Intravascular Device Infections

Difficult-to-Treat Pathogens: A Review on the Management of Multidrug-Resistant Staphylococcus epidermidis

Multidrug-resistant Staphylococcus epidermidis (MDRSE) is responsible for difficult-to-treat infections in humans and hospital-acquired-infections. This review discusses the epidemiology, microbiology, diagnosis, and treatment of MDRSE infection and identifies knowledge gaps. By using the search term "pan resistant Staphylococcus epidermidis" OR "multi-drug resistant Staphylococcus epidermidis" OR "multidrug-resistant lineages of Staphylococcus epidermidis", a total of 64 records have been identified from various previously published studies. The proportion of methicillin resistance in S. epidermidis has been reported to be as high as 92%. Several studies across the world have aimed to detect the main phylogenetic lineages and antibiotically resistant genes through culture, mass spectrometry, and genomic analysis. Molecular biology tools are now available for the identification of S. epidermidis and its drug resistance mechanisms, especially in blood cultures. However, understanding the distinction between a simple colonization and a bloodstream infection (BSI) caused by S. epidermidis is still a challenge for clinicians. Some important parameters to keep in mind are the number of positive samples, the symptoms and signs of the patient, the comorbidities of the patient, the presence of central venous catheter (CVC) or other medical device, and the resistance phenotype of the organism. The agent of choice for empiric parenteral therapy is vancomycin. Other treatment options, depending on different clinical settings, may include teicoplanin, daptomycin, oxazolidinones, long-acting lipoglycopeptides, and ceftaroline. For patients with S. epidermidis infections associated with the presence of an indwelling device, assessment regarding whether the device warrants removal is an important component of management. This study provides an overview of the MDRSE infection. Further studies are needed to explore and establish the most correct form of management of this infection.

Evaluation of infections associated with implantable cardiac electronic devices: 10 years of experience in a single center

PURPOSE

Cardiac implantable electronic device (CIED) is used increasingly in recent years. In this study, it is aimed to evaluate the frequency of CIED-associated infections in the cardiology clinic of our hospital in the last 10 years, the causative microorganisms by determining their risk factors and clinical characteristics.

MATERIALS AND METHODS

225 patients who underwent CIED implantation in our hospital's cardiology clinic between March 2009 and December 2019 were retrospectively identified. The patients were grouped as with and without CIED-associated infection.

RESULTS

In a period of approximately 10 years, the rate of CIED infection was determined as 4.8%. 9 of the patients (81.8%) had CIED infection after the first implantation, and 2 of the patients (18.2%) after replacement. When the groups with and without CIED infection were compared; there was no significant difference in the group with CIED infection compared to the control group in terms of age, gender, type of the device inserted and the way of placing the device (implantation/replacement). Comparing risk factors between CIED infection and control group, there is no significant difference in terms of diabetes mellitus (DM), congestive heart failure, renal failure, hypertension, dyslipidemia, malignancy, immunosuppression. The use of anticoagulation was found statistically significant.

CONCLUSIONS

CIED infections occur clinically with increased morbidity and mortality due to factors related to the patient and/or the type of device implanted. Knowing the patient's comorbid conditions well and taking precautions before CIED implantation can contribute to the reduction of the CIED infections.

A Review of Cardiac Implantable Electronic Device Infections for the Practicing Electrophysiologist

Cardiovascular implantable electronic device (CIED) infections are morbid, costly, and difficult to manage. This review explores the pathophysiology, diagnosis, and management of CIED infections. Diagnostic accuracy has been improved through increased awareness and improved imaging strategies. Pocket or bloodstream infection with virulent organisms often requires complete system extraction. Emerging prophylactic interventions and novel devices have expanded preventative strategies and options for re-implantation. A clear and nuanced understanding of CIED infection is important to the practicing electrophysiologist.

Clinical Features and Outcome of Infective Endocarditis in a University Hospital in Romania

Background and Objectives: Characterization of patients with endocarditis regarding demographic, clinical, biological and imagistic data, blood culture results and possible correlation between different etiologic factors and host status characteristics. Material and methods: This is a retrospective observational descriptive study conducted on patients older than 18 years admitted in the past 10 years, in the Cardiology Clinic of the Clinical County Emergency Hospital Oradea Romania, with clinical suspicion of bacterial endocarditis. Demographic data, clinical, paraclinical investigations and outcome were registered and analyzed. Results: 92 patients with definite infective endocarditis (IE) according to modified Duke criteria were included. The mean age of patients was 63.80 ± 13.45 years. A percent of 32.6% had health care associated invasive procedure performed in the 6 months before diagnosis of endocarditis. Charlson's comorbidity index number was 3.53 ± 2.029. Most common clinical symptoms and signs were: shortness of breath, cardiac murmur, fever. Sixty-six patients had native valve endocarditis, 26 patients had prosthetic valve endocarditis and one patient was with congenital heart disease. Blood cultures were positive in 61 patients. Among positive culture patient's staphylococcus group was the most frequently involved: Staphylococcus aureus (19.6%) and coagulase negative Staphylococcus (18.5%). Most frequent complications were heart failure, acute renal failure and embolic events. Conclusions: Staphylococcus aureus IE was associated with the presence of large vegetations, prosthetic valve endocarditis and intracardiac abscess. Coagulase negative Staphylococcus (CoNS) infection was associated with prosthetic valve dysfunction. Streptococcus gallolyticus etiology correlated with ischemic embolic stroke and the presence of large vegetations. Cardiovascular surgery was recommended in 67.4% of patients but was performed only on half of them. In hospital death occurred in 33.7% of patients and independent predictors of mortality were congestive heart failure and septic shock.

Early abdominal aortic graft infection due to Propionibacterium acnes: a case report and review of the literature

Propionibacterium acnes is a member of the human microbiota that has been recently associated with late-onset infections of indwelling devices, especially shoulder prosthesis. Aortic graft infection are rare events with significant morbidity and mortality. Here, we describe the case of an abdominal aortic graft infection due to P. acnes with an unusual early onset. A review of the recent English language literature has been added.

Left Ventricular Assist Device Salvage with Omental Flap

A large number of people are affected with heart failure annually and require left ventricular assist device placement as a bridge to heart transplant or as destination therapy. When these devices become infected, it is a challenge to eradicate the infection. Failure ultimately results in a significant morbidity and mortality. Source control along with debridement and antibiotics can eradicate the infection of the patient, but many times there is a large defect that needs soft-tissue coverage. Many options for soft-tissue coverage have been suggested, but omentum may be an excellent choice due to its vascularity, bulk, and immunological properties. In this case report, the omental flap is employed for salvage of the left ventricular assist device with excellent results.

Staphylococcal biofilms: quest for the magic bullet

The biofilm phenotype has been recognized only relatively recently in medical history but it has rapidly become clear that the development of many, if not the majority of bacterial infections depends upon the formation of a biofilm. Medical device-related infections are one of the clearest examples of biofilm-dependent infections. Bacteria proficiently adhere to and establish biofilms on synthetic surfaces, and to date, no material has proven to completely preclude bacterial adherence. Any inserted device can be colonized but intravenous catheters, due to their widespread use, are the most commonly colonized devices. As many as half a million catheter-related infections occur each year in the United States and the staphylococci, in particular, Staphylococcus aureus and Staphylococcus epidermidis, are the leading cause. Biofilms exhibit tolerance to biocides, chemotherapeutic agents, and host-immune defenses and subsequently, biofilm-associated infections are extremely difficult to treat, frequently chronic, and often recurrent, making them a confounding clinical problem. Development of an effective strategy for preventing and/or treating these infections is of paramount importance and consequently, the search for novel approaches to target the biofilm phenotype has exploded in recent years. Because the biofilm phenotype is complex, targets for antibiofilm approaches are numerous and this line of research is significantly expanding our knowledge about the biofilm mode of growth and its role in disease. This review highlights a number of antibiofilm approaches that are currently under investigation as novel interventions for staphylococcal infections.

Epidemiology and prognosis of coagulase-negative staphylococcal endocarditis: impact of vancomycin minimum inhibitory concentration

This study describes coagulase-negative staphylococcal (CoNS) infective endocarditis (IE) epidemiology at our institution, the antibiotic susceptibility profile, and the influence of vancomycin minimum inhibitory concentration (MIC) on patient outcomes. One hundred and three adults with definite IE admitted to an 850-bed tertiary care hospital in Barcelona from 1995-2008 were prospectively included in the cohort. We observed that CoNS IE was an important cause of community-acquired and healthcare-associated IE; one-third of patients involved native valves. Staphylococcus epidermidis was the most frequent species, methicillin-resistant in 52% of patients. CoNS frozen isolates were available in 88 patients. Vancomycin MICs of 2.0 μg/mL were common; almost all cases were found among S. epidermidis isolates and did not increase over time. Eighty-five patients were treated either with cloxacillin or vancomycin: 38 patients (Group 1) were treated with cloxacillin, and 47 received vancomycin; of these 47, 27 had CoNS isolates with a vancomycin MIC <2.0 μg/mL (Group 2), 20 had isolates with a vancomycin MIC ≥ 2.0 μg/mL (Group 3). One-year mortality was 21%, 48%, and 65% in Groups 1, 2, and 3, respectively (P = 0.003). After adjusting for confounders and taking Group 2 as a reference, methicillin-susceptibility was associated with lower 1-year mortality (OR 0.12, 95% CI 0.02-0.55), and vancomycin MIC ≥ 2.0 μg/mL showed a trend to higher 1-year mortality (OR 3.7, 95% CI 0.9-15.2; P=0.069). Other independent variables associated with 1-year mortality were heart failure (OR 6.2, 95% CI 1.5-25.2) and pacemaker lead IE (OR 0.1, 95%CI 0.02-0.51). In conclusion, methicillin-resistant S.epidermidis was the leading cause of CoNS IE, and patients receiving vancomycin had higher mortality rates than those receiving cloxacillin; mortality was higher among patients having isolates with vancomycin MICs ≥ 2.0 μg/mL.

Propionibacterium acnes: from commensal to opportunistic biofilm-associated implant pathogen

Propionibacterium acnes is known primarily as a skin commensal. However, it can present as an opportunistic pathogen via bacterial seeding to cause invasive infections such as implant-associated infections. These infections have gained more attention due to improved diagnostic procedures, such as sonication of explanted foreign materials and prolonged cultivation time of up to 14 days for periprosthetic biopsy specimens, and improved molecular methods, such as broad-range 16S rRNA gene PCR. Implant-associated infections caused by P. acnes are most often described for shoulder prosthetic joint infections as well as cerebrovascular shunt infections, fibrosis of breast implants, and infections of cardiovascular devices. P. acnes causes disease through a number of virulence factors, such as biofilm formation. P. acnes is highly susceptible to a wide range of antibiotics, including beta-lactams, quinolones, clindamycin, and rifampin, although resistance to clindamycin is increasing. Treatment requires a combination of surgery and a prolonged antibiotic treatment regimen to successfully eliminate the remaining bacteria. Most authors suggest a course of 3 to 6 months of antibiotic treatment, including 2 to 6 weeks of intravenous treatment with a beta-lactam. While recently reported data showed a good efficacy of rifampin against P. acnes biofilms, prospective, randomized, controlled studies are needed to confirm evidence for combination treatment with rifampin, as has been performed for staphylococcal implant-associated infections.

Prevention of infections in cardiovascular implantable electronic devices beyond the antibiotic agent

The increase in incidence/prevalence of infections of implantable pacemakers and defibrillators (implantable cardioverter defibrillator, ICD) is outweighing that of the implanting procedures, mainly favored by the changes in patient profile. Despite the high impact on patient's outcome and related costs for healthcare systems, we lack specific evidence on the preventive measures with the exception of antibiotic prophylaxis. The aim of this study is to focus on common approaches to pacemaker/ICD implantation to identify the practical preventive strategies and choices that can (potentially) impact on the occurrence of this feared complication. After a brief introduction on clinical presentation, pathogenesis, and risk factors, we will present the results from a survey on the preventive strategies adopted by different operators from the 25 centers of the Emilia Romagna region in the northern Italy (4.4 million inhabitants). These data will provide the basis for reviewing available literature on this topic and identifying the gray areas. The last part of the article will cover the available evidence about pacemaker/ICD implantation, focusing on prophylaxis of pacemaker/ICD infection as a 'continuum' starting before the surgical procedure (from indications to patient preparation), which follows during (operator, room, and techniques) and after the procedure (patient and device follow-up). We will conclude by evaluating the relationship between adherence to the available evidence and the volume of procedures of the implanting centers or operators' experience according to the results of our survey.

Factors predictive of treatment failure in staphylococcal prosthetic vascular graft infections: a prospective observational cohort study: impact of rifampin

BACKGROUND

There exists considerable debate concerning management of prosthetic vascular graft infection (PVGI), especially in terms of antimicrobial treatment. This report studies factors associated with treatment failure in a cohort of patients with staphylococcal PVGI, along with the impact of rifampin (RIF).

METHODS

All data on patients with PVGI between 2006 and 2010 were reviewed. Cure was defined as the absence of evidence of infection during the entire post-treatment follow-up for a minimum of one year. Failure was defined as any other outcome.

RESULTS

84 patients (72 M/12 F, median age 64.5 ± 11 y) with diabetes mellitus (n = 25), obesity (n = 48), coronary artery disease (n = 48), renal failure (n = 24) or COPD (n = 22) were treated for PVGI (median follow-up was 470 ± 469 d). PVGI was primarily intracavitary (n = 47). Staphylococcus aureus (n = 65; including 17 methicillin-resistant S. aureus) and coagulase-negative Staphylocococcus (n = 22) were identified. Surgical treatment was performed in 71 patients. In univariate analysis, significant risk factors associated with failure were renal failure (p = 0.04), aortic aneurysm (p = 0.03), fever (p = 0.009), aneurysm disruption (p = 0.02), septic shock in the peri-operative period (p = 0.005) and antibiotic treatment containing RIF (p = 0.03). In multivariate analysis, 2 variables were independently associated with failure:septic shock [OR 4.98: CI 95% 1.45-16.99; p=0.01] and antibiotic containing rifampin [OR: 0.32: CI95% 0.10-0.96; p=0.04].

CONCLUSION

Results of the present study suggest that fever, septic shock and non-use of antibiotic treatment containing RIF are associated with poor outcome.

Multilocus Sequence Typing for Interpreting Blood Isolates of Staphylococcus epidermidis

Staphylococcus epidermidis is an important cause of nosocomial infection and bacteremia. It is also a common contaminant of blood cultures and, as a result, there is frequently uncertainty as to its diagnostic significance when recovered in the clinical laboratory. One molecular strategy that might be of value in clarifying the interpretation of S. epidermidis identified in blood culture is multilocus sequence typing. Here, we examined 100 isolates of this species (50 blood isolates representing true bacteremia, 25 likely contaminant isolates, and 25 skin isolates) and the ability of sequence typing to differentiate them. Three machine learning algorithms (classification regression tree, support vector machine, and nearest neighbor) were employed. Genetic variability was substantial between isolates, with 44 sequence types found in 100 isolates. Sequence types 2 and 5 were most commonly identified. However, among the classification algorithms we employed, none were effective, with CART and SVM both yielding only 73% diagnostic accuracy and nearest neighbor analysis yielding only 53% accuracy. Our data mirror previous studies examining the presence or absence of pathogenic genes in that the overlap between truly significant organisms and contaminants appears to prevent the use of MLST in the clarification of blood cultures recovering S. epidermidis.

An interesting septic embolism

Septic pulmonary embolism is a rare disease but mortality and morbidity of it is high. Septic pulmonary emboli comes from infected heart valves, thrombophlebitis, and pulmonary artery catheter or infected pacemaker wires as many sources [1,2]. In recent years, pacemaker is a common treatment of the bradiarrhythmia that is persisted in the etiology of septic embolism, its applications has started to pick up [3]. There is the growing number of patients with pacemaker, according to this the frequency of pacemaker lead infection and the number of patients at risk for right-sided endocarditis increase [4]. The patients don't have specific clinical and radiological features because of this it is very difficult to define, so the diagnosis is often delayed [5]. A detailed medical history, a detailed physical examination in diagnosis and evaluation of good additional imaging methods is very important. Early diagnosis and proper treatment, the implementation of the management, can provide good results.

Combined effect of linezolid and N-acetylcysteine against Staphylococcus epidermidis biofilms

INTRODUCTION

Staphylococcus epidermidis is an organism commonly associated with infections caused by biofilms. Biofilms are less sensible to antibiotics and therefore are more difficult to eradicate. Linezolid and N-acetylcysteine (NAC), have demonstrated to be active against gram-positive microorganisms. Therefore and since linezolid and NAC have different modes of action, the main objective of this work was to investigate the single and synergistic effect of linezolid and NAC against S. epidermidis biofilms.

METHODS

This work reports the in vitro effect of linezolid and NAC against S. epidermidis biofilms, treated with MIC (4mgml(-1)) and 10×MIC of NAC, and MIC (1μgml(-1)) and peak serum concentration (PS=18μgml(-1)) of linezolid alone and in combination. After exposure of S. epidermidis biofilms to linezolid and/or NAC for 24h, several biofilm parameters were evaluated, namely the number of cultivable cells [colony forming unit (CFU) enumeration], total biofilm biomass and cellular activity.

RESULTS

When tested alone, NAC at 10×MIC was the most effective agent against S. epidermidis biofilms. However, the combination linezolid (MIC)+NAC (10×MIC) showed a synergistic effect and was the most biocidal treatment tested, promoting a 5log reduction in the number of biofilm viable cells.

CONCLUSION

This combination seems to be a potential candidate to combat infections caused by S. epidermidis biofilms, namely as a catheter lock solution therapy.

The role of ionic interactions in the adherence of the Staphylococcus epidermidis adhesin SdrF to prosthetic material

Staphylococcus epidermidis infections are common complications of prosthetic device implantation. SdrF, a surface protein, appears to play a critical role in the initial colonization step by adhering to type I collagen and Dacron™. The role of ionic interactions in S. epidermidis adherence to prosthetic material was examined. SdrF was cloned and expressed in Lactococcus lactis. The effect of pH, cation concentration, and detergents on adherence to different types of plastic surfaces was assessed by crystal violet staining and bacterial cell counting. SdrF, in contrast with controls and other S. epidermidis surface proteins, bound to hydrophobic materials such as polystyrene. Binding was an ionic interaction and was affected by surface charge of the plastic, pH, and cation concentration. Adherence of the SdrF construct was increased to positively charged plastics and was reduced by increasing concentrations of Ca(2+) and Na(+). Binding was optimal at pH 7.4. Kinetic studies demonstrated that the SdrF B domain as well as one of the B subdomains was sufficient to mediate binding. The SdrF construct also bound more avidly to Goretex™ than the lacotococcal control. SdrF is a multifunctional protein that contributes to prosthetic devices infections by ionic, as well as specific receptor-ligand interactions.

Mycobacterium fortuitum causing infection of a biventricular pacemaker/implantable cardioverter defibrillator

Increased utilization of cardiovascular implantable electronic devices (CIED) has seen a corresponding rise in related infections. Non-tuberculosis mycobacteria (NTM) are rarely the cause. Treatment involves susceptibilities, antimicrobials, and device removal. This study presents a patient who underwent a biventricular implantable cardioverter defibrillator upgrade with a multi-drug resistant Mycobacterium fortuitum located at the pocket site and a lead infection.

Evaluation of an institutional guideline for the treatment of cerebrospinal fluid shunt-associated infections

BACKGROUND

Cerebrospinal fluid (CSF) shunt-associated infection is one of the most frequent complications of CSF shunt surgery. We evaluated our institutional guideline for the treatment of shunt-associated infections.

METHODS

We retrospectively analysed all 92 episodes of shunt-associated infections in 78 patients treated in our institution from 2002 to 2008. All patients underwent urgent surgery, i.e. removal of the complete shunt hardware or externalisation of the distal tubing in cases with an infection restricted to the distal shunt (10 %), placement of an external ventricular drainage as necessary and antibiotic therapy. Standard empirical first-line antibiotic treatment consisted of a combination of flucloxacillin and cefuroxime.

RESULTS

We observed 38 % early (<1 month after shunt surgery) and 20 % late infections (> 1 year after shunt placement). Coagulase-negative staphylococci (CoNS) were isolated in 38 %. In 38 % no pathogens could be isolated. Of cases with a first shunt infection, 58 % were initially treated with flucloxacillin/cefuroxime. Only 53 % of all infections were treated successfully with the first course of antibiotics. Only 51 % of bacterial isolates were sensitive to empirical first-line antibiotics. Twenty percent of infections caused by sensitive bacterial isolates nevertheless required second-line antibiotic therapy.

CONCLUSIONS

Urgent surgery for shunt removal and antibiotic therapy will usually cure a shunt-associated infection. The choice of antibiotics should reflect the spectrum of pathogens seen at one's institution, paying particular attention to the role of CoNS isolates, and in vitro sensitivity testing results.

Aortic graft infection as a cause of multiple brain infarcts

Brain embolism of cardiac origin is common in clinical practice. However, embolic brain infarcts due to aortic graft infection are very rare. We present a case of a 53-year-old woman with multiple brain infarcts, following an infection of ascending aortic graft. She was presented with fever and acute onset neurological deficit, and she had a previous history of replacement of ascending aorta with a prosthetic graft, because of aortic aneurysm 2 years before her admission. The patient had positive blood cultures and echocardiographic evidence of vegetation in the graft aortic joint, nearby the aortic valves. Despite the severe clinical condition and the poor prognosis, because of the coexistence of cardioembolism and aortic graft infection, our patient had a good outcome with conservative treatment and she will be considered for surgical graft replacement after her full recovery.

Permanent pacemaker and implantable cardioverter defibrillator infections: seven years of diagnostic and therapeutic experience of a single center

BACKGROUND

Increasing evidence-based indications for the implantation of permanent pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) have led to an increase in the rate of device infections. The aim of the present study was to evaluate infection frequency, clinical characteristics, risk factors, and microbiologic and therapeutic features in patients with PM/ICD infections.

HYPOTHESIS

Clinical and demographic characteristics of the patients can affect the PM/ICD infections.

METHODS

The PM/ICD infection group consisted of 57 patients diagnosed and treated with PM/ICD infections in our hospital. The control group in this case-control study consisted of 833 patients in whom a PM or ICD had been implanted and no infections were noted.

RESULTS

Patients with PM/ICD infections (median age 65 years; range, 18-104 years) were older than those without PM/ICD infections (median age 58 years; range, 18-86 years; P = 0.005). The percentage of generator replacement was higher in the PM/ICD infection group compared with the control group (16% vs 8%, P = 0.003). Independent predictors of PM/ICD infections were advanced age (>60 years; odds ratio [OR]: 2.5, 95% confidence interval [CI]: 1.2-4.0, P = 0.021) and device revision (OR: 3.8, 95% CI: 1.5-5.5, P = 0.002). Primary antibiotic prophylaxis during the procedure reduced the risk for PM/ICD infection (OR: 0.5, 95% CI: 0.4-0.8, P = 0.011).

CONCLUSIONS

PM/ICD infections occur in a significant number of patients. It is important to be aware of the risk factors for PM/ICD infections so that patients with an increased risk can be identified and preventive measures can be implemented.

Prevention of early vascular graft infection using regional antibiotic release

BACKGROUND

Infections after prosthetic replacement of the aorta remain a serious and life-threatening complication. The only appropriate treatment is the surgical removal of the infected prosthesis. Accordingly, there is a need for new procedures to prevent the infection of vascular prostheses. This in vitro experiment investigated the effect of the pretreatment of vascular prostheses with antibiotics (daptomycin or baneocin) and the effect of antibiotics combined with fibrin sealant as possible prophylaxis of perioperative graft infection.

METHODS

Untreated prostheses served as controls. Pretreated prostheses of double woven velour vascular grafts were contaminated with Staphylococcus epidermidis, and colony-forming units were counted each day (CFU/mL).

RESULTS

The period of sterility differed significantly as a function of the pretreatment. Uncoated prostheses were immediately non-sterile and exhibited 2.63 ± 0.61 × 10(5) CFU/mL. Baneocin pretreatment resulted in sterility for 1.7 ± 0.6 (95% confidence interval (CI) 1.0-2.4) d before we detected 2.14 ± 0.57 × 10(5) CFU/mL on the prostheses. Pretreatment with daptomycin yielded 2.9 ± 0.4 (CI 2.6-3.2) and fibrin sealant/baneocin compound yielded 3.1 ± 0.3 (CI 2.9-3.3) d of sterility, after which 1.81 ± 0.86 × 10(5) CFU/mL and 1.04 ± 0.77 × 10(5) CFU/mL were recorded. Finally, pretreatment with fibrin sealant/daptomycin led to sterility for 7.1 ± 0.3 (CI 6.9-7.3) d, after which 0.77 ± 0.60 × 10(5) CFU/mL were observed on the prostheses.

CONCLUSIONS

The risk of vascular graft infection is reduced by pretreating the prostheses with antibiotics. The antibiotic/fibrin compound exhibited an effect of delayed antibiotic release. Vascular prostheses should therefore be pretreated with antibiotic solution to reduce bacterial adhesion. This procedure might be an effective prophylaxis for perioperative vascular graft infection and provides suitable protection for the prosthetic material.

Novel synergistic antibiofilm combinations for salvage of infected catheters

Biofilms on catheters are responsible for catheter-related bloodstream infections (CRBSIs), which cause significant mortality and morbidity. Antimicrobial catheter-lock solutions may salvage precious catheters by eradicating biofilms. Staphylococcus epidermidis and Candida albicans are frequently isolated organisms in CRBSIs. We evaluated N-acetylcysteine (NAC), EDTA, ethanol and talactoferrin (TLF) individually and in combination with antibiotics against biofilms of S. epidermidis and C. albicans to identify effective catheter-lock solutions. Minimum biofilm-eradication concentrations causing 50% inhibition (MBEC(50)) for EDTA, NAC, ethanol and TLF were determined against biofilms of S. epidermidis and C. albicans formed on 96-well microtitre plates. Biomass, mean thickness and viability of S. epidermidis and C. albicans biofilms were evaluated after exposure to MBEC(50) concentrations of EDTA, NAC, ethanol and TLF. Antimicrobial combinations of EDTA, NAC, ethanol and TLF with nafcillin, vancomycin, fluconazole and amphotericin B were evaluated systematically for synergy using combination indices (CIs). EDTA, NAC, ethanol and TLF significantly reduced biofilm biomass and mean thickness (P<0.05, one-way ANOVA) of monomicrobial and polymicrobial biofilms as evaluated by confocal microscopy. CIs evaluated at equipotency ratios, and 50, 75 and 90 % effects, showed that EDTA, NAC, ethanol and TLF were synergistic (CI <1) with antibiotics (with few exceptions) against biofilms of S. epidermidis and C. albicans. EDTA, NAC, ethanol and TLF inhibit monomicrobial and polymicrobial biofilms of neonatal strains of S. epidermidis and C. albicans, and are synergistic with antibiotics. Catheter-lock solutions of EDTA, NAC and ethanol alone or in combination with antibiotics may be used to salvage infected catheters, which will directly impact on patient morbidity and health-care costs.

SdrF, a Staphylococcus epidermidis surface protein, contributes to the initiation of ventricular assist device driveline-related infections

Staphylococcus epidermidis remains the predominant pathogen in prosthetic-device infections. Ventricular assist devices, a recently developed form of therapy for end-stage congestive heart failure, have had considerable success. However, infections, most often caused by Staphylococcus epidermidis, have limited their long-term use. The transcutaneous driveline entry site acts as a potential portal of entry for bacteria, allowing development of either localized or systemic infections. A novel in vitro binding assay using explanted drivelines obtained from patients undergoing transplantation and a heterologous lactococcal system of surface protein expression were used to identify S. epidermidis surface components involved in the pathogenesis of driveline infections. Of the four components tested, SdrF, SdrG, PIA, and GehD, SdrF was identified as the primary ligand. SdrF adherence was mediated via its B domain attaching to host collagen deposited on the surface of the driveline. Antibodies directed against SdrF reduced adherence of S. epidermidis to the drivelines. SdrF was also found to adhere with high affinity to Dacron, the hydrophobic polymeric outer surface of drivelines. Solid phase binding assays showed that SdrF was also able to adhere to other hydrophobic artificial materials such as polystyrene. A murine model of infection was developed and used to test the role of SdrF during in vivo driveline infection. SdrF alone was able to mediate bacterial adherence to implanted drivelines. Anti-SdrF antibodies reduced S. epidermidis colonization of implanted drivelines. SdrF appears to play a key role in the initiation of ventricular assist device driveline infections caused by S. epidermidis. This pluripotential adherence capacity provides a potential pathway to infection with SdrF-positive commensal staphylococci first adhering to the external Dacron-coated driveline at the transcutaneous entry site, then spreading along the collagen-coated internal portion of the driveline to establish a localized infection. This capacity may also have relevance for other prosthetic device–related infections.

This study investigates the manner in which heart pumps become infected. Infections involving the driveline, the cord that connects the pump to its external power source, are a major complication of implantation of these devices. In this study, we examined why Staphylococcus epidermidis, a bacteria that is commonly found on the skin, is responsible for the majority of these infections. The ability of different surface molecules of S. epidermidis to attach to drivelines removed from patients undergoing transplantation was tested. SdrF, one of the S. epidermidis surface proteins studied, showed the highest adherence to the drivelines. This binding appeared to involve attachment of the B subunit of SdrF to collagen, a molecule that coats the driveline following implantation. SdrF also mediated attachment to the non-implanted Dacron material that is used to coat the drivelines. A mouse driveline infection model also demonstrated that SdrF was sufficient to initiate a driveline infection. Driveline infection can therefore be hypothesized to occur via: 1) skin colonization by S. epidermidis; 2) adherence of SdrF-positive S. epidermidis to the Dacron surface at the skin entry site; 3) migration of bacteria along the driveline; 4) adherence to the internal driveline via the collagen coating its surface; and 5) initiation of infection.

Infection after ICD implantation: operating room versus cardiac catheterisation laboratory

BACKGROUND/OBJECTIVES

Since the insertion of an implantable cardioverter-defibrillator (ICD) has become technically comparable to pacemaker implantation, these procedures are increasingly being performed in a cardiac catheterisation laboratory (CCL) instead of the operating room (OR). This study aims to describe the relationship between incidence of ICD infection and procedure setting and to describe the characteristics of ICD infection.

METHODS

A retrospective study was performed of first ICD implantation in 677 patients admitted to our hospital between 1996 and 2006. Implantations were performed in the OR until 2003, after 2003 they were carried out in the CCL. The follow-up was censored at one year after implantation. ICD infections were defined as pocket infection or ICD-related endocarditis and a descriptive analysis was performed.

RESULTS

Cardiothoracic surgeons implanted 366 ICDs in the OR Electrophysiologists performed 301 implantations in the CCL. Pulse generators were inserted using a pectoral approach with transvenous lead systems. We identified seven ICD infections (incidence rate 1.2/100 person-years), three of which had been implanted in the OR and four in the CCL.

CONCLUSION

In this single-centre study no difference in the incidence of ICD infection was observed between implantation in OR and CCL. However, a larger study will be necessary to rule out a relationship with certainty. (Neth Heart J 2009;17:95-100.).

Complications in patients with ventricular assist devices

Heart failure affects more than 5 million people in the United States. The treatments of this disease include medical therapy, heart transplantation, and the implantation of ventricular assist devices. These devices are used in patients who are no longer responsive to conservative medical treatment, who are not candidates for a heart transplantation (destination therapy), who are awaiting a heart transplantation (bridge to transplantation), and who have acute heart failure and whose myocardial function is expected to return to normal (bridge to recovery). Although this therapy improves the mortality and quality of life among patients with heart failure, the devices also carry risk of multiple complications. This article discusses the acute and long-term complications of ventricular assist devices.

Antimicrobial activity of the ornamental species Salvia corrugata, a potential new crop for extractive purposes

As a part of our search for biologically active compounds from cultivated Salvia spp. we investigated Salvia corrugata Vahl. The activity of two isolated icetaxane diterpene quinones, fruticuline A and demethylfruticuline A, was assessed against 46 bacterial pathogens, mostly resistant to several primary antibiotics. The MIC for all the inhibited Gram-positive pathogens tested showed a very narrow distribution and ranged from 32 to 64 mg/L, regardless of their resistance patterns to other antibiotics. Demethylfruticuline A was shown to be highly bactericidal (>3 log(10) CFU decrease within 24 h) against Staphylococcus aureus and S. epidermidis and bacteriostatic against Enterococcus faecalis and E. faecium. Fruticuline A manifested bacteriostatic activity against all tested strains. S. corrugata can be viewed as an interesting source for these diterpenes, which, if well tolerated in vivo, may represent new medical agents useful for the treatment of serious infections caused by resistant Gram-positive pathogens.

Percutaneous stent placement in children weighing less than 10 kilograms

The objectives of this study were to evaluate the safety, efficacy, and outcomes of palliative percutaneous stent placement in infants with congenital heart disease (CHD). There is interest in improving outcomes of infants with CHD through interventional/surgical collaboration. Small, high-risk patients may benefit from delayed open operations, and endovascular stents may provide a means to defer surgery to more advantageous times in select infants. Patients weighing < or =10 kg in whom stent placement was attempted during 2003-2006 were identified. Diagnoses, indications, angiographic and hemodynamic data, complications, and outcomes were reviewed. Seventeen stents were successfully placed in 15 patients. The mean age was 10.21 months; the mean weight was 6.08 kg. Indications were branch pulmonary artery stenosis, coarctation, total anomalous pulmonary venous return with obstructed venous egress, right ventricle-pulmonary artery conduit, and shunt stenosis. Premounted Palmaz Genesis and Driver Mx stents were used. Average vessel diameter increased from 3.65 to 6.72 mm (p < 0.001). The pressure gradient fell from 24 to 15 mm Hg (p < 0.01). Two stents migrated. One was recaptured and implanted at the target site and one implanted away from the target site. None needed surgical intervention. Mean follow-up was 270 days. Five patients have had additional surgery; seven patients underwent 10 additional stent dilations. There was no procedural-related mortality. Five patients (33%) died during the follow-up period, none attributable to the stent placement. We conclude that stent placement can be successfully accomplished in select, small, high-risk patients. A collaborative interventional/surgical paradigm is important to ensure that the risk-benefit ratio is properly evaluated during the patient selection.

[Non-valvular cardiac devices endocarditis]

The risk of infective endocarditis on pacemaker or ICD is not negligible and has increased in recent years. Several host-related, procedure-related, or device-related risk factors have been recognized. Owing to its potential severity, the possibility of infective endocarditis should be envisaged in patients with repeated pulmonary infections or documented bacteremia and transesophageal echocardiography should then be used. The most common germs causing pacemaker endocarditis are staphylococci. Treatment requires prolonged antibiotic therapy and retrieval of the pacemaker and leads.

The diagnosis and treatment of cardiac ion channelopathies: Congenital long QT syndrome and Brugada syndrome

Sudden cardiac death in young adults can be due to a range of conditions including coronary disease, hypertrophic or dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. Although each of these disorders has typical pathologic findings, some victims display no overt abnormalities and are presumed to have died from a primary cardiac arrhythmia. Increasingly, these malignant arrhythmias have been demonstrated to be due to mutations in ion channels. In this review we focus on the two most common of these disorders, termed ion channelopathies, namely congenital long QT syndrome and Brugada syndrome.

Infections associated with long-term prosthetic devices

The extensive and ever-increasing use of long-term prosthetic devices has improved quality of life and survival for many patients. Prosthetic device-related infection occurs infrequently but is associated with significant morbidity and mortality. Management is challenging, often requiring prolonged antimicrobial therapy and surgical intervention. Better understanding of the interaction between microorganisms, devices, and the host should improve the ability to manage device-related infections. This article reviews recent advances in the diagnosis and treatment of infections associated with indwelling medical devices, highlighting those associated with prosthetic joints, cerebrospinal fluid shunts, and prosthetic heart valves.

Rapid identification and specific quantification of Staphylococcus epidermidis by 5' nuclease real-time polymerase chain reaction with a minor groove binder probe

A species-specific quantitative detection method involving 5' nuclease real-time polymerase chain reaction using a minor groove binder probe that was designed from the sodA gene was developed for Staphylococcus epidermidis. This method distinguished S. epidermidis from other staphylococci and specifically quantified the bacterium. This study shows that the method is useful for the identification and quantitative detection of S. epidermidis.