Candida and cardiovascular implantable electronic devices: a case of lead and native aortic valve endocarditis and literature review

Coating CoCrMo Alloy with Graphene Oxide and ε-Poly-L-Lysine Enhances Its Antibacterial and Antibiofilm Properties

INTRODUCTION

With increases in implant infections, the search for antibacterial and biofilm coatings has become a new interest for orthopaedists and dentists. In recent years, graphene oxide (GO) has been extensively studied for its superior antibacterial properties. However, most of these studies have focused on solutions and there are few antibacterial studies on metal surfaces, especially the surfaces of cobalt-chromium-molybdenum (CoCrMo) alloys. ε-Poly-L-lysine (ε-PLL), as a novel food preservative, has a spectrum of antimicrobial activity; however, its antimicrobial activity after coating an implant surface is not clear.

METHODS

In this study, for the first time, a two-step electrodeposition method was used to coat GO and ε-PLL on the surface of a CoCrMo alloy. Its antibacterial and antibiofilm properties against S. aureus and E. coli were then studied.

RESULTS

The results show that the formation of bacteria and biofilms on the coating surface was significantly inhibited, GO and ε-PLL composite coatings had the best antibacterial and antibiofilm effects, followed by ε-PLL and GO coatings. In terms of classification, the coatings are anti-adhesive and contact-killing/inhibitory surfaces. In addition to oxidative stress, physical damage to GO and electrostatic osmosis of ε-PLL are the main antibacterial and antibiofilm mechanisms.

DISCUSSION

This is the first study that GO and ε-PLL coatings were successfully prepared on the surface of CoCrMo alloy by electrodeposition. It provides a promising new approach to the problem of implant infection in orthopedics and stomatology.

Antibacterial and antibiofilm properties of graphene and its derivatives

Infections resulting from bacteria and biofilms have become a huge problem threatening human health. In recent years, the antibacterial and antibiofilm effects of graphene and its derivatives have been extensively studied. However, there continues to be some controversy over whether graphene and its derivatives can resist infection and biofilms. Moreover, the antibacterial mechanism and cytotoxicity of graphene and its derivatives are unclear. In the present review, antibacterial and antibiofilm abilities of graphene and its derivatives in solution, on the surface are reviewed, and their toxicity and possible mechanisms are also reviewed. Furthermore, we propose possible future development directions for graphene and its derivatives in antibacterial and antibiofilm applications.

Management of systemic fungal infections in the presence of a cardiac implantable electronic device: A systematic review

Evidence to inform the management of systemic fungal infections in the setting of a cardiac implantable electronic devices (CIED), such as a permanent pacemaker or implantable cardioverter-defibrillator, is scant and limited to case reports and series. The available literature suggests high morbidity and mortality. To better characterize the shared experience of these cases and their outcomes, we performed a systematic review. We investigated all published reports of systemic fungal infections-fungemia and fungal vegetative disease-in the context of CIED, drawing from PubMed, EMBASE, and the Cochrane database of systematic reviews, inclusive of patients who received treatment between January 2000 and May 2020. Exclusion criteria included presence of ventricular assist device and concurrent bacteremia, bacterial endocarditis, bacterial vegetative infection, or viremia. Among 6261 screened articles, 48 cases from 41 individual studies were identified. Candida and Aspergillus species were the most commonly isolated fungi. There was significant heterogeneity in antifungal medication selection and duration. CIED extraction-either transvenous or surgical-was associated with increased survival to hospital discharge (92%) and clinical recovery at latest follow-up (81%), compared to cases where CIED extraction was deferred (56% and 40%, respectively). Importantly, there were no prospective data, and the data were limited to individual case reports and one small case series. In summary, CIED extraction is associated with improved fungal clearance and patient survival. Reported antifungal regimens are heterogeneous and nonuniform. Prospective studies are needed to verify these results and define optimal antifungal regimens.

Candidemia in patients with cardiovascular implantable electronic devices

PURPOSE

Current guidelines recommend complete extraction of cardiovascular implantable electronic devices (CIEDs) in the case of persistent or recurrent fungemia without other identifiable sources, though supporting evidence is lacking. We sought to evaluate the prognosis of patients with candidemia and CIEDs.

METHODS

Twelve consecutive patients (54 ± 12 years, 8 male) with CIED and concurrent candidemia were reviewed.

RESULTS

At the time of diagnosis with candidemia, seven patients were immunocompromised, six were on long-term antibacterial therapy, two were intravenous drug users, four were on chronic hemodialysis, and six had a central venous catheter. Four patients were confirmed as definite CIED infection as vegetation was visible on lead by echocardiogram. The other 8 patients were considered possible CIED infection with candidemia of unknown focus. All patients with visible vegetation underwent CIED removal without complications, and other patients were initially managed non-operatively. After 1 year of follow-up, 7 patients had died and at extended follow-up, all patients without lead removal died while 3 of 4 patients with lead extraction survived. Of note, 50% of deaths in the patients without lead removal were associated with fungal sepsis.

CONCLUSIONS

Candida fungemia is associated with a high mortality. CIED removal should be an early consideration in these patients even if lead vegetations are not seen.

Candida tropicalis defibrillator endocarditis: A case report and review of current literature

We provide a review of current literature and report on a case of electronic device infective endocarditis with C. tropicalis. A 64-year-old man presented for revision of his implantable cardioverter defibrillator. Echocardiography revealed extensive vegetations attached to the Eustachian valve and in the right ventricular apex. Microbiological findings presented C. tropicalis on the explanted material. The patient refused additional surgical intervention. We successfully treated the patient with liposomal Amphotericin B and Flucytosine for 8 weeks.

Hydrophobicity of graphene as a driving force for inhibiting biofilm formation of pathogenic bacteria and fungi

OBJECTIVE

To evaluate the surface and wettability characteristics and the microbial biofilm interaction of graphene coating on titanium.

METHODS

Graphene was deposited on titanium (Control) via a liquid-free technique. The transfer was performed once (TiGS), repeated two (TiGD) and five times (TiGV) and characterized by AFM (n=10), Raman spectroscopy (n=10), contact angle and SFE (n=5). Biofilm formation (n=3) to Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans was evaluated after 24h by CV assay, CFU, XTT and confocal microscopy. Statistics were performed by one-way Anova, Tukey's tests and Pearson's correlation analysis at a pre-set significance level of 5 %.

RESULTS

Raman mappings revealed coverage yield of 82 % for TiGS and ≥99 % for TiGD and TiGV. Both TiGD and TiGV presented FWHM>44cm^-1 and I_D/I_G ratio<0.12, indicating multiple graphene layers and occlusion of defects. The contact angle was significantly higher for TiGD and TiGV (110° and 117°) comparing to the Control (70°). The SFE was lower for TiGD (13.8mN/m) and TiGV (12.1mN/m) comparing to Control (38.3mN/m). TiGD was selected for biofilm assays and exhibited significant reduction in biofilm formation for all microorganisms compared to Control. There were statistical correlations between the high contact angle and low SFE of TiGD and decreased biofilm formation.

SIGNIFICANCE

TiGD presented high quality and coverage and decreased biofilm formation for all species. The increased hydrophobicity of graphene films was correlated with the decreased biofilm formation for various species.

Fungal prosthetic aortic valve endocarditis and endarteritis: An unusual cause of aortic root vegetations

Fungal endocarditis is a relatively rare occurrence with high morbidity and mortality. Patients may have an indolent and non-specific course requiring a high index of suspicion to make a diagnosis. Here, we present the case of a 33-year-old patient who presented with fevers and acute lower limb ischemia requiring a 4-compartment fasciotomy caused by septic emboli from Candida albicans endocarditis. The patient had a large vegetation in the ascending aorta associated with a mycotic aneurysm, which is an exceedingly rare location for a vegetation. We also review the literature and summarize the typical echocardiographic appearance and vegetation locations in fungal endocarditis.

Risk Factors and Outcomes of Endocarditis Due to Non-HACEK Gram-Negative Bacilli: Data from the Prospective Multicenter Italian Endocarditis Study Cohort

The objective of this study was to investigate predisposing factors and outcomes of infective endocarditis (IE) caused by non-HACEK Gram-negative bacilli (GNB) in a contemporary multicenter cohort. Patients with IE due to GNB, prospectively observed in 26 Italian centers from 2004 to 2011, were analyzed. Using a case-control design, each case was compared to three age- and sex-matched controls with IE due to other etiologies. Logistic regression was performed to identify risk factors for IE due to GNB. Factors associated with early and late mortality were assessed by Cox regression analysis. The study group comprised 58 patients with IE due to GNB. We found that Escherichia coli was the most common pathogen, followed by Pseudomonas aeruginosa and Klebsiella pneumoniae The genitourinary tract as a source of infection (odds ratio [OR], 13.59; 95% confidence interval [CI], 4.63 to 39.93; P < 0.001), immunosuppression (OR, 5.16; 95% CI, 1.60 to 16.24; P = 0.006), and the presence of a cardiac implantable electronic device (CIED) (OR, 3.57; 95% CI, 1.55 to 8.20; P = 0.003) were factors independently associated with IE due to GNB. In-hospital mortality was 13.8%, and mortality rose to 30.6% at 1 year. A multidrug-resistant (MDR) etiology was associated with in-hospital mortality (hazard ratio [HR], 21.849; 95% CI, 2.672 to 178.683; P = 0.004) and 1-year mortality (HR, 4.408; 95% CI, 1.581 to 12.287; P = 0.005). We conclude that the presence of a genitourinary focus, immunosuppressive therapy, and an indwelling CIED are factors associated with IE due to GNB. MDR etiology is the major determinant of in-hospital and long-term mortality.