Quercetin: a promising virulence inhibitor of Pseudomonas aeruginosa LasB in vitro

With the inappropriate use of antibiotics, antibiotic resistance has emerged as a major dilemma for patients infected with Pseudomonas aeruginosa. Elastase B (LasB), a crucial extracellular virulence factor secreted by P. aeruginosa, has been identified as a key target for antivirulence therapy. Quercetin, a natural flavonoid, exhibits promising potential as an antivirulence agent. We aim to evaluate the impact of quercetin on P. aeruginosa LasB and elucidate the underlying mechanism. Molecular docking and molecular dynamics simulation revealed a rather favorable intermolecular interaction between quercetin and LasB. At the sub-MICs of ≤256 μg/ml, quercetin was found to effectively inhibit the production and activity of LasB elastase, as well as downregulate the transcription level of the lasB gene in both PAO1 and clinical strains of P. aeruginosa. Through correlation analysis, significant positive correlations were shown between the virulence gene lasB and the QS system regulatory genes lasI, lasR, rhlI, and rhlR in clinical strains of P. aeruginosa. Then, we found the lasB gene expression and LasB activity were significantly deficient in PAO1 ΔlasI and ΔlasIΔrhlI mutants. In addition, quercetin significantly downregulated the expression levels of regulated genes lasI, lasR, rhlI, rhlR, pqsA, and pqsR as well as effectively attenuated the synthesis of signaling molecules 3-oxo-C12-HSL and C4-HSL in the QS system of PAO1. Quercetin was also able to compete with the natural ligands OdDHL, BHL, and PQS for binding to the receptor proteins LasR, RhlR, and PqsR, respectively, resulting in the formation of more stabilized complexes. Taken together, quercetin exhibits enormous potential in combating LasB production and activity by disrupting the QS system of P. aeruginosa in vitro, thereby offering an alternative approach for the antivirulence therapy of P. aeruginosa infections. KEY POINTS: • Quercetin diminished the content and activity of LasB elastase of P. aeruginosa. • Quercetin inhibited the QS system activity of P. aeruginosa. • Quercetin acted on LasB based on the QS system.

Genomic epidemiology and ceftazidime-avibactam high-level resistance mechanisms of Pseudomonas aeruginosa in China from 2010 to 2022

Ceftazidime-avibactam (CZA) resistance is a huge threat in the clinic; however, the underlying mechanism responsible for high-level CZA resistance in Pseudomonas aeruginosa (PA) isolates remains unknown. In this study, a total of 5,763 P. aeruginosa isolates were collected from 2010 to 2022 to investigate the ceftazidime-avibactam (CZA) high-level resistance mechanisms of Pseudomonas aeruginosa (PA) isolates in China. Fifty-six PER-producing isolates were identified, including 50 isolates carrying blaPER-1 in PA, and 6 isolates carrying blaPER-4. Of these, 82.1% (46/56) were classified as DTR-PA isolates, and 76.79% (43/56) were resistant to CZA. Importantly, blaPER-1 and blaPER-4 overexpression led to 16-fold and >1024-fold increases in the MICs of CZA, respectively. WGS revealed that the blaPER-1 gene was located in two different transferable IncP-2-type plasmids and chromosomes, whereas blaPER-4 was found only on chromosomes and was carried by a class 1 integron embedded in a Tn6485-like transposon. Overexpression of efflux pumps may be associated with high-level CZA resistance in blaPER-1-positive strains. Kinetic parameter analysis revealed that PER-4 exhibited a similar kcat/Km with ceftazidime and a high (∼3359-fold) IC50 value with avibactam compared to PER-1. Our study found that overexpression of PER-1 combined with enhanced efflux pump expression and the low affinity of PER-4 for avibactam contributes to high-level resistance to CZA. Additionally, the Tn6485-like transposon plays a significant role in disseminating blaPER. Urgent active surveillance is required to prevent the further spread of high-level CZA resistance in DTR-PA isolates.

Delayed Diagnosis of Mycobacteriumbovisbacillus Calmette-Guérin Periprosthetic Joint Infection Following Total Knee Arthroplasty

Periprosthetic joint infection (PJI) can present challenges in diagnosis and treatment, particularly in the setting of atypical causative organisms such as fungi and mycobacteria. Herein, we present a case and provide a review of the diagnosis and treatment of an unusual PJI caused by bacillus Calmette-Guérin, administered during the treatment of bladder cancer 3 years prior to total knee arthroplasty and subsequent PJI. Although the patient's history of bladder cancer was known, neither his Bacillus Calmette-Guérin treatment nor its potential for distant site spread that could lead to PJI were appreciated, leading to a prolonged diagnostic evaluation and treatment course.

Antimicrobial resistance profiles of Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae strains isolated from broiler chickens

Globally, the spread of multidrug-resistant Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae from food to humans poses a severe threat to public health. The aim of this study was to assess the co-occurrence of colistin and β-lactamase resistance genes in E. coli, K. pneumoniae, and P. aeruginosa strains isolated from faeces of abattoir broiler chickens. The E. coli, P. aeruginosa and K. pneumoniae isolates were successfully detected from faecal samples by polymerase chain reaction (PCR) at infection rates of 60.7%, 22.5% and 16.7% respectively. The isolates displayed the highest levels of antibiotic resistance (AR) against ampicillin (82.3%) and amoxicillin-clavulanic acid (74.2%) for E. coli, followed by cefoxitin (70.6%) for K. pneumoniae, whilst P. aeruginosa displayed 26.1% antibiotic resistance (AR) against both ampicillin and colistin sulphate. The colistin mcr-1 gene was harboured by 46.8%, 47.1% and 21.7%, E. coli, K. pneumonia and P. aeruginosa isolates respectively. Ten out of 62 (16.1%), 6/17 (35.3%), 4/23 (17.4%) isolates were phenotypically classified as ESBL E. coli, K. pneumoniae, and P. aeruginosa respectively. The ESBL-E. coli isolates respectively possessed blaCTX-M (60%), blaTEM (20%) and blaCTX-M-9 (10%) genes. The ESBL-K. pneumoniae harboured, blaCTX-M (50%), blaOXA (33%), blaCARB (17%), and blaCTX-M-9 (17%) genes respectively, whilst, P. aeruginosa isolates respectively carried blaTEM (75%), blaCTX-M (50%), blaOXA (25%) and blaCARB (25%) genes. Molecular analysis identified the blaCTX-Mβ-lactamase-encoding genes collectively from E. coli, P. aeruginosa, K. pneumoniae isolates. Colistin and β-lactamase genes were present in only 16.7%, 6.9%, and 2.9% of E. coli, K. pneumoniae, and P. aeruginosa isolates, respectively. A total of 17, 7 and 3 isolates for E. coli, K. pneumoniae and P. aeruginosa respectively carried both colistin and β-lactamase antibiotics resistant genes. This is a public health threat that points to a challenge in the treatment of infections caused by these zoonotic bacteria. Data generated from this study will contribute to formulation of new strategies for combating spread of E. coli, K. pneumoniae, and P. aeruginosa isolates as well as prevention of their AR development.

Infections After Liver Transplant -Timeline, Management and Prevention

Liver transplantation (LT) is the standard treatment for end- stage liver disease. Patient and graft survival have improved significantly in the last three decades owing to improvement in surgical technique, better perioperative management and better immunosuppressive regimens. However, LT recipients are at increased risk of infections, particularly in the first year after transplantation. The risk of infection is directly proportional to immunosuppressive regimen and graft function. In this review, we will briefly discuss the timeline of infections after liver transplant, preventive strategies and management of infectious complications.

Nanocomposites against Pseudomonas aeruginosa biofilms: Recent advances, challenges, and future prospects

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that causes life-threatening and persistent infections in immunocompromised patients. It is the culprit behind a variety of hospital-acquired infections owing to its multiple tolerance mechanisms against antibiotics and disinfectants. Biofilms are sessile microbial aggregates that are formed as a result of the cooperation and competition between microbial cells encased in a self-produced matrix comprised of extracellular polymeric constituents that trigger surface adhesion and microbial aggregation. Bacteria in biofilms exhibit unique features that are quite different from planktonic bacteria, such as high resistance to antibacterial agents and host immunity. Biofilms of P. aeruginosa are difficult to eradicate due to intrinsic, acquired, and adaptive resistance mechanisms. Consequently, innovative approaches to combat biofilms are the focus of the current research. Nanocomposites, composed of two or more different types of nanoparticles, have diverse therapeutic applications owing to their unique physicochemical properties. They are emerging multifunctional nanoformulations that combine the desired features of the different elements to obtain the highest functionality. This review assesses the recent advances of nanocomposites, including metal-, metal oxide-, polymer-, carbon-, hydrogel/cryogel-, and metal organic framework-based nanocomposites for the eradication of P. aeruginosa biofilms. The characteristics and virulence mechanisms of P. aeruginosa biofilms, as well as their devastating impact and economic burden are discussed. Future research addressing the potential use of nanocomposites as innovative anti-biofilm agents is emphasized. Utilization of nanocomposites safely and effectively should be further strengthened to confirm the safety aspects of their application.

Enterococcal Infective Endocarditis - Post discharge treatment with continuous benzylpenicillin and ceftriaxone: A retrospective cohort study

BACKGROUND

Enterococcal Infective Endocarditis (EIE) is usually treated with the combination of penicillin/ampicillin with gentamicin or ampicillin with ceftriaxone. To enable prolonged outpatient treatment, a combination of benzylpenicillin and ceftriaxone has been suggested. This study aimed to describe the incidence and characteristics of EIE and to determine the outcome of EIE cases treated with benzylpenicillin and ceftriaxone.

METHODS

This was a retrospective single-center study including all patients diagnosed with infective endocarditis (IE) during 2016-2021, comparing EIE with IE caused by other pathogens. We described the outpatient treatment of patients with EIE, comparing those treated of benzylpenicillin - ceftriaxone with other regimes.

RESULTS

Among 222 patients with IE, 44 (20%) were diagnosed with EIE. Those were older, had a male predominance (p = 0.035), and were more disabled (p = 0.004). The incidence of EIE reached 30% towards the last year, becoming the leading etiology. Twenty-six patients received outpatient treatment, five of whom were discharged with benzylpenicillin and ceftriaxone. Adding patients from this cohort to the scarce data available, revealed similar recurrence and mortality rates compared to other treatment regimes.

CONCLUSIONS

EIE is becoming a more frequent cause of IE, involving older, more disabled patients with male predominance. Our experience and existing literature suggest that the combination of benzylpenicillin and ceftriaxone is as safe as more conventional regimes, although further research is needed.

Trends in epidemiology, surgical management, and prognosis of infective endocarditis during the XXI century in Spain: A population-based nationwide study

BACKGROUND

Few population-based studies have evaluated the epidemiology of infective endocarditis (IE). Changes in population demographics and guidelines on IE may have affected both the incidence and outcomes of IE. Therefore, the aim of our study is to provide contemporary population-based epidemiological data of IE in Spain.

METHODS

Retrospective nationwide observational study using data from the Spanish National Health System Discharge Database. We included all patients hospitalized with IE from January 2000 to December 2019.

RESULTS

A total of 64,550 IE episodes were included. The incidence of IE rose from 5.25 cases/100,000 person-year in 2000 to 7.21 in 2019, with a 2% annual percentage change (95% CI 1.3-2.6). IE incidence was higher among those aged 85 or older (43.5 cases/100.000 person-years). Trends across the study period varied with sex and age. Patients with IE were progressively older (63.9 years in 2000-2004 to 70.0 in 2015-2019, p < 0.001) and had more frequent comorbidities and predispositions, including, previous valvular prosthesis (12.1% vs 20.9%, p < 0.001). After adjustment, a progressive reduction in mortality was noted including in 2015-2019 compared to 2010-2014 (adjusted odds ratio 0.93, 95% confident interval 0.88-0.99, p = 0.023)., which was associated with more frequent cardiac surgery in recent years (15.1% in 2010-2014 vs 19.9% in 2015-2019).

CONCLUSIONS

In Spain, the incidence of IE has increased during the XXI century, with a more pronounced increase in elderly individuals. Adjusted-mortality decreased over the years, which could be related to a higher percentage of surgery. Our results highlight the changing epidemiology of IE.

The Clinical Challenge of Prosthetic Valve Endocarditis: JACC Focus Seminar 3/4

During the past 6 decades, there have been numerous changes in prosthetic valve endocarditis (PVE), currently affecting an older population and increasing in incidence in patients with transcatheter-implanted valves. Significant microbiologic (molecular biology) and imaging diagnostic (fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography) advances have been incorporated into the 2023 Duke-International Society for Cardiovascular Infectious Diseases infective endocarditis diagnostic criteria, thus increasing the diagnostic sensitivity for PVE without sacrificing specificity in validation studies. PVE is a life-threatening disease requiring management by multidisciplinary endocarditis teams in cardiac centers to improve outcomes. Novel surgical options are now available, and an increasing set of patients may avoid surgical intervention despite indication. Selected patients may complete parenteral or oral antimicrobial treatment at home. Finally, patients with prosthetic valves implanted surgically or by the transcatheter approach are candidates for antibiotic prophylaxis before invasive dental procedures.

Risk of COVID-19 death for people with a pre-existing cancer diagnosis prior to COVID-19-vaccination: A systematic review and meta-analysis

While previous reviews found a positive association between pre-existing cancer diagnosis and COVID-19-related death, most early studies did not distinguish long-term cancer survivors from those recently diagnosed/treated, nor adjust for important confounders including age. We aimed to consolidate higher-quality evidence on risk of COVID-19-related death for people with recent/active cancer (compared to people without) in the pre-COVID-19-vaccination period. We searched the WHO COVID-19 Global Research Database (20 December 2021), and Medline and Embase (10 May 2023). We included studies adjusting for age and sex, and providing details of cancer status. Risk-of-bias assessment was based on the Newcastle-Ottawa Scale. Pooled adjusted odds or risk ratios (aORs, aRRs) or hazard ratios (aHRs) and 95% confidence intervals (95% CIs) were calculated using generic inverse-variance random-effects models. Random-effects meta-regressions were used to assess associations between effect estimates and time since cancer diagnosis/treatment. Of 23 773 unique title/abstract records, 39 studies were eligible for inclusion (2 low, 17 moderate, 20 high risk of bias). Risk of COVID-19-related death was higher for people with active or recently diagnosed/treated cancer (general population: aOR = 1.48, 95% CI: 1.36-1.61, I2  = 0; people with COVID-19: aOR = 1.58, 95% CI: 1.41-1.77, I2  = 0.58; inpatients with COVID-19: aOR = 1.66, 95% CI: 1.34-2.06, I2  = 0.98). Risks were more elevated for lung (general population: aOR = 3.4, 95% CI: 2.4-4.7) and hematological cancers (general population: aOR = 2.13, 95% CI: 1.68-2.68, I2  = 0.43), and for metastatic cancers. Meta-regression suggested risk of COVID-19-related death decreased with time since diagnosis/treatment, for example, for any/solid cancers, fitted aOR = 1.55 (95% CI: 1.37-1.75) at 1 year and aOR = 0.98 (95% CI: 0.80-1.20) at 5 years post-cancer diagnosis/treatment. In conclusion, before COVID-19-vaccination, risk of COVID-19-related death was higher for people with recent cancer, with risk depending on cancer type and time since diagnosis/treatment.

Genetic determinants of antimicrobial resistance in polymyxin B resistant Pseudomonas aeruginosa isolated from airways of patients with cystic fibrosis

Pseudomonas aeruginosa is the main pathogen associated with pulmonary exacerbation in patients with cystic fibrosis (CF). CF is a multisystemic genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene, which mainly affects pulmonary function. P. aeruginosa isolated from individuals with CF in Brazil is not commonly associated with multidrug resistance (MDR), especially when compared to global occurrence, where the presence of epidemic clones, capable of expressing resistance to several drugs, is often reported. Due to the recent observations of MDR isolates of P. aeruginosa in our centers, combined with these characteristics, whole-genome sequencing was employed for analyses related to antimicrobial resistance, plasmid identification, search for phages, and characterization of CF clones. All isolates in this study were polymyxin B resistant, exhibiting diverse mutations and reduced susceptibility to carbapenems. Alterations in mexZ can result in the overexpression of the MexXY efflux pump. Mutations in oprD, pmrB, parS, gyrA and parC may confer reduced susceptibility to antimicrobials by affecting permeability, as observed in phenotypic tests. The phage findings led to the assumption of horizontal genetic transfer, implicating dissemination between P. aeruginosa isolates. New sequence types were described, and none of the isolates showed an association with epidemic CF clones. Analysis of the genetic context of P. aeruginosa resistance to polymyxin B allowed us to understand the different mechanisms of resistance to antimicrobials, in addition to subsidizing the understanding of possible relationships with epidemic strains that circulate among individuals with CF observed in other countries.

Periprosthetic bacterial and fugal infection after total knee arthroplasty with one-stage debridement: a case report

BACKGROUND

Periprosthetic infection is a serious complication after arthroplasty and is characterized by a long duration, recurrence, and a low cure rate. Although fungal infections are infrequent, they are often catastrophic, with an insidious onset, a long duration, atypical clinical symptoms, and imaging features in the early stage. They are easily misdiagnosed, or the diagnosis is missed, resulting in wrong treatment approaches.

CASE PRESENTATION

This paper reports a case involving a 62-year-old female patient of Korean ethnicity with a periprosthetic infection after knee arthroplasty who underwent joint debridement. A preoperative metagenomic next-generation sequencing of joint aspirate revealed Staphylococcus epidermidis. However, postsurgical tissue cultures confirmed the fungal infection. The patient received oral voriconazole and intra-articular injection of voriconazole for antifungal treatment. Since bacterial infection could not be ruled out, we also prescribed levofloxacin. No infection recurrence was observed after more than 22 months of follow-up. In the treatment of this patient, successful short-term follow-up was achieved, but long-term efficacy still cannot be determined.

CONCLUSIONS

In addition to the case study, we provide an analysis of the diagnosis and treatment of fungal infection after arthroplasty, especially the efficacy of debridement, antibiotics, and implant retention for a short-term outcome.

Lusutrombopag as a Repurposing Drug in Combination with Aminoglycosides against Vancomycin-Resistant Enterococcus

Due to the widespread abuse of antibiotics, drug resistance in Enterococcus has been increasing. However, the speed of antibiotic discovery cannot keep pace with the acquisition of bacterial resistance. Thus, drug repurposing is a proposed strategy to solve the crises. Lusutrombopag (LP) has been approved as a thrombopoietin receptor agonist by the Food and Drug Administration. This study demonstrated that LP exhibited significant antimicrobial activities against vancomycin-resistant Enterococcus in vitro with rare resistance occurrence. Further, LP combined with tobramycin exhibited synergistic antimicrobial effects in vitro and in vivo against Enterococcus. No in vitro or in vivo detectable toxicity was observed when using LP. Mechanism studies indicated that the disrupted proton motive force may account for LP's antimicrobial activity. In summary, these results demonstrate that LP has the previously undocumented potential to serve as an antibacterial agent against refractory infections caused by Enterococcus.

Pseudomonas fluorescens CRBSI outbreak: complying with the standardization of invasive procedures is a step ahead in the fight against antimicrobial resistance

In the healthcare sector, the implementation of standardized procedures, such as those commonly employed in franchises to ensure consistent quality, remains underprioritized. Within this framework, we focus on the importance of standardized central venous catheter (CVC) insertion procedures to prevent healthcare-associated outbreaks. While antimicrobial resistance (AMR) may still not be the most prevalent problem in some institutions, its increasing significance certainly underlines the urgency of infection prevention.We aim to highlight this issue by describing and discussing an outbreak scenario of carbapenem-resistant (CR) Pseudomonas fluorescens bloodstream infections resulting from a deviation from the standardized CVC insertion procedure. This outbreak led to six episodes of catheter related bloodstream infection (CRBSI) in patients with hematologic malignancies, delaying their primary treatment. Nineteen patients were exposed, leading to an attack rate of 31.6%.

Risk factors and mortality of carbapenem-resistant Pseudomonas aeruginosa bloodstream infection in hematology department: a ten-year retrospective study

OBJECTIVE

This study aims to investigate the risk factors for carbapenem-resistant Pseudomonas aeruginosa bloodstream infection (CRPA-BSI) and identify predictors of outcomes among patients with P. aeruginosa bloodstream infection (PA-BSI).

METHODS

A retrospective cohort study was conducted on patients with PA-BSI at Henan Cancer Hospital from 2013 to 2022.

RESULTS

Among the 503 incidences analyzed, 15.1% of them were CRPA strains. Age, ANC<100/mmc, receiving antifungal prophylaxis, exposure to carbapenems within the previous 90 days to onset of BSI, and allogeneic HSCT (allo-HSCT) were associated with the development of CRPA-BSI. CRPA-BSI patients experienced significantly higher 28-day mortality rates compared to those with carbapenem-susceptible P. aeruginosa bloodstream infection (CSPA-BSI). Multivariate logistic regression analysis identified age at BSI, active stage of hematological disease, procalcitonin levels, prior corticosteroid treatment, isolation of CRPA, and septic shock as independent predictors of 28-day mortality.

CONCLUSION

Risk factors for CRPA-BSI include age, ANC <100/mmc, antifungal prophylaxis, exposure to carbapenems, and allo-HSCT. Additionally, age at BSI, active hematological disease, procalcitonin levels, prior corticosteroid treatment, CRPA isolation, and septic shock contribute to increased mortality rates among patients with PA-BSI.

Evaluation of the Specificity of the 2023 Duke-International Society of Cardiovascular Infectious Diseases Classification for Infective Endocarditis

BACKGROUND

The 2023 Duke-ISCVID (International Society of Cardiovascular Infectious Diseases) classification is a new diagnostic tool for infective endocarditis, updating the 2000 modified Duke and the 2015 European Society for Cardiology (ESC) classifications. In comparison, its sensitivity is higher; however, its specificity remains to be evaluated and compared to that of the 2 other classifications in endocarditis suspected patients.

METHODS

We retrospectively collected the characteristics of patients hospitalized in Bichat University's Hospital, Paris, in 2021, who had been evaluated for clinical suspicion of endocarditis, have had at least a transthoracic echocardiography, 2 pairs of blood cultures, 3-month follow-up and in whom endocarditis diagnosis was finally rejected. All patients were classified by 2000 modified Duke, 2015 ESC and 2023 Duke-ISCVID, as though the endocarditis diagnosis had not been rejected.

RESULTS

In total, 130 patients' charts were analyzed. Mean age was 62 years, 84 (64.6%) were male, 39 (30.0%) had prosthetic cardiac valve or valve repair, 21 (16.2%) cardiac implanted electronic device, and 30 (23.1%) other cardiac conditions. Overall, 5, 2, and 5 patients were falsely classified as definite endocarditis with the 2000 modified Duke, 2015 ESC, and 2023 Duke-ISCVID classifications, respectively. The corresponding specificities were 96.2% (95% confidence interval [CI] [90.8%, 98.6%]), 98.5% (95% CI [93.9%, 99.7%]), and 96.2% (95% CI [90.8%, 98.6%]). The rates of possible endocarditis were of 38%, 35%, and 35% in the 3 classifications, respectively.

CONCLUSIONS

The 2023 Duke-ISCVID classification is highly specific for ruling out the diagnosis of definite infective endocarditis in patients who had been evaluated for IE.

TAK-3 Inhibits Lipopolysaccharide-Induced Neuroinflammation in Traumatic Brain Injury Rats Through the TLR-4/NF-κB Pathway

Purpose

The activation of the inflammatory response is regarded as a pivotal factor in the pathogenesis of TBI. Central nervous system infection often leads to the exacerbation of neuroinflammation following TBI, primarily caused by Gram-negative bacteria. This study aims to elucidate the effects of the novel anti-inflammatory drug TAK-3 on LPS-induced neuroinflammation in TBI rats.

Methods

In conjunction with the rat controlled cortical impact model, we administered local injections of Lipopolysaccharide to the impact site. Subsequently, interventions were implemented through intraperitoneal injections of TAK-3 and NF-κB activitor2 to modulate the TLR4/NF-κB axis The impact of LPS on neurological function was assessed using mNSS, open field test, and brain water content measurement. Inflammatory markers, including TNF-α, IL-1β, IL-6 and IL-10 were assessed to evaluate the condition of neuritis by Elisa. The activation of the TLR-4/NF-κB signaling pathway was detected by immunofluorescence staining and Western blot to assess the anti-inflammatory effects of TAK-3.

Results

The administration of LPS exacerbated neurological damage in rats with TBI, as evidenced by a reduction in motor activity and an increase in anxiety-like behavior. Furthermore, LPS induced disruption of the blood-brain barrier integrity and facilitated the development of brain edema. The activation of microglia and astrocytes by LPS at the cellular and molecular levels has been demonstrated to induce a significant upregulation of neuroinflammatory factors. The injection of TAK-3 attenuated the neuroinflammatory response induced by LPS.

Conclusion

The present study highlights the exacerbating effects of LPS on neuroinflammation in TBI through activation of the TLR-4/NF-κB signaling pathway. TAK-3 can modulate the activity of this signaling axis, thereby attenuating neuroinflammation and ultimately reducing brain tissue damage.

External Validation of the JS-BACH Classification for Predicting Outcome in Periprosthetic Joint Infections: A Cohort of 653 Patients

BACKGROUND

Periprosthetic Joint Infection (PJI) is a devastating complication in hip and knee joint arthroplasty. The "JS BACH" classification system was developed in 2021 to stratify the complexity of PJI, and more importantly, to act as a tool to guide referrals to specialist centers. The "JS BACH" classification has not been validated in an external cohort. This study aimed to do so using a large prospective cohort from Australia and New Zealand.

METHODS

We applied the JS-BACH classification to the Prosthetic Joint Infection in Australia and New Zealand Observational (PIANO) cohort. This prospective study of newly diagnosed PJI collected 2-year outcome data from 653 participants enrolled in 27 hospitals. The definition of PJI treatment failure at 24 months was any of the following: death, clinical or microbiological signs of infection, destination prosthesis removed, or ongoing antibiotic use. Individual cases were classified as per JS-BACH into "1 - uncomplicated" (n = 268), "2 - complex" (n = 330), and "3 - limited options" (n = 55). This cohort was similar to the original JS-BACH population in terms of baseline characteristics. However, there was a difference in complexity, with more DAIR (Debridement, Antibiotics, Implant Retention) procedures, fewer revision procedures, and a higher proportion of uncomplicated patients in the PIANO cohort.

RESULTS

The risk of treatment failure correlated strongly with the JS-BACH category, with odds ratios (95% CI [confidence interval]) for category 2 versus 1 of 1.75 (1.24 to 2.47) and for category 3 versus 1 of 7.12 (3.42 to 16.02).

CONCLUSION

Despite the PIANO study population being less complicated than the original derivation cohort, the JS-BACH classification showed a clear association with treatment failure in this large external cohort.

Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty

INTRODUCTION

Despite its limitations, a culture remains the "gold standard" for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI.

METHODS

This retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI.

RESULTS

A total of 526 patients were included. Of these, 125 (23.8%) were ICM positive, and 401 (76.2%) were ICM negative. Culture demonstrated an AUC of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = 0.037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM positive group.

CONCLUSION

Synovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture.

Immunoglobulins in COVID-19 pneumonia: from the acute phase to the recovery phase

BACKGROUND

COVID-19 pneumonia causes hyperinflammatory response that culminates in acute respiratory syndrome (ARDS) related to increased multiorgan dysfunction and mortality risk. Antiviral-neutralizing immunoglobulins production reflect the host humoral status and illness severity, and thus, immunoglobulin (Ig) circulating levels could be evidence of COVID-19 prognosis.

METHODS

The relationship among circulating immunoglobulins (IgA, IgG, IgM) and COVID-19 pneumonia was evaluated using clinical information and blood samples in a COVID-19 cohort composed by 320 individuals recruited during the acute phase and followed up to 4 to 8 weeks (n = 252) from the Spanish first to fourth waves.

RESULTS

COVID-19 pneumonia development depended on baseline Ig concentrations. Circulating IgA levels together with clinical features at acute phase was highly associated with COVID-19 pneumonia development. IgM was positively correlated with obesity (ρb = 0.156, P = 0.020), dyslipemia (ρb = 0.140, P = 0.029), COPD (ρb = 0.133, P = 0.037), cancer (ρb = 0.173, P = 0.007) and hypertension (ρb = 0.148, P = 0.020). Ig concentrations at recovery phase were related to COVID-19 treatments.

CONCLUSIONS

Our results provide valuable information on the dynamics of immunoglobulins upon SARS-CoV-2 infection or other similar viruses.

Antibacterial Activities of the Algal Bromophenol Methylrhodomelol Against Pseudomonas aeruginosa

Methylrhodomelol (1: ) is a bromophenol from the red alga Vertebrata lanosa that has been associated with antimicrobial properties. The aim of the current study was, therefore, to assess the antimicrobial potential of this compound in more detail against the gram-negative pathogen Pseudomonas aeruginosa. 1: exerted weak bacteriostatic activity against different strains when grown in minimal medium, whereas other phenolics were inactive. In addition, 1: (35 and 10 µg/mL) markedly enhanced the susceptibility of multidrug-resistant P. aeruginosa toward the aminoglycoside gentamicin, while it did not affect the viability of Vero kidney cells up to 100 µM. Finally, pyoverdine release was reduced in bacteria treated at sub-inhibitory concentration, but no effect on other virulence factors was observed. Transcriptome analysis of treated versus untreated P. aeruginosa indicated an interference of 1: with bacterial carbon and energy metabolism, which was corroborated by RT-qPCR and decreased ATP-levels in treated bacteria. In summary, the current study characterized the antibacterial properties of methylrhodomelol, revealed its potential as an adjuvant to standard antibiotics, and generated a hypothesis on its mode of action.

Swiss Cheese Heart: A Tale of Multiple Valve Perforations

Gerbode defect, an anomalous connection between the left ventricle and right atrium, is often congenital but can be acquired or iatrogenically formed. We present an exceedingly rare case of this defect associated with multiple valve perforation in an otherwise healthy patient with bicuspid aortic valve and endocarditis.

Spread of antibiotic resistance genes in drinking water reservoirs: Insights from a deep metagenomic study using a curated database

The exploration of antibiotic resistance genes (ARGs) in drinking water reservoirs is an emerging field. Using a curated database, we enhanced the ARG detection and conducted a comprehensive analysis using 2.2 Tb of deep metagenomic sequencing data to determine the distribution of ARGs across 16 drinking water reservoirs and associated environments. Our findings reveal a greater diversity of ARGs in sediments than in water, underscoring the importance of extensive background surveys. Crucial ARG carriers-specifically Acinetobacter, Pseudomonas, and Mycobacterium were identified in drinking water reservoirs. Extensive analysis of the data uncovered a considerable concern for drinking water safety, particularly in regions reliant on river sources. Mobile genetic elements have been found to contribute markedly to the propagation of ARGs. The results of this research suggest that the establishment of drinking water reservoirs for supplying raw water may be an effective strategy for alleviating the spread of water-mediated ARGs.

Use of chronic medications and risk of death due to COVID-19 in hospitalised patients

OBJECTIVES

To evaluate the potential association between chronic exposure to medication and death related to COVID-19.

METHODS

This is a retrospective cross-sectional study that included all patients hospitalised due to COVID-19 from 11 March to 4 June 2020 in our centre. Chronic patient medication was classified by the Anatomical Therapeutic Chemical (ATC) classification; demographic and clinical data were analysed. Multivariate logistic regression models were used to estimate the adjusted odds ratios (aOR) of death for each drug exposure; each aOR represents an independent model adjusted by clinical factors related to COVID-19 mortality.

RESULTS

The study included 978 patients with a mean (SD) age of 64.5 (17.7) years who were predominantly male (531, 54.3%). Of all 978 patients, 182 (18.61%) died during the follow-up of the study. The most common Charlson Comorbidity Index (CCI) was 0, 4.2% were smokers, 16.7% were obese, 47.4% had hypertension, and 19.4% were diabetic. Most patients (70.8%) were prescribed at least one treatment, 32.5% used >5 treatments, and 8.6% >10. Our data suggest that COVID-19 hospitalised patients taking trimethoprim and analogues, leukotriene receptor antagonists, calcineurin inhibitors, aldosterone antagonists, selective immunosuppressants, propulsives, insulins and analogues, and benzodiazepine derivatives have a higher risk of death.

CONCLUSIONS

This study investigated the association between chronic exposure to drugs and the risk of death in COVID-19 patients. Our results have shed some light on the impact of chronic drug exposure on the risk of severe COVID-19; however, further research is needed to increase the understanding about its relevance.

Assessing the impact of meropenem exposure on ceftolozane/tazobactam-resistance development in Pseudomonas aeruginosa using in vitro serial passage

BACKGROUND

Patients infected with difficult-to-treat Pseudomonas aeruginosa are likely to receive meropenem (MEM) empirically before escalation to ceftolozane/tazobactam (C/T). We assessed whether pre-exposure to MEM affected C/T resistance development on C/T exposure.

MATERIALS AND METHODS

Nine clinical P. aeruginosa isolates were exposed to MEM 16 mg/L for 72 h. Then, isolates were serially passaged in the presence of C/T (concentration of 10 mg/L) for 72 h as two groups: an MEM-exposed group inoculated with MEM pre-exposed isolates and a non-MEM control group. At 24 h intervals, samples were plated on drug-free and drug-containing agar (C/T concentration 16/8 mg/L) and incubated to quantify bacterial densities (log10 cfu/mL). Growth on C/T agar indicated resistance development, and resistant population was calculated by dividing the cfu/mL on C/T plates by the cfu/mL on drug-free agar.

RESULTS

At 72 h, resistant populations were detected in 6/9 isolates. In five isolates, MEM exposure significantly increased the prevalence of ceftolozane/tazobactam-resistance development; the percentages of resistance population were 100%, 100%, 53.5%, 31% and 3% for the MEM-exposed versus 0%, 0%, 2%, 0.35% and ≤0.0003% in the unexposed groups. One isolate had a similar resistant population at 72 h between the two groups. The remaining isolates showed no development of resistance, regardless of previous MEM exposure.

CONCLUSIONS

MEM exposure may pre-dispose to C/T resistance development and thus limit the therapeutic utility of this β-lactam/β-lactamase inhibitor. Resistance may be a result of stress exposure or molecular-level mutations conferring cross-resistance. Further in vivo studies are needed to assess clinical implications of these findings.

Differential in vitro susceptibility to ampicillin/ceftriaxone combination therapy among Enterococcus faecalis infective endocarditis clinical isolates

OBJECTIVES

To investigate the genomic diversity and β-lactam susceptibilities of Enterococcus faecalis collected from patients with infective endocarditis (IE).

METHODS

We collected 60 contemporary E. faecalis isolates from definite or probable IE cases identified between 2018 and 2021 at the University of Pittsburgh Medical Center. We used whole-genome sequencing to study bacterial genomic diversity and employed antibiotic checkerboard assays and a one-compartment pharmacokinetic-pharmacodynamic (PK/PD) model to investigate bacterial susceptibility to ampicillin and ceftriaxone both alone and in combination.

RESULTS

Genetically diverse E. faecalis were collected, however, isolates belonging to two STs, ST6 and ST179, were collected from 21/60 (35%) IE patients. All ST6 isolates encoded a previously described mutation upstream of penicillin-binding protein 4 (pbp4) that is associated with pbp4 overexpression. ST6 isolates had higher ceftriaxone MICs and higher fractional inhibitory concentration index values for ampicillin and ceftriaxone (AC) compared to other isolates, suggesting diminished in vitro AC synergy against this lineage. Introduction of the pbp4 upstream mutation found among ST6 isolates caused increased ceftriaxone resistance in a laboratory E. faecalis isolate. PK/PD testing showed that a representative ST6 isolate exhibited attenuated efficacy of AC combination therapy at humanized antibiotic exposures.

CONCLUSIONS

We find evidence for diminished in vitro AC activity among a subset of E. faecalis IE isolates with increased pbp4 expression. These findings suggest that alternate antibiotic combinations against diverse contemporary E. faecalis IE isolates should be evaluated.

Nationwide genome surveillance of carbapenem-resistant Pseudomonas aeruginosa in Japan

Japan is a country with an approximate 10% prevalence rate of carbapenem-resistant Pseudomonas aeruginosa (CRPA). Currently, a comprehensive overview of the genotype and phenotype patterns of CRPA in Japan is lacking. Herein, we conducted genome sequencing and quantitative antimicrobial susceptibility testing for 382 meropenem-resistant CRPA isolates that were collected from 78 hospitals across Japan from 2019 to 2020. CRPA exhibited susceptibility rates of 52.9%, 26.4%, and 88.0% against piperacillin-tazobactam, ciprofloxacin, and amikacin, respectively, whereas 27.7% of CRPA isolates was classified as difficult-to-treat resistance P. aeruginosa. Of the 148 sequence types detected, ST274 (9.7%) was predominant, followed by ST235 (7.6%). The proportion of urine isolates in ST235 was higher than that in other STs (P = 0.0056, χ2 test). Only 4.1% of CRPA isolates carried the carbapenemase genes: blaGES (2) and blaIMP (13). One ST235 isolate carried the novel blaIMP variant blaIMP-98 in the chromosome. Regarding chromosomal mutations, 87.1% of CRPA isolates possessed inactivating or other resistance mutations in oprD, and 28.8% showed mutations in the regulatory genes (mexR, nalC, and nalD) for the MexAB-OprM efflux pump. Additionally, 4.7% of CRPA isolates carried a resistance mutation in the PBP3-encoding gene ftsI. The findings from this study and other surveillance studies collectively demonstrate that CRPA exhibits marked genetic diversity and that its multidrug resistance in Japan is less prevailed than in other regions. This study contributes a valuable data set that addresses a gap in genotype/phenotype information regarding CRPA in the Asia-Pacific region, where the epidemiological background markedly differs between regions.

Asian Pacific Association for the Study of the Liver clinical practice guidelines on liver transplantation

Liver transplantation is a highly complex and challenging field of clinical practice. Although it was originally developed in western countries, it has been further advanced in Asian countries through the use of living donor liver transplantation. This method of transplantation is the only available option in many countries in the Asia-Pacific region due to the lack of deceased organ donation. As a result of this clinical situation, there is a growing need for guidelines that are specific to the Asia-Pacific region. These guidelines provide comprehensive recommendations for evidence-based management throughout the entire process of liver transplantation, covering both deceased and living donor liver transplantation. In addition, the development of these guidelines has been a collaborative effort between medical professionals from various countries in the region. This has allowed for the inclusion of diverse perspectives and experiences, leading to a more comprehensive and effective set of guidelines.

Invasive Candida Infection in Patients With Bacterial Infective Endocarditis

Over 21 months, 12 patients with invasive Candida infections detected during the course of treatment of bacterial endocarditis, including 11 with candidemia, were identified. Invasive Candida infections can occur as a complication of bacterial endocarditis and may occur more frequently in patients with injection drug use and broad-spectrum antibiotic exposure.

Shared Decision-Making for Partial Oral Antibiotic Treatment of Infective Endocarditis: A Case Series

Although literature has demonstrated the noninferiority of oral antibiotics in the treatment of infectious endocarditis, widespread adoption of this practice has yet to occur in the United States. We report on 32 patients with infectious endocarditis treated by a multidisciplinary endocarditis team and a standardized approach to partial oral antibiotic therapy with a high rate of clinical success.

Whole-genome characterisation of Escherichia coli isolates from patients with bacteraemia presenting with sepsis or septic shock in Spain: a multicentre cross-sectional study

BACKGROUND

Escherichia coli is the most frequent cause of bloodstream infections (BSIs). About one-third of patients with BSIs due to E coli develop sepsis or shock. The objective of this study is to characterise the microbiological features of E coli blood isolates causing sepsis or septic shock to provide exploratory information for future diagnostic, preventive, or therapeutic interventions.

METHODS

E coli blood isolates from a multicentre cross-sectional study of patients older than 14 years presenting with sepsis or septic shock (according to the Third International Consensus Definitions for Sepsis and Septic Shock criteria) from hospitals in Spain between Oct 4, 2016, and Oct 15, 2017, were studied by whole-genome sequencing. Phylogroups, sequence types (STs), serotype, FimH types, antimicrobial resistance (AMR) genes, pathogenicity islands, and virulence factors were identified. Susceptibility testing was performed by broth microdilution. The main outcome of this study was the characterisation of the E coli blood isolates in terms of population structure by phylogroups, groups (group 1: phylogroups B2, F, and G; group 2: A, B1, and C; group 3: D), and STs and distribution by geographical location and bloodstream infection source. Other outcomes were virulence score and prevalence of virulence-associated genes, pathogenicity islands, AMR, and AMR-associated genes. Frequencies were compared using χ² or Fisher's exact tests, and continuous variables using the Mann-Whitney test, with Bonferroni correction for multiple comparisons.

FINDINGS

We analysed 224 isolates: 140 isolates (63%) were included in phylogenetic group 1, 52 (23%) in group 2, and 32 (14%) in group 3. 85 STs were identified, with four comprising 44% (n=98) of the isolates: ST131 (38 [17%]), ST73 (25 [11%]), ST69 (23 [10%]), and ST95 (12 [5%]). No significant differences in phylogroup or ST distribution were found according to geographical areas or source of bloodstream infection, except for ST95, which was more frequent in urinary tract infections than in other sources (11 [9%] of 116 vs 1 [1%] of 108, p=0·0045). Median virulence score was higher in group 1 (median 25·0 [IQR 20·5-29·0) than in group 2 (median 14·5 [9·0-20·0]; p<0·0001) and group 3 (median 21 [16·5-23·0]; p<0·0001); prevalence of several pathogenicity islands was higher in group 1. No significant differences were found between phylogenetic groups in proportions of resistance to antibiotics. ST73 had higher median virulence score (32 [IQR 29-35]) than the other predominant clones (median range 21-28). Some virulence genes and pathogenicity islands were significantly associated with each ST. ST131 isolates had higher prevalence of AMR and a higher proportion of AMR genes, notably blaCTX-M-15 and blaOXA-1.

INTERPRETATION

In this exploratory study, the population structure of E coli causing sepsis or shock was similar to previous studies that included all bacteraemic isolates. Virulence genes, pathogenicity islands, and AMR genes were not randomly distributed among phylogroups or STs. These results provide a comprehensive characterisation of invasive E coli isolates causing severe response syndrome. Future studies are required to determine the contribution of these microbiological factors to severe clinical presentation and worse outcomes in patients with E coli bloodstream infection.

FUNDING

Instituto de Salud Carlos III.

Severe Community-Acquired Pneumonia in Immunocompromised Patients

Due to higher survival rates with good quality of life, related to new treatments in the fields of oncology, hematology, and transplantation, the number of immunocompromised patients is increasing. But these patients are at high risk of intensive care unit admission because of numerous complications. Acute respiratory failure due to severe community-acquired pneumonia is one of the leading causes of admission. In this setting, the need for invasive mechanical ventilation is up to 60%, associated with a high hospital mortality rate of around 40 to 50%. A wide range of pathogens according to the reason of immunosuppression is associated with severe pneumonia in those patients: documented bacterial pneumonia represents a third of cases, viral and fungal pneumonia both account for up to 15% of cases. For patients with an undetermined etiology despite comprehensive diagnostic workup, the hospital mortality rate is very high. Thus, a standardized diagnosis strategy should be defined to increase the diagnosis rate and prescribe the appropriate treatment. This review focuses on the benefit-to-risk ratio of invasive or noninvasive strategies, in the era of omics, for the management of critically ill immunocompromised patients with severe pneumonia in terms of diagnosis and oxygenation.

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

Enterococcal endocarditis management and relapses

Introduction

Enterococcus faecalis is the third micro-organism causing endocarditis and is associated with a significant relapse rate. The objective of this study was to describe the management of patients with Enterococcus faecalis endocarditis (EE) and its implication for relapses.

Methods

We conducted a monocentric, retrospective analysis of all patients hospitalized for EE including endocarditis or infection of cardiac implantable electronic device defined by the modified ESC 2015 Duke criteria in a referral centre in Paris, France.

Results

Between October 2016, and September 2022, 54 patients with EE were included, mostly men (n = 40, 74%) with a median age of 75 [68-80] years. A high risk for infective endocarditis (IE) was found in 42 patients (78%), including 14 (26%) previous histories of IE, and 32 (59%) histories of valvular cardiac surgery. The aortic valve was the most frequently affected (n = 36, 67%). Combination therapy was mainly amoxicillin-ceftriaxone during all the curative antibiotic therapy duration (n = 31, 57%). Surgery was indicated for 40 patients (74%), but only 27 (50%) were operated on, mainly due to their frailty. Among the 17 deaths (32%), six (11%) happened during the first hospitalization for EE. A suppressive antibiotic treatment was initiated in 15 (29%) patients, mostly because of not performing surgery. During the 6-year study period an EE relapse occurred in three (6%) patients.

Conclusions

EE is a worrying disease associated with a high risk of relapse and significant mortality. Suppressive antibiotic therapy could be a key treatment to limit the occurrence of relapses.

Quercetin attenuates Pseudomonas aeruginosa-induced acute lung inflammation by inhibiting PI3K/AKT/NF-κB signaling pathway

Pseudomonas aeruginosa is an opportunistic pathogen that commonly causes infections in immunocompromised individuals with significant morbidity and mortality. Quercetin is a natural flavonoid abundantly present in fruits and vegetables, exerting potent anti-inflammatory effects in treatment of various diseases. However, the molecular mechanisms of quercetin in treatment of P. aeruginosa-induced acute lung inflammation are unclear. In this study, we exploited network pharmacology- and molecular docking-based approach to explore the potential mechanisms of quercetin against P. aeruginosa pneumonia, which was further validated via in vivo and in vitro experiments. The in vivo experiments demonstrated that quercetin alleviated the P. aeruginosa-induced lung injury by diminishing neutrophil infiltration and production of proinflammatory cytokines (IL-1β, IL-6, and TNF), which was associated with decreased mortality. Moreover, the quercetin-treated mice displayed decreased phosphorylation levels of PI3K, AKT, IκBα, and NF-κB p65 in lung tissues compared to non-drug-treated mice. Similarly, the in vitro study showed that the phosphorylation of these regulatory proteins and production of the proinflammatory cytokines were impaired in the quercetin-pretreated macrophages upon P. aeruginosa infection. Altogether, this study suggested that quercetin reduced the P. aeruginosa-induced acute lung inflammation by suppressing PI3K/AKT/NF-κB signaling pathway.

Mural infective endocarditis with a mass on the fossa ovalis in the right atrium

Infective endocarditis (IE) is a life-threatening disease that affects the endocardial surface of the heart. Although heart valves are commonly involved in IE, in rare cases, vegetation is attached to the cardiac walls without valvular endocardial involvement, which is referred to as mural IE. In this case, a 60-year-old female presented with a seven-day history of fever associated with worsening pain in the right shoulder and left hip. Streptococcus dysgalactiae subsp. Equisimilis was detected in both blood and joint fluid cultures. Although transthoracic echocardiography revealed no mass, transesophageal echocardiography revealed a mobile mass in the fossa ovalis of the right atrium. She was subsequently diagnosed with mural IE and successfully treated with antibiotics without cardiac surgery. To our knowledge, only a few reports have described mural IE with vegetation in or around the fossa ovalis of the right atrium. This case highlights the importance of transesophageal echocardiography in diagnosing mural IE. The treatment strategy for mural IE should be discussed individually and in a multidisciplinary manner because current IE guidelines may not be applicable to mural IE cases due to differences in disease characteristics and clinical course between mural and valvular IE.

Fosfomycin as salvage therapy for persistent methicillin-resistant Staphylococcus aureus bacteremia: A case series and review of the literature

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia can be persistent and refractory; however, the optimal approach for its treatment has not been determined. Although fosfomycin (FOM) has been shown to have synergistic effects with anti-MRSA agents in vitro, clinical experience with FOM combination therapy is limited. Thus, we present cases of persistent MRSA bacteremia that improved with the addition of FOM. In case 1, a 48-year-old man with prosthetic vascular graft infection developed persistent MRSA bacteremia despite vancomycin (VCM) and daptomycin (DAP) administration. On day 46, after the first positive blood culture, we added FOM to DAP. The blood culture became negative on day 53. In case 2, an 85-year-old woman presented with pacemaker-related MRSA bacteremia. She was treated with VCM, followed by DAP and DAP plus rifampicin. However, the bacteremia persisted for 32 days because of difficulties in immediate pacemaker removal. After adding FOM to DAP, the blood culture became negative on day 38. In case 3, a 57-year-old woman developed persistent MRSA bacteremia due to pulmonary valve endocarditis and pulmonary artery thrombosis after total esophagectomy for esophageal cancer. The bacteremia continued for 50 days despite treatment with DAP, followed by VCM, VCM plus minocycline, DAP plus linezolid (LZD), and VCM plus LZD. She was managed conservatively because of surgical complications. After adding FOM to VCM on day 51, the blood culture became negative on day 58. FOM combination therapy may be effective in eliminating bacteria and can serve as salvage therapy for refractory MRSA bacteremia.

Infective Endocarditis Caused by Staphylococcus lugdunensis

Staphylococcus lugdunensis, a minor species of coagulase-negative staphylococci, has attracted attention because of its formidable pathogenicity. We present a case of infective endocarditis (IE) caused by S. lugdunensis in a 72-year-old woman with a history of breast cancer and metastases who presented with fever. Two of two blood culture bottles were positive for gram-positive cocci. Transesophageal echocardiography revealed vegetation attached to the right cusp of the aortic valve and an abscess in the annulus, which was less evident on transthoracic echocardiography. This case underscores the importance of considering S. lugdunensis as a potential cause of IE.

Prolonged suppressive antibiotic therapy for inferior vena cava filter infection following emphysematous pyelonephritis and cystitis: a case report

Introduction and importance

Infections of inferior vena cava (IVC) filters are rare. The authors present a case of IVC filter infection following concurrent emphysematous urinary tract infections that was finally treated with prolonged suppressive antibiotic therapy (PSAT).

Case presentation

A 68-year-old man with pemphigoid and type 2 diabetes mellitus, who had undergone IVC filter placement, was transferred with decreased consciousness, respiratory failure, and hypotension. Computed tomography revealed gas in the left renal parenchyma and bladder wall, suggesting a diagnosis of concurrent emphysematous pyelonephritis and cystitis. While blood and urine cultures were positive for extended-spectrum beta-lactamase-producing Escherichia coli, and the patient's general condition improved with proper antibiotic therapy, bacteremia persisted until day 10 from symptom onset. After ruling out abscesses and infectious endocarditis, the cause of persistent bacteremia was suspected to be IVC filter infection. As the IVC had been placed 12 years before, the authors did not remove it to avoid complications. PSAT with sulfamethoxazole-trimethoprim was continued after 6 weeks of intravenous antibiotic therapy. The patient had an uneventful course over the year following hospital discharge.

Clinical discussion

PSAT is considered for device-related infections in patients with cardiac assist devices and artificial joints when the infection flares up or recurs even after antibiotic treatment of an adequate duration. There is no consensus regarding the optimal duration of antimicrobial therapy for IVC filter infections.

Conclusion

Infections of implanted devices, such as IVC filters, secondary to severe infections can cause persistent bacteremia. PSAT may be an alternative option to treat IVC filter infection, when the IVC filter is considered difficult to remove.

Pseudomonasaeruginosa antimicrobial susceptibility profiles, resistance mechanisms and international clonal lineages: update from ESGARS-ESCMID/ISARPAE Group

SCOPE

Pseudomonas aeruginosa, a ubiquitous opportunistic pathogen considered one of the paradigms of antimicrobial resistance, is among the main causes of hospital-acquired and chronic infections associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of P. aeruginosa to develop antimicrobial resistance through chromosomal mutations, the increasing prevalence of transferable resistance determinants (such as the carbapenemases and the extended-spectrum β-lactamases), and the global expansion of epidemic lineages. The general objective of this initiative is to provide a comprehensive update of P. aeruginosa resistance mechanisms, especially for the extensively drug-resistant (XDR)/difficult-to-treat resistance (DTR) international high-risk epidemic lineages, and how the recently approved β-lactams and β-lactam/β-lactamase inhibitor combinations may affect resistance mechanisms and the definition of susceptibility profiles.

METHODS

To address this challenge, the European Study Group for Antimicrobial Resistance Surveillance (ESGARS) from the European Society of Clinical Microbiology and Infectious Diseases launched the 'Improving Surveillance of Antibiotic-Resistant Pseudomonas aeruginosa in Europe (ISARPAE)' initiative in 2022, supported by the Joint programming initiative on antimicrobial resistance network call and included a panel of over 40 researchers from 18 European Countries. Thus, a ESGARS-ISARPAE position paper was designed and the final version agreed after four rounds of revision and discussion by all panel members.

QUESTIONS ADDRESSED IN THE POSITION PAPER

To provide an update on (a) the emerging resistance mechanisms to classical and novel anti-pseudomonal agents, with a particular focus on β-lactams, (b) the susceptibility profiles associated with the most relevant β-lactam resistance mechanisms, (c) the impact of the novel agents and resistance mechanisms on the definitions of resistance profiles, and (d) the globally expanding XDR/DTR high-risk lineages and their association with transferable resistance mechanisms.

IMPLICATION

The evidence presented herein can be used for coordinated epidemiological surveillance and decision making at the European and global level.

Pneumonia in childhood bacterial meningitis-Experience from three continents

INTRODUCTION

Although concomitant pneumonia is sometimes diagnosed in childhood bacterial meningitis, its role in the illness course and prognosis is not known. We examined these associations using prospectively collected data from Finland, Latin America and Angola.

METHODS

This was a secondary descriptive analysis of prospectively collected data (clinical and laboratory findings at admission, during hospitalisation and outcome) from five clinical bacterial meningitis trials. We included children aged 2 months to 15 years from sites with confirmed bacterial meningitis and potential concomitant pneumonia (diagnosed clinically with or without a chest radiograph).

RESULTS

Pneumonia was not observed in the 341 children included in Finland. Pneumonia was observed in 8% (51/606) of children in Latin America and in 46% (377/819) in Angola (p < 0.0001). In multivariate analyses, predisposing factors for pneumonia in Latin America were age <1 year, seizures and severe anaemia; the corresponding factors for Angola were preadmission duration of illness >3 days and non-meningococcal meningitis. Concomitant pneumonia increased the severity of the disease and disabling sequelae.

CONCLUSION

Bacterial meningitis with pneumonia is a major, previously undescribed entity of severe bacterial meningitis, especially in Angola.

Brush-Like Coatings Provide a Cloak of Invisibility to Titanium Implants

Orthopedic implants such as knee and hip implants are one of the most important types of medical devices. Currently, the surface of the most advanced implants consists of titanium or titanium-alloys with high porosity at the bone-contacting surface leading to superior mechanical properties, excellent biocompatibility, and the capability of inducing osseointegration. However, the increased surface area of porous titanium provides a nidus for bacteria colonization leading to implant-related infections, one of the main reasons for implant failure. Here, two readily applicable titanium-coatings based on hydrophilic carboxybetaine polymers that turn the surface stealth thereby preventing bacterial adhesion and colonization are developed. These coatings are biocompatible, do not affect cell functionality, exhibit great antifouling properties, and do not cause additional inflammation during the healing process. In this way, the coatings can prevent implant-related infections, while at the same time being completely innocuous to its biological environment. Thus, these coating strategies are a promising route to enhance the biocompatibility of orthopedic implants and have a high potential for clinical use, while being easy to implement in the implant manufacturing process.

Rate of severe and fatal infections in a cohort of patients with interstitial lung disease associated with rheumatoid arthritis: a multicenter prospective study

Objective

To describe severe infection, foci of infection, microorganisms, associated factors, and impact on mortality in patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD).

Patients and methods

The study was based on a multicenter prospective cohort of patients with RA-ILD followed up from 2015 to 2023. The main outcome measures were incident severe infection and fatal infection. We evaluated infectious foci, etiologic agents, vaccination status, variables associated with lung function, and clinical-therapeutic variables in RA. The incidence rate (IR) for infection and mortality was calculated per 100 person-years, and 3 multivariate models were constructed to explore factors associated with infection.

Results

We followed up 148 patients with RA-ILD for a median 56.7 months (699.3 person-years). During this period, 142 patients (96%) had at least 1 infection. A total of 368 infectious episodes were recorded, with an IR of 52.6 per 100 person-years. Of the 48 patients who died, 65% did so from infection. Respiratory infections were the most common first infection (74%), infection overall (74%), and fatal infection (80%) and were caused mostly by SARS CoV-2, Streptococcus pneumoniae, Pseudomonas aeruginosa, and influenza A virus. The factors associated with an increased risk of infection and death in patients with RA-ILD were age, inflammatory activity, and therapy with corticosteroids and immunosuppressants.

Conclusion

Patients with RA-ILD have a high risk of serious infection, especially respiratory infection. Infection develops early, is recurrent, and is frequently fatal. The presence of associated factors such as advanced age, joint inflammation, and treatment highlight the importance of integrated and preventive medical care.

Novel method for determination of colistin sulfate in human plasma by high-performance liquid chromatography-tandem mass spectrometry and its clinical applications in critically ill patients

Colistin is a last-resort antibiotic used for treating infections caused by carbapenem-resistant Gram-negative bacteria, particularly in critically patients, nevertheless its therapeutic window is narrow, and requires monitoring. A determination method suitable for clinical detection is conducive to ensure its efficacy and safety of patients with severe infection. We developed and validated a concise and accurate high-performance liquid chromatography-tandem mass spectrometry method for the determination of colistin A and B in human plasma. We used a Kinetex C18 column (50 mm × 2.1 mm, 2.6 μm) with acetonitrile (containing 0.1% formic acid) as the protein precipitant and water (containing 0.2% formic acid and 5 mmol/L ammonium formate) - acetonitrile (containing 0.2% formic acid) as the gradient elution. The calibration curves were linear over concentration ranges of 0.06-4.00 μg/ml (colistin A) and 0.1-7.0 μg/ml (colistin B). The precision, accuracy, matrix effect, extraction recovery, and stability were all validated. This method was applied to the therapeutic drug monitoring for 50 critically ill patients. The trough, peak, and average steady-state concentrations of these patients were 0.8 ± 0.4, 1.4 ± 0.5, and 1.0 ± 0.4 μg/ml, respectively. And the concentrations of colistin in human plasma were closely related to the patient's renal function.

Characterization of a hemolytic and antibiotic-resistant Pseudomonas aeruginosa strain S3 pathogenic to fish isolated from Mahananda River in India

Virulent strain Pseudomonas aeruginosa isolated from Mahananda River exhibited the highest hemolytic activity and virulence factors and was pathogenic to fish as clinical signs of hemorrhagic spots, loss of scales, and fin erosions were found. S3 was cytotoxic to the human liver cell line (WRL-68) in the trypan blue dye exclusion assay. Genotype characterization using whole genome analysis showed that S3 was similar to P. aeruginosa PAO1. The draft genome sequence had an estimated length of 62,69,783 bp, a GC content of 66.3%, and contained 5916 coding sequences. Eight genes across the genome were predicted to be related to hemolysin action. Antibiotic resistance genes such as class C and class D beta-lactamases, fosA, APH, and catB were detected, along with the strong presence of multiple efflux system genes. This study shows that river water is contaminated by pathogenic P. aeruginosa harboring an array of virulence and antibiotic resistance genes which warrants periodic monitoring to prevent disease outbreaks.

Preventive nasal administration of flagellin restores antimicrobial effect of gentamicin and protects against a multidrug-resistant strain of Pseudomonas aeruginosa

The increasing prevalence of multidrug-resistant Pseudomonas aeruginosa (PA) is a significant concern for chronic respiratory disease exacerbations. Host-directed drugs, such as flagellin, an agonist of toll-like receptor 5 (TLR5), have emerged as a promising solution. In this study, we evaluated the prophylactic intranasal administration of flagellin against a multidrug-resistant strain of PA (PAMDR) in mice and assessed the possible synergy with the antibiotic gentamicin (GNT). The results indicated that flagellin treatment before infection decreased bacterial load in the lungs, likely due to an increase in neutrophil recruitment, and reduced signs of inflammation, including proinflammatory cytokines. The combination of flagellin and GNT showed a synergistic effect, decreasing even more the bacterial load and increasing mice survival rates, in comparison to mice pre-treated only with flagellin. These findings suggest that preventive nasal administration of flagellin could restore the effect of GNT against MDR strains of PA, paving the way for the use of flagellin in vulnerable patients with chronic respiratory diseases.

Novel β-lactam-β-lactamase inhibitors as monotherapy versus combination for the treatment of drug-resistant Pseudomonas aeruginosa infections: A multicenter cohort study

BACKGROUND

Data comparing the clinical outcomes of novel β-lactam-β-lactamase inhibitors given in combination versus monotherapy for the treatment of multidrug-resistant (MDR) P. aeruginosa infections are lacking.

METHOD

This retrospective cohort study included patients who received novel β-lactam-β-lactamase inhibitors as monotherapy or in combination for the treatment of MDR P. aeruginosa infections. The study was conducted between 2017 and 2022 in 6 tertiary care hospitals in Saudi Arabia. Overall in-hospital mortality, 30-day mortality, clinical cure, and acute kidney injury (AKI) were compared between recipients of monotherapy versus combination using multivariate logistic regression analysis.

RESULT

118 patients and 82 patients were included in monotherapy and combination therapy arms, respectively. The cohort represented an ill population with 56% in the intensive care unit and 37% in septic shock. A total of 19% of patients presented with bacteremia. Compared to monotherapy, combination therapy did not significantly differ in clinical cure (57% vs. 68%; P = 0.313; OR, 0.63; 95% CI, 0.36-1.14) in-hospital mortality (45% vs. 37%; P = 0.267; OR, 1.38; 95% CI, 0.78-2.45), or 30-day mortality (27% vs. 24%; P = 0.619; OR, 1.18; 95% CI, 0.62-1.25). However, AKI (32% vs. 12%; P = 0.0006; OR, 3.45; 95% CI, 1.67-7.13) was significantly more common in patients who received combination therapy.

CONCLUSION

Novel β-lactam-β-lactamase inhibitors when used in combination with other antibiotics did not add clinical benefit compared to their use as monotherapy in the treatment of MDR P. aeruginosa infections. A Combination regimen was associated with an increased risk of nephrotoxicity.

Calcium polystyrene sulfonate-induced rectal ulcer causing E. coli native-valve infective endocarditis

Escherichia coli-associated native-valve infective endocarditis is a rare disease that affects elderly patients with underlying risk factors such as diabetes mellitus, malignancy, and renal failure. Long-term use of calcium polystyrene sulfonate is a potential risk factor for gastrointestinal mucosal damage or even colorectal ulcers. Herein, we describe a fatal case of a 66-year-old Japanese man with diabetes mellitus and renal failure who was prescribed calcium polystyrene sulfonate (CPS) for 11 years and developed a CPS-induced rectal ulcer, leading to E. coli native-valve infective endocarditis. The patient was admitted to our hospital due to acute-onset impaired consciousness. As a result of the systemic investigation, he was diagnosed with E. coli bacteremia accompanied by multiple cerebral infarctions and an acute hemorrhagic rectal ulcer. Transesophageal echocardiography revealed a 20-mm vegetative structure on the mitral valve, resulting in a final diagnosis of E. coli-associated infective endocarditis. After rectal resection, mitral valve replacement surgery was performed; however, the patient died shortly after surgery. Pathological findings of the resected rectum showed deposition of a basophilic crystalline material suggesting the presence of CPS. Our case highlights the potential risk of colorectal ulcers in a long-term CPS user, which can trigger bacterial translocation and endocarditis as fatal complications.

Lower Rates of Re-Operation Following Partial or Complete Revision Arthroplasty Compared to Debridement, Antibiotics, and Implant Retention for Early Postoperative and Acute Hematogenous Periprosthetic Hip Infection

INTRODUCTION

This study aimed to: 1) compare treatment outcomes between debridement, antibiotics, and implant retention (DAIR) and partial or complete revision arthroplasty (RA) for early postoperative and acute hematogenous total hip arthroplasty (THA) periprosthetic joint injection (PJI) and 2) identify factors associated with treatment outcome.

METHODS

The study consisted of a retrospective cohort of patients who underwent surgery for PJI between 2004 and 2021. There were 76 patients (74.5%) who underwent DAIR and 26 patients (25.5%) who underwent RA. Treatment success was defined as treatment eradication at a minimum of a 2-year follow up. Bivariate regression analysis was used to assess the effect of different factors on treatment outcomes. Kaplan-Meier survivorship was performed to compare survivorship between cohorts.

RESULTS

At a mean follow-up of 8.2 years (range, 2.2 to 16.4 years), significantly more DAIR failed treatment (DAIR, 50 [65.8%]; 10 [38.5%]; P = 0.015). The 8-year Kaplan-Meier survivorship was 35.1% [95% CI (confidence interval), 24.3 to 45.9] for patients treated with DAIR and 61.5% [95% CI, 42.9 to 80.1] for those treated with RA (Log Rank = 0.039). Bivariate regression analysis showed performing a RA was associated with a higher likelihood of treatment success (OR [odds ratio] 4.499, 95% CI 1.600 to 12.647, P = 0.004), whereas a higher BMI (Body Mass Index) was associated with treatment failure (OR 0.934, 95% CI 0.878 to 0.994, P = 0.032).

CONCLUSION

To reduce the rate of recalcitrant infection following early postoperative or acute hematogenous THA PJI, RA may be of benefit over DAIR. This is especially relevant in the early post-operative period, when components can be readily exchanged.

Systematic Dental Screening Before Transcatheter Aortic Valve Replacement: A Call to Action!

Transcatheter aortic valve implantation (TAVR) offers an alternative to surgical aortic valve replacement for high-risk patients. Despite its benefits, concerns arise from its association with prosthetic valve endocarditis (PVE), a severe complication. Recent studies indicate a potential higher incidence of PVE in TAVR recipients, especially within the first year postimplantation. A significant proportion of these cases trace back to oral-pharyngeal bacteria. However, no consensus exists on dental screening for TAVR, unlike the standard procedure for surgical aortic valve replacement. Dental screenings could reduce PVE risks and aid in patient recovery. This article underscores the importance of dental screenings, calling for more research to establish its efficacy and systematic application for TAVRI candidates. Collaborative efforts between oral and maxillofacial surgeons and cardiologists are crucial for optimal patient outcomes.