bacilliformis. Transoesophageal echocardiography did not demonstrate endocarditis signs, but PET-CT scan showed active infection signs in the valvular aortic tube and possible infection in the aortic prosthetic valve. A six-week course of ampicillin was prescribed; gentamicin was added during the first two weeks. The patient continued a favourable clinical course. This is the 3rd described case of N. bacilliformis endocarditis and the first one in a prosthetic valve.

Hydration Structure of Na+ and K+ Ions in Solution Predicted by Data-Driven Many-Body Potentials

The hydration structure of Na⁺ and K⁺ ions in solution is systematically investigated using a hierarchy of molecular models that progressively include more accurate representations of many-body interactions. We found that a conventional empirical pairwise additive force field that is commonly used in biomolecular simulations is unable to reproduce the extended X-ray absorption fine structure (EXAFS) spectra for both ions. In contrast, progressive inclusion of many-body effects rigorously derived from the many-body expansion of the energy allows the MB-nrg potential energy functions (PEFs) to achieve nearly quantitative agreement with the experimental EXAFS spectra, thus enabling the development of a molecular-level picture of the hydration structure of both Na⁺ and K⁺ in solution. Since the MB-nrg PEFs have already been shown to accurately describe isomeric equilibria and vibrational spectra of small ion-water clusters in the gas phase, the present study demonstrates that the MB-nrg PEFs effectively represent the long-sought-after models able to correctly predict the properties of ionic aqueous systems from the gas to the liquid phase, which has so far remained elusive.

Data-Driven Many-Body Potential Energy Functions for Generic Molecules: Linear Alkanes as a Proof-of-Concept Application

We present a generalization of the many-body energy (MB-nrg) theoretical/computational framework that enables the development of data-driven potential energy functions (PEFs) for generic covalently bonded molecules, with arbitrary quantum mechanical accuracy. The "nearsightedness of electronic matter" is exploited to define monomers as "natural building blocks" on the basis of their distinct chemical identity. The energy of generic molecules is then expressed as a sum of individual many-body energies of incrementally larger subsystems. The MB-nrg PEFs represent the low-order n-body energies, with n = 1-4, using permutationally invariant polynomials derived from electronic structure data carried out at an arbitrary quantum mechanical level of theory, while all higher-order n-body terms (n > 4) are represented by a classical many-body polarization term. As a proof-of-concept application of the general MB-nrg framework, we present MB-nrg PEFs for linear alkanes. The MB-nrg PEFs are shown to accurately reproduce reference energies, harmonic frequencies, and potential energy scans of alkanes, independently of their length. Since, by construction, the MB-nrg framework introduced here can be applied to generic covalently bonded molecules, we envision future computer simulations of complex molecular systems using data-driven MB-nrg PEFs, with arbitrary quantum mechanical accuracy.

The behavior of methane-water mixtures under elevated pressures from simulations using many-body potentials

Non-polarizable empirical potentials have been proven to be incapable of capturing the mixing of methane-water mixtures at elevated pressures. Although density functional theory-based ab initio simulations may circumvent this discrepancy, they are limited in terms of the relevant time and length scales associated with mixing phenomena. Here, we show that the many-body MB-nrg potential, designed to reproduce methane-water interactions with coupled cluster accuracy, successfully captures this phenomenon up to 3 GPa and 500 K with varying methane concentrations. Two-phase simulations and long time scales that are required to fully capture the mixing, affordable due to the speed and accuracy of the MBX software, are assessed. Constructing the methane-water equation of state across the phase diagram shows that the stable mixtures are denser than the sum of their parts at a given pressure and temperature. We find that many-body polarization plays a central role, enhancing the induced dipole moments of methane by 0.20 D during mixing under pressure. Overall, the mixed system adopts a denser state, which involves a significant enthalpic driving force as elucidated by a systematic many-body energy decomposition analysis.

Anomalies and Local Structure of Liquid Water from Boiling to the Supercooled Regime as Predicted by the Many-Body MB-pol Model

For the past 50 years, researchers have sought molecular models that can accurately reproduce water's microscopic structure and thermophysical properties across broad ranges of its complex phase diagram. Herein, molecular dynamics simulations with the many-body MB-pol model are performed to monitor the thermodynamic response functions and local structure of liquid water from the boiling point down to deeply supercooled temperatures at ambient pressure. The isothermal compressibility and isobaric heat capacity show maxima near 223 K, in excellent agreement with recent experiments, and the liquid density exhibits a minimum at ∼208 K. A local tetrahedral arrangement, where each water molecule accepts and donates two hydrogen bonds, is found to be the most probable hydrogen-bonding topology at all temperatures. This work suggests that MB-pol may provide predictive capability for studies of liquid water's physical properties across broad ranges of thermodynamic states, including the so-called water's "no man's land" which is difficult to probe experimentally.

MB-Fit: Software infrastructure for data-driven many-body potential energy functions

Many-body potential energy functions (MB-PEFs), which integrate data-driven representations of many-body short-range quantum mechanical interactions with physics-based representations of many-body polarization and long-range interactions, have recently been shown to provide high accuracy in the description of molecular interactions from the gas to the condensed phase. Here, we present MB-Fit, a software infrastructure for the automated development of MB-PEFs for generic molecules within the TTM-nrg (Thole-type model energy) and MB-nrg (many-body energy) theoretical frameworks. Besides providing all the necessary computational tools for generating TTM-nrg and MB-nrg PEFs, MB-Fit provides a seamless interface with the MBX software, a many-body energy and force calculator for computer simulations. Given the demonstrated accuracy of the MB-PEFs, particularly within the MB-nrg framework, we believe that MB-Fit will enable routine predictive computer simulations of generic (small) molecules in the gas, liquid, and solid phases, including, but not limited to, the modeling of quantum isomeric equilibria in molecular clusters, solvation processes, molecular crystals, and phase diagrams.

Vapor-liquid equilibrium of water with the MB-pol many-body potential

Among the many existing molecular models of water, the MB-pol many-body potential has emerged as a remarkably accurate model, capable of reproducing thermodynamic, structural, and dynamic properties across water's solid, liquid, and vapor phases. In this work, we assessed the performance of MB-pol with respect to an important set of properties related to vapor-liquid coexistence and interfacial behavior. Through direct coexistence classical molecular dynamics simulations at temperatures of 400 K < T < 600 K, we calculated properties such as equilibrium coexistence densities, vapor-liquid interfacial tension, vapor pressure, and enthalpy of vaporization and compared the MB-pol results to experimental data. We also compared rigid vs fully flexible variants of the MB-pol model and evaluated system size effects for the properties studied. We found that the MB-pol model predictions are in good agreement with experimental data, even for temperatures approaching the vapor-liquid critical point; this agreement was largely insensitive to system sizes or the rigid vs flexible treatment of the intramolecular degrees of freedom. These results attest to the chemical accuracy of MB-pol and its high degree of transferability, thus enabling MB-pol's application across a large swath of water's phase diagram.

Highly Accurate Many-Body Potentials for Simulations of N2O5 in Water: Benchmarks, Development, and Validation

Dinitrogen pentoxide (N₂O₅) is an important intermediate in the atmospheric chemistry of nitrogen oxides. Although there has been much research, the processes that govern the physical interactions between N₂O₅ and water are still not fully understood at a molecular level. Gaining a quantitative insight from computer simulations requires going beyond the accuracy of classical force fields while accessing length scales and time scales that are out of reach for high-level quantum-chemical approaches. To this end, we present the development of MB-nrg many-body potential energy functions for nonreactive simulations of N₂O₅ in water. This MB-nrg model is based on electronic structure calculations at the coupled cluster level of theory and is compatible with the successful MB-pol model for water. It provides a physically correct description of long-range many-body interactions in combination with an explicit representation of up to three-body short-range interactions in terms of multidimensional permutationally invariant polynomials. In order to further investigate the importance of the underlying interactions in the model, a TTM-nrg model was also devised. TTM-nrg is a more simplistic representation that contains only two-body short-range interactions represented through Born-Mayer functions. In this work, an active learning approach was employed to efficiently build representative training sets of monomer, dimer, and trimer structures, and benchmarks are presented to determine the accuracy of our new models in comparison to a range of density functional theory methods. By assessing the binding curves, distortion energies of N₂O₅, and interaction energies in clusters of N₂O₅ and water, we evaluate the importance of two-body and three-body short-range potentials. The results demonstrate that our MB-nrg model has high accuracy with respect to the coupled cluster reference, outperforms current density functional theory models, and thus enables highly accurate simulations of N₂O₅ in aqueous environments.

AB0489 BETA 2 MICROGLOBULIN AS A PROGNOSTIC FACTOR IN CRYOGLOBULINEMIA NON ASSOCIATED WITH HEPATOTROPIC VIRUSES

Background:

Cryoglobulinemia (CG) is a rare phenomenon related to haematological disorders, infections and autoimmune diseases. Age and renal involvement are known prognostic markers.

Objectives:

To describe the differential clinical features and the prognostic factors in a cohort of patients diagnosed with CG non-associated with hepatotropic viruses.

Methods:

A descriptive, retrospective study of a cohort comprised of 252 cryoglobulin positive samples, obtained from the immunology laboratory database of a tertiary hospital attending 450,000 people over 1 year. 186 patients with CG positive samples were included, 87 of which were not associated with neither hepatitis B nor C virus. Demographic, clinical, serological and pathological data were collected. Nonparametric variables were compared using a Wilcoxon test.

Results:

Out of 186 reviewed patients, 87 (46.7%) are included in this study. The mean age at CG diagnosis was 60 (± 16) years. Mixed CG was the predominant subtype, detected in 66 (75.9%) patients, 10 of which (11.5%) were associated with glomerulonephritis (GN) with compatible biopsy, 17 (19.5%) with peripheral neuropathy (PN), 29 (33.3%) with non-erosive arthritis and 10 (11.5%) with leukocytoclastic vasculitis confirmed by skin biopsy. The clinical, epidemiological and serological characteristics of the sample are summarized in Table 1.

Figure 1.

Ing et al’s Nomogram of parsimonious model.

Table 1.

Clinical, epidemiological and serical characteristics of patients with CG

Sex, female / male, n (%)65/22 (74.7/25.3)Age at diagnosis, years ± SD60 ± 16CG subtype, n (%)- Type 1, n (%)27 (30)- Mixed, n (%)61 (70)ASSOCIATED DISEASES- pSS, n (%)37 (42,5)- LES, n (%)9 (10,3)- SSc, n (%)7 (8,05)CLINICAL CHARACTERISTICS- Skin, n (%)30 (34,5)- Purpura, n (%)14(16)- Ulcers, n (%)5 (5,7)- Acral ischemia, n (%)2 (2,3)- Acrocyanosis by cold, n (%)7 (8)- Raynaud, n (%)19 (21,8)- Peripheric Neuropathy, n (%)17 (19,5)- Non-erosive arthritis, n (%)29 (33,3)- Glomerulonephritis, n (%)10 (11,5)LABORATORY- β2M +(>1.8 mg/L) mean3.9- RCP (mg/L) p503.7- ESR (mm/hour) p5028- RF + (>20 UI/mL) p50124- Anti Ro52 + /Anti Ro60 + n, (%)42 (48.3)- Low C3 n, (%)48 (55.1)- Low C4 n, (%)36 (41.4)

In the comparative analysis of patients with CG and Beta 2 microglobulin (β2M), CG and rheumatoid factor (RF), those with high β2M (>1.8 mg / L) presented significantly more GN (p0.016) and PN (p0.013). However, the association of RF with either GN (p0.948) or PN (p0.645) was not significant. Also, high β2M was significantly related to complement consumption of C4 (p: 0.015) but not of C3 (p: 0.063). In the 30 (34.5%) patients with skin manifestations, high β2M showed no statistically significant association. The main systemic autoimmune diseases associated were primary Sjögren’s Syndrome (pSS) 37 (42.5%), Systemic Lupus Erythematosus (SLE) 9 (10.3%) and Systemic Sclerosis (SSc) 7 (8.05%).

Conclusion:

A direct association between presence of elevated levels of β2M and the existence of progression to glomerulonephritis and peripheral neuropathy is found in our cohort. No correlation is found between the presence of CG and other serological markers of autoimmunity except low C4. CG with elevated β2M does not associate with greater skin involvement or arthritis.

References:

[1]A.C. Desbois et al. Cryoglobulinemia: An update in 2019. Joint Bone Spine (2019)

[2]Cacoub P, Cryoglobulinemia Vasculitis, The American Journal of Medicine (2015)

Disclosure of Interests:

None declared

Low-order many-body interactions determine the local structure of liquid water

Two-body and three-body energies, modulated by higher-body terms and nuclear quantum effects, determine the structure of liquid water and require sub-chemical accuracy that is achieved by the MB-pol model but not by existing DFT functionals.

Despite its apparent simplicity, water displays unique behavior across the phase diagram which is strictly related to the ability of the water molecules to form dense, yet dynamic, hydrogen-bond networks that continually fluctuate in time and space. The competition between different local hydrogen-bonding environments has been hypothesized as a possible origin of the anomalous properties of liquid water. Through a systematic application of the many-body expansion of the total energy, we demonstrate that the local structure of liquid water at room temperature is determined by a delicate balance between two-body and three-body energies, which is further modulated by higher-order many-body effects. Besides providing fundamental insights into the structure of liquid water, this analysis also emphasizes that a correct representation of two-body and three-body energies requires sub-chemical accuracy that is nowadays only achieved by many-body models rigorously derived from the many-body expansion of the total energy, which thus hold great promise for shedding light on the molecular origin of the anomalous behavior of liquid water.

Association of a single nucleotide polymorphism in the ubxn6 gene with long-term non-progression phenotype in HIV-positive individuals

OBJECTIVES

The long-term non-progressors (LTNPs) are a heterogeneous group of HIV-positive individuals characterized by their ability to maintain high CD4⁺ T-cell counts and partially control viral replication for years in the absence of antiretroviral therapy. The present study aims to identify host single nucleotide polymorphisms (SNPs) associated with non-progression in a cohort of 352 individuals.

METHODS

DNA microarrays and exome sequencing were used for genotyping about 240 000 functional polymorphisms throughout more than 20 000 human genes. The allele frequencies of 85 LTNPs were compared with a control population. SNPs associated with LTNPs were confirmed in a population of typical progressors. Functional analyses in the affected gene were carried out through knockdown experiments in HeLa-P4, macrophages and dendritic cells.

RESULTS

Several SNPs located within the major histocompatibility complex region previously related to LTNPs were confirmed in this new cohort. The SNP rs1127888 (UBXN6) surpassed the statistical significance of these markers after Bonferroni correction (q = 2.11 × 10^-6). An uncommon allelic frequency of rs1127888 among LTNPs was confirmed by comparison with typical progressors and other publicly available populations. UBXN6 knockdown experiments caused an increase in CAV1 expression and its accumulation in the plasma membrane. In vitro infection of different cell types with HIV-1 replication-competent recombinant viruses caused a reduction of the viral replication capacity compared with their corresponding wild-type cells expressing UBXN6.

CONCLUSIONS

A higher prevalence of Ala31Thr in UBXN6 was found among LTNPs within its N-terminal region, which is crucial for UBXN6/VCP protein complex formation. UBXN6 knockdown affected CAV1 turnover and HIV-1 replication capacity.

Many-Body Effects Determine the Local Hydration Structure of Cs+ in Solution

A systematic analysis of the hydration structure of Cs⁺ ions in solution is derived from simulations carried out using a series of molecular models built upon a hierarchy of approximate representations of many-body effects in ion-water interactions. It is found that a pairwise-additive model, commonly used in biomolecular simulations, provides poor agreement with experimental X-ray spectra, indicating an incorrect description of the underlying hydration structure. Although the agreement with experiment improves in simulations with a polarizable model, the predicted hydration structure is found to lack the correct sequence of water shells. Progressive inclusion of explicit many-body effects in the representation of Cs⁺-water interactions as well as accounting for nuclear quantum effects is shown to be necessary for quantitatively reproducing the experimental X-ray spectra. Besides emphasizing the importance of many-body effects, these results suggest that molecular models rigorously derived from many-body expansions hold promise for realistic simulations of aqueous solutions.

Discontinuation of dolutegravir, elvitegravir/cobicistat and raltegravir because of toxicity in a prospective cohort

OBJECTIVES

The aim of the study was to assess the rates of discontinuation of integrase inhibitor regimens because of any neuropsychiatric adverse event (NPAE) and the factors associated with discontinuation.

METHODS

A population-based, prospective, multicentre cohort study was carried out. Treatment-naïve subjects starting therapy with a regimen containing integrase inhibitors, or those switching to such a regimen, with plasma HIV-1 RNA < 50 HIV-1 RNA copies/mL in 14 hospitals in Catalonia or the Balearic Islands (Spain) were included in the study. Every discontinuation because of adverse events (AEs) was double-checked directly with treating physicians. Multivariable Cox models identified factors correlated with discontinuation.

RESULTS

A total of 4165 subjects (37% treatment-naïve) started regimens containing dolutegravir (n = 1650; 91% with abacavir), raltegravir (n = 930) or elvitegravir/cobicistat (n = 1585). There were no significant differences among regimens in the rate of discontinuation because of any AE. Rates of discontinuation because of NPAEs were low but higher for dolutegravir/abacavir/lamivudine [2.1%; 2.9 (95% confidence interval (CI) 2.0, 4.2) discontinuations/100 patients/year] versus elvitegravir/cobicistat (0.5%; 0.8 (95% CI 0.3, 1.5) discontinuations/100 patients/year], with significant differences among centres for dolutegravir/abacavir/lamivudine and NPAEs (P = 0.003). We identified an association of female gender and lower CD4 count with increased risk of discontinuation because of any AE [Incidence ratio (IR) 2.3 (95% CI 1.4, 4.0) and 1.8 (95% CI 1.1, 2.8), respectively]. Female gender, age > 60 years and abacavir use were not associated with NPAE discontinuations. NPAEs were commonly grade 1-2, and had been present before and improved after drug withdrawal.

CONCLUSIONS

In this large prospective cohort study, patients receiving dolutegravir, raltegravir or elvitegravir/cobicistat did not show significant differences in the rate of discontinuation because of any toxicity. The rate of discontinuations because of NPAEs was low, but was significantly higher for dolutegravir than for elvitegravir/cobicistat, with significant differences among centres, suggesting that greater predisposition to believe that a given adverse event is caused by a given drug of some treating physicians might play a role in the discordance seen between cohorts.

Circulating ACE2 in Cardiovascular and Kidney Diseases

Angiotensin converting enzyme (ACE) 2 is a homologue of ACE that catalyzes the conversion of Angiotensin (Ang) II into Ang1-7, which induces vasodilation, anti-fibrotic, anti-proliferative and anti-inflammatory effects. Given that ACE2 counterbalances the effects of Ang II, it has been proposed as a biomarker in kidney disease patients. Circulating ACE2 has been studied in human and experimental studies under physiological and pathological conditions and different techniques have been assessed to determine its enzymatic activity. In patients with cardiovascular (CV) disease circulating ACE2 has been shown to be increased. In addition, hypertensive and diabetic patients have also shown higher circulating ACE2 activities. A study in type 1 diabetes patients found a negative association between circulating ACE2 and estimated glomerular filtration rate in male and female patients. Recently, it has been demonstrated that circulating ACE2 is increased in male patients with chronic kidney disease (CKD) and that it is independently associated with other classical CV risk factors, such as advanced age and diabetes. Furthermore, circulating ACE2 has been shown to be associated with silent atherosclerosis and CV outcomes in CKD patients. In diabetic nephropathy, experimental studies have demonstrated an increase in circulating ACE2 activity both at early and late stages of the disease, as well as a direct association with increased urinary albumin excretion, suggesting that it may be increased as a renoprotective mechanism in these patients. In this paper we will review the measurement of circulating ACE2 and its role in kidney disease, as well as its potential role as a renal and CV biomarker.

Bacillus species pseudo-outbreak: construction works and collateral damage

We describe the investigation and management of a pseudo-outbreak of Bacillus spp. bacteraemia associated with construction work in an emergency department (ED). During the pseudo-outbreak period 59 out of 3469 (1.7%) blood cultures yielded Bacillus spp. versus 24 out of 7628 (0.31%) in 2012. Material, surfaces, and air samples showed environmental contamination. Cases rapidly declined following the implementation of infection control measures and the end of construction. Construction works at the ED caused environmental contamination that most probably led to the pseudo-outbreak of Bacillus bacteraemia. In hospital settings, the lack of correctly implemented effective barriers during construction may place patients and healthcare providers at risk as well as lead to pseudo-outbreaks.

Population-based cohort study of variation in the use of emergency cholecystectomy for benign gallbladder diseases

Background

The aims of this prospective population-based cohort study were to identify the patient and hospital characteristics associated with emergency cholecystectomy, and the influences of these in determining variations between hospitals.

Methods

Data were collected for consecutive patients undergoing cholecystectomy in acute UK and Irish hospitals between 1 March and 1 May 2014. Potential explanatory variables influencing the performance of emergency cholecystectomy were analysed by means of multilevel, multivariable logistic regression modelling using a two-level hierarchical structure with patients (level 1) nested within hospitals (level 2).

Results

Data were collected on 4744 cholecystectomies from 165 hospitals. Increasing age, lower ASA fitness grade, biliary colic, the need for further imaging (magnetic retrograde cholangiopancreatography), endoscopic interventions (endoscopic retrograde cholangiopancreatography) and admission to a non-biliary centre significantly reduced the likelihood of an emergency cholecystectomy being performed. The multilevel model was used to calculate the probability of receiving an emergency cholecystectomy for a woman aged 40 years or over with an ASA grade of I or II and a BMI of at least 25·0 kg/m2, who presented with acute cholecystitis with an ultrasound scan showing a thick-walled gallbladder and a normal common bile duct. The mean predicted probability of receiving an emergency cholecystectomy was 0·52 (95 per cent c.i. 0·45 to 0·57). The predicted probabilities ranged from 0·02 to 0·95 across the 165 hospitals, demonstrating significant variation between hospitals.

Conclusion

Patients with similar characteristics presenting to different hospitals with acute gallbladder pathology do not receive comparable care.

Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study

It is important to know the spectrum of the microbial aetiology of prosthetic joint infections (PJIs) to guide empiric treatment and establish antimicrobial prophylaxis in joint replacements. There are no available data based on large contemporary patient cohorts. We sought to characterize the causative pathogens of PJIs and to evaluate trends in the microbial aetiology. We hypothesized that the frequency of antimicrobial-resistant organisms in PJIs has increased in the recent years. We performed a cohort study in 19 hospitals in Spain, from 2003 to 2012. For each 2-year period (2003-2004 to 2011-2012), the incidence of microorganisms causing PJIs and multidrug-resistant bacteria was assessed. Temporal trends over the study period were evaluated. We included 2524 consecutive adult patients with a diagnosis of PJI. A microbiological diagnosis was obtained for 2288 cases (90.6%). Staphylococci were the most common cause of infection (1492, 65.2%). However, a statistically significant rising linear trend was observed for the proportion of infections caused by Gram-negative bacilli, mainly due to the increase in the last 2-year period (25% in 2003-2004, 33.3% in 2011-2012; p 0.024 for trend). No particular species contributed disproportionally to this overall increase. The percentage of multidrug-resistant bacteria PJIs increased from 9.3% in 2003-2004 to 15.8% in 2011-2012 (p 0.008), mainly because of the significant rise in multidrug-resistant Gram-negative bacilli (from 5.3% in 2003-2004 to 8.2% in 2011-2012; p 0.032). The observed trends have important implications for the management of PJIs and prophylaxis in joint replacements.

[Mortality from postoperative complications (failure to rescue) after cardiac surgery in a university hospital]

OBJECTIVE

This study analyses the rate of post-operative complications after cardiac surgery, the incidence of the failure to rescue (FR), and the relationship between complications and survival.

METHODS

The study included a total of 2,750 adult patients operated of cardiac surgery between January 2003 and December 2009. An analysis was made of 9 post-operative complications. Multiple logistic regression analysis was used to find independent variables associated with any of the selected complications. Survival was analysed with Kaplan-Meyer survival estimates. A risk-adjusted Cox proportional regression model was used to find out which complications were associated with mid-term survival.

RESULTS

Hospital mortality rate was 1.4% (95% CI: 1.0%-1.9%). Postoperative complications rate was 38.5% (36.7%-40.4%), and FR 3.6% (2.5%-4.9%). Urgent surgery (OR = 2.03; 1.52-2.72), chronic renal failure (OR = 1.50, 95%.CI: 1.25-1.80), and age ≥70 years (OR = 1.42; 1.20-1.68) were the variables that showed the highest strength of association with the selected complications. Survival at 5 years in the group of patients without complications was 93%, and in the group of patients with complications it was 83% (P<.0001). Postoperative complications associated with mid-term survival were pneumonia (HR = 2.6, 95% CI; 1.27-5.50), acute myocardial infarction (HR = 1.9; 1.10-2.30), and acute renal failure (HR = 1.7; 1.30-2.26).

CONCLUSIONS

The incidence of complications after cardiac surgery is around 40%, and was associated with an increase in hospital mortality, although FR was very low (3.6%; 95% CI: 2.5-4.9).

The i-TTM model for ab initio-based ion–water interaction potentials. II. Alkali metal ion–water potential energy functions

A new set of i-TTM potential energy functions describing the interactions between alkali metal ions and water molecules is reported.

Novel CK2α and CK2β subunits in maize reveal functional diversification in subcellular localization and interaction capacity

In plants, CK2α/β subunits are encoded by multigenic families. They assemble as heterotetrameric holoenzymes or remain as individual subunits and are usually located in distinct cell compartments. Here we revise the number of maize CK2α/β genes, bringing them up to a total of eight (four CK2α catalytic and four CK2β regulatory subunits). We characterize CK2β4, which presents nuclear localization and interacts with CK2α1, CK2α3, CK2β1, and CK2β3. We also describe two CK2α isoforms (CK2α2 and CK2α4) containing N-terminal extensions that correspond to putative cTPs (chloroplast transit peptides). These cTPs are functional and responsible for the subcellular localization of CK2α2 and CK2α4 in chloroplasts. Phylogenetic analysis of the CK2α gene family, further supported by the gene structure and architecture of conserved protein domains, reveals the evolutionary expansion and diversification of this family. The subcellular localization of all four CK2α isoforms was found to be altered when were co-expressed with CK2β, thereby pointing to the latter as regulators of CK2α localization.

Gram-negative prosthetic joint infection: outcome of a debridement, antibiotics and implant retention approach. A large multicentre study

We aim to evaluate the epidemiology and outcome of gram-negative prosthetic joint infection (GN-PJI) treated with debridement, antibiotics and implant retention (DAIR), identify factors predictive of failure, and determine the impact of ciprofloxacin use on prognosis. We performed a retrospective, multicentre, observational study of GN-PJI diagnosed from 2003 through to 2010 in 16 Spanish hospitals. We define failure as persistence or reappearance of the inflammatory joint signs during follow-up, leading to unplanned surgery or repeat debridement>30 days from the index surgery related death, or suppressive antimicrobial therapy. Parameters predicting failure were analysed with a Cox regression model. A total of 242 patients (33% men; median age 76 years, interquartile range (IQR) 68-81) with 242 episodes of GN-PJI were studied. The implants included 150 (62%) hip, 85 (35%) knee, five (2%) shoulder and two (1%) elbow prostheses. There were 189 (78%) acute infections. Causative microorganisms were Enterobacteriaceae in 78%, Pseudomonas spp. in 20%, and other gram-negative bacilli in 2%. Overall, 19% of isolates were ciprofloxacin resistant. DAIR was used in 174 (72%) cases, with an overall success rate of 68%, which increased to 79% after a median of 25 months' follow-up in ciprofloxacin-susceptible GN-PJIs treated with ciprofloxacin. Ciprofloxacin treatment exhibited an independent protective effect (adjusted hazard ratio (aHR) 0.23; 95% CI, 0.13-0.40; p<0.001), whereas chronic renal impairment predicted failure (aHR, 2.56; 95% CI, 1.14-5.77; p 0.0232). Our results confirm a 79% success rate in ciprofloxacin-susceptible GN-PJI treated with debridement, ciprofloxacin and implant retention. New therapeutic strategies are needed for ciprofloxacin-resistant PJI.

Characteristics of prosthetic joint infections due to Enterococcus sp. and predictors of failure: a multi-national study

The objective of this study was to review the characteristics and outcome of prosthetic joint infections (PJI) due to Enterococcus sp. collected in 18 hospitals from six European countries. Patients with a PJI due to Enterococcus sp. diagnosed between January 1999 and July 2012 were retrospectively reviewed. Relevant information about demographics, comorbidity, clinical characteristics, microbiological data, surgical treatment and outcome was registered. Univariable and multivariable analyses were performed. A total of 203 patients met the inclusion criteria. The mean (SD) was 70.4 (13.6) years. In 59 patients the infection was diagnosed within the first 30 days (29.1%) from arthroplasty, in 44 (21.7%) between 31 and 90 days, in 54 (26.6%) between 91 days and 2 years and in 43 (21%) after 2 years. Enterococcus faecalis was isolated in 176 cases (89%). In 107 (54%) patients the infection was polymicrobial. Any comorbidity (OR 2.53, 95% CI 1.18-5.40, p 0.01), and fever (OR 2.65, 95% CI 1.23-5.69, p 0.01) were independently associated with failure. The only factor associated with remission was infections diagnosed later than 2 years (OR 0.25, 95% CI 0.09-0.71, p 0.009). In conclusion, prosthetic joint infections due to Enterococcus sp. were diagnosed within the first 2 years from arthroplasty in >70% of the patients, almost 50% had at least one comorbidity and infections were frequently polymicrobial (54%). The global failure rate was 44% and patients with comorbidities, fever, and diagnosed within the first 2 years from arthroplasty had a poor prognosis.