Usefulness of sonication in the microbiological diagnosis of cardiovascular implantable electronic device infections: systematic review, meta-analysis and meta-regression

BACKGROUND

Multiple studies have demonstrated the utility of sonication to improve culture yield in patients with cardiovascular implantable electronic device (CIED) infections.

OBJECTIVE

To analyze the usefulness of sonication in the microbiological diagnosis of CIED infections in comparison with traditional cultures.

METHODS

Systematic database searches were performed to identify studies that provided enough data concerning both sensitivity and specificity of traditional (non-sonicated) and sonicated cultures from CIED samples. The diagnostic accuracy measures were obtained by three different statistical approaches: (i) The univariate model; (ii) The bivariate random; and (iii) The Bayesian bivariate hierarchical model. Heterogeneity was assessed using meta-regression.

FINDINGS

Nine studies met the criteria for inclusion in the meta-analysis (1684 cultures). The summary estimates of sensitivity were higher for sonicated cultures (0.756) in comparison with non-sonicated cultures (0.446). On meta-regression, sonication of CIEDs significantly increased the sensitivity (p = 0.001) as well as the rates of false positive results (p = 0.003). The final model also showed that the studies that used a threshold for positivity were associated with lower rates of false positive results (p < 0.001).

INTERPRETATION

Our results suggest that sonication improves the microbiological diagnosis of CIED infections in comparison with traditional cultures, but a standardization of processes is necessary.

Clinical impact of capsulectomy during cardiac implantable electronic device generator replacement: a prospective randomized trial

BACKGROUND

The avascular capsule around the generator of the cardiac implantable electronic device (CIED) could be susceptible to bacterial colonization and source of infection. Capsulectomy during CIED generator replacement may be beneficial in preventing device infection, but there is a lack of evidence.

METHODS

This prospective randomized trial, conducted from December 2013 to December 2019, included 195 patients divided equally into two groups. In the intervention group (n = 97), capsule removal was performed on the floor of the pocket, while it was not performed in the control group (n = 98). In both groups, swab culture was performed in the pocket. The primary outcome was the occurrence of device infection requiring pocket revision.

RESULTS

A total of 195 patients were included (mean age 70.2 ± 13.6 years, 55.4% women), with an average follow-up period of 54.3 ± 28.9 months. Among 182 patients undergoing microbiological cultures of pockets, 19 (10.4%) were confirmed positive, and Staphylococcus species were identified most frequently. The primary outcome occurred in 4 (2.1%), and there was no significant difference between the two groups (3.1% vs. 1.0%, p = 0.606). Hematoma has occurred in 10 patients (3.1% vs. 7.1%, p = 0.338), one of them required wound revision. In multivariable analysis, the occurrence of hematoma was the only independent risk factor associated with device infection (HR 13.6, 95% CI 1.02-181.15, p = 0.048).

CONCLUSIONS

In this long-term prospective study, capsulectomy during the replacement of the generator did not reduce the incidence of device infection. There was no association between bacterial colonization in the capsule around the generator and CIED infection.

Do barrier dressings reduce cardiac implantable device infection: Protocol for a randomized controlled trial (BARRIER-PROTECT)

Background

Cardiac implantable electronic device (CIED) procedures can be associated with serious complications, including infection with significant mortality and morbidity, necessitating removal of the device and prolonged hospitalization. One potential pathophysiological mechanism is pocket contamination at the time of device implantation. Therefore, steps taken to prevent contamination at this stage can potentially reduce CIED infections.The barrier dressing, an adhesive material applied to the skin, has the potential to reduce the colonization of the surgical site with host flora that can predispose to infection. There are a limited number of randomized prospective studies on barrier dressing use during various surgeries, but it has never been systematically studied in CIED implantation.

Objectives

Do Barrier Dressings Reduce Cardiac Implantable Device Infection? (BARRIER-PROTECT trial; NCT04591366) is a single-centre, prospective, double-armed, single-blinded, randomized controlled trial designed to evaluate the use of an intra-operative adhesive barrier dressing to reduce the risk of end-of-procedure pocket swab positivity. We hypothesize that adhesive draping during implant procedures will reduce the risk of contamination from the skin flora. Also, we aim to investigate if the end-of-procedure pocket swab culture positivity can be used as a potential surrogate marker of CIED infection.

Methods and Design

Patients undergoing a second or later procedure on the same device pocket (pulse generator change, lead/pocket revision or upgrade) will be enrolled. Eligible and consenting patients will be equally randomized to the use of barrier dressing or not using an automated web-based system. Patients, but not the operator, will be blinded to the arm. The person performing the pocket swabs will also be blinded. The primary endpoint is the end-of-procedure pocket swab culture positivity. The main secondary endpoint is the CIED infection rate.

Discussion

This is the first randomized controlled trial to assess the effectiveness of using a barrier adhesive draping on reducing the end-of-procedure pocket swab culture positivity. In this study, we are exploring a low-cost intervention that may significantly reduce CIED infection. Also, having a valid surrogate marker for CIED infection at the time of implant will facilitate design of future clinical trials.

[Pacemaker infection in fragile patients]

Complications associated with cardiac implantable electric devices (CIED) are manifold. They include lead dislocation, twiddler's syndrome, device malfunction, haematoma formation and infection. Infections can be divided into acute, subacute and late infections. Both the time of onset and the route of infection play a crucial role. The consequences of a CIED infection are devastating. The most modern treatment methods include the removal of all implanted implants. If complete removal is not followed in the event of infection, there is a high rate of infection recurrence. Open thoracic surgery to remove infected CIED hardware has been replaced by percutaneous lead extraction procedures. Lead extraction requires specialised equipment and expertise and may not be readily available or feasible for some patients. Each extraction procedure is associated with a small risk of potentially fatal complications (e.g. cardiac avulsion, vascular avulsion, haemothorax and cardiac tamponade). For these reasons, the performance of such procedures should be limited to centres with adequate equipment and experience. Successful salvage of CIED systems with in situ sterilisation of contaminated hardware has been reported. In our case, we report the successful salvage of an exposed generator in a frail patient treated more than 5 years after the last generator replacement.

Early, Delayed and Late Cardiac Implantable Electronic Device Infections: Do the Timing of Onset and Pathogens Matter?

Infections involving cardiac implantable electronic devices (CIEDs) occur at different times after device-related procedures. The aim of this study was to investigate the timing of onset and factors influencing the occurrence of all types of CIED infections to identify the type of pathogen and to examine the long-term survival of patients with all types of CIED infections. We performed a post hoc analysis of the clinical data from 3344 patients who underwent transvenous lead extraction (TLE) at a single high-volume center between 2006 and 2020, including a group of 890 patients with CIED infections. The occurrence of pocket infection (PI), lead-related infective endocarditis (LRIE) and PI coexisting with LRIE (PI + LRIE) was assessed at the following time intervals: 0−12 months, 13−36 months and > 36 months since last CIED-related procedure. In the study group, there were 274 (30.79%) early infections, 266 (29.89%) delayed infections and 350 (39.32%) late infections. Pocket infection was the most common early complication (97; 39.43%), while LRIE was predominant over 36 months from the last CIED procedure (172; 54.09%). The most common early infections were PIs that were associated with the preceding CIED-related procedure. Late LRIE was most likely to occur in patients with intracardiac lead abrasion. The probability of early versus late LRIE was higher in patients with CoNS cultures. The timing of infection onset irrespective of its type does not affect long-term survival after transvenous lead extraction. The majority of infectious complications (69%) occur more than 12 months after the last CIED-related procedure. Early infections are probably associated with pocket contamination during CIED-related procedure, while delayed and late systemic infections are related to other lead-dependent factors (especially to intracardiac lead abrasion). Time to LRIE onset is associated with pathogen type. The timing of symptom onset does not affect long-term survival after TLE.

Risk Stratifying and Prognostic Analysis of Subclinical Cardiac Implantable Electronic Devices Infection: Insight From Traditional Bacterial Culture

Background

Subclinical infection of cardiac implantable electronic devices (CIEDs) is a common condition and increases the risk of clinical infection. However, there are limited studies focused on risk stratifying and prognostic analysis of subclinical CIED infection.

Methods and Results

Data from 418 consecutive patients undergoing CIED replacement or upgrade between January 2011 and December 2019 were used in the analysis. Among the patients included, 50 (12.0%) were detected as positive by bacterial culture of pocket tissues. The most frequently isolated bacteria were coagulase‐negative staphylococci (76.9%). Compared with the noninfection group, more patients in the subclinical infection group were taking immunosuppressive agents, received electrode replacement, or received CIED upgrade and temporary pacing. Patients in the subclinical infection group had a higher PADIT (Prevention of Arrhythmia Device Infection Trial) score. Univariable and multivariable logistic regression analysis found that use of immunosuppressive agents (odds ratio [OR], 6.95 [95% CI, 1.44–33.51]; P=0.02) and electrode replacement or CIED upgrade (OR, 6.73 [95% CI, 2.23–20.38]; P=0.001) were significantly associated with subclinical CIED infection. Meanwhile, compared with the low‐risk group, patients in the intermediate/high‐risk group had a higher risk of subclinical CIED infection (OR, 3.43 [95% CI, 1.58–7.41]; P=0.002). After a median follow‐up time of 36.5 months, the end points between the subclinical infection group and noninfection group were as follows: composite events (58.0% versus 41.8%, P=0.03), rehospitalization (54.0% versus 32.1%, P=0.002), cardiovascular rehospitalization (32.0% versus 13.9%, P=0.001), CIED infection (2.0% versus 0.5%, P=0.32), all‐cause mortality (28.0% versus 21.5%, P=0.30), and cardiovascular mortality (10.0% versus 7.6%, P=0.57).

Conclusions

Subclinical CIED infection was a common phenomenon. The PADIT score had significant value for stratifying patients at high risk of subclinical CIED infection. Subclinical CIED infection was associated with increased risks of composite events, rehospitalization, and cardiovascular rehospitalization.

Implantable Cardiac Device Infections Prevalence: Diagnostic and Therapeutic Implications

Background:  It has been demonstrated that the use of cardiac implanted electronic devices (CIED) improve mortality and survivability in a variety of patient populations. Nevertheless, CIED related infection is a serious complication characterized by a high rate of mortality and morbidity. Objectives: To evaluate the prevalence of CIED related infections, risk factors, clinical and demographic characteristics, causative organisms, and the management and outcome of patients presented in the Critical Care Department, Cairo University. Methods: A retrospective analysis was conducted in 1871 individuals who had been implanted with a cardiac device with a total number of devices of 1968 and 2270 procedures performed from January 2007 to December 2017. Results: 59 infectious episodes were identified with an estimated incidence of 2.99% of inserted devices and 2.6% of total procedures.  The infection rate was considerably higher in patients with multiple procedures than those who had a single procedure (9.27% vs. 1.18%; P<0.001). The individuals with a dual-chamber implantable cardiac defibrillator (ICD) and cardiac resynchronization therapy devices (CRTD) had the highest infection rate of 6.25% & 6.85%, respectively. The rate of pocket infection (PI) and CIED related endocarditis (CDE) was 1.54% & 1.06% of total devices respectively.  Numerous risk factors have been found; the most significant of those are diabetes mellitus, recurrent procedures, the device's complexity, and the existence of more than one lead. Gram-positive cocci were the most isolated organisms in all positive cultures (69.23%). Echocardiography revealed lead vegetations and valvular vegetations in 22 patients and 2 patients respectively.  In 53 cases (89.83%), the devices were removed; in 41 cases, the entire system was removed; and in 12 cases, only the generator was removed. The mortality rate was found to be 10.17%, having a considerably higher prevalence in CDE individuals than in pocket infection individuals (20.83% vs. 2.86%; P=0.025). Conclusion: In our center, while the rate of CIED implantation continues to increase, the incidence rate of CIED-related infection continues to decline. Until now, the infection burden associated with secondary intervention is still significantly high.  The management strategy of selection is to eliminate the entire system for patients presented with infection especially those with CDE. However, the mortality rate is still high.

Effect of fibrotic capsule debridement during generator replacement on cardiac implantable electronic device infection risk

BACKGROUND

Cardiovascular implantable electronic device (CIED) replacement is increasingly common. It has been proposed that capsule removal at the time of CIED replacement may reduce infection rates. In this study, we aimed to assess how pocket capsule removal impacted infection rates in patients undergoing CIED replacement.

METHODS

We retrospectively reviewed the medical records of patients who underwent CIED replacement from 2006 to 2016 at a single centre. We retrieved patient data, procedure details, and clinical outcomes. To evaluate the relationship between capsule removal and CIED infection, we used the Cox proportional hazard model, with adjustment for multiple variables.

RESULTS

During the study period, 773 patients underwent device replacement. Of these patients, 194 (25%) underwent capsule debridement during the replacement procedure. The mean patient age was 75 ± 15 years, and 281 (36.3%) were females. The replaced CIEDs included DDD pacemakers (32%), VDD pacemakers (15%), VVI/AAI pacemakers (13%), defibrillators (22%), and cardiac resynchronization therapy devices (CRT-D/P) (17%). During an average follow-up of 3.6 years, 42 (5%) patients experienced a CIED infection. Multivariate analysis revealed that patients who underwent capsule removal had a significantly lower risk of CIED infection, with a hazard ratio of 0.32 (95% confidence interval, 0.12-0.83; P = 0.019).

CONCLUSIONS

Capsule debridement during CIED replacement was associated with a significant reduction of CIED infection risk. There is a need for randomized controlled studies to confirm these findings.

The Burden and Risk Factors for Infection of Transvenous Cardiovascular Implantable Electronic Device: a Nationwide Cohort Study

BACKGROUND AND OBJECTIVES

There are limited published data on the incidence and cost associated with cardiac implantable electrical device (CIED) infection for Asian patients. We analyzed the infection burden associated with the implantation of CIEDs in Korea.

METHODS

In the Health Insurance Review & Assessment Service (HIRA) database during the period from January 1, 2014 to December 31, 2016, we identified 16,908 patients with CIED implantation. CIED infection was defined as either: 1) Infection-related diagnosis code by the Korean Standard Classification of Diseases after any CIED procedure; or 2) CIED removal along with systemic infection.

RESULTS

The proportions of first implantation and replacement were 77.6% and 22.4%, respectively. During the follow-up period of 17.1±10.6 months, a total of 462 patients had CIED infection with incidence of 1.95 per 100 person-years with higher infection rate in replacement than first implantation (3.97 vs. 1.4 per 100 person-years, p<0.001). The average cost per person was US$ 16,584 (pacemaker, $13,736; implantable cardioverter defibrillator, $28,402; cardiac resynchronization therapy, $29,674). The risk factors of CIED infection were generator replacement (adjusted hazard ratio [aHR], 3.14; 95% confidence interval [CI], 2.60-3.78), diabetes mellitus (aHR, 1.94; 95% CI, 1.58-2.38), and congestive heart failure (aHR, 1.86; 95% CI, 1.51-2.28).

CONCLUSIONS

The rate of CIED infection in Korea was 1.95 per 100 person-years with average cost of US$ 16,584. The most important risk factor was generator replacement. This result suggests that generator replacement should be performed cautiously to avoid CIED infection.

Seasonal variations in cardiac implantable electronic device infections

Infections of cardiac implantable electronic devices (CIEDs) have increased over the past decade. However, the impact of the climate on CIED infections is unknown. To determine whether there is a seasonal variation in CIED infections. In this single-center observational study, retrospective analysis of prospectively collected data was performed. Timone Hospital in Marseille (south-east France) is a tertiary care institution and the regional reference center for management of CIED infections. All consecutive patients with CIED extractions for infectious reasons were included over a 12-year period. We noted the mean temperature (°C), precipitation (mm) and the incidence of CIED infections over this period. Among 612 patients [mean (standard deviation) age, 72.4 (13.0) years; 74.0% male], 238 had endocarditis alone (38.9%), 249 had pocket infection alone (40.7%), and 125 had both (20.4%). We found bacterial documentation in 428 patients (70.0%), commensal in 245 (40.0%). The incidence of CIED infections was positively associated with high temperature (regression coefficient = 0.075; P = 0.01) and precipitation (regression coefficient = 0.022; P < 0.01). Seasonal variation was specific of pocket infections, whether they were associated with endocarditis or not. Subgroups with infection seasonality were: women, elderly people (> 75 years), late CIED infection and skin commensal bacterial infections. We found a seasonal variation in pocket infections, whether associated with endocarditis or not. Infections were associated with elevated temperatures and precipitation. Therefore, specific prevention strategy should be discussed in high-risk patients.

Effect of intraoperative local application of 3% hydrogen peroxide on pocket infections following cardiac implantable electronic device implantation: An observational study

Aims

Methods

Results

Conclusion

New Insights into Predictors of Cardiac Implantable Electronic Device Infection

Infection is an important complication of cardiac implantable electronic device procedures. To further study the factors associated with infection, we retrospectively reviewed the records of 3,205 consecutive patients who had undergone de novo or revision cardiac electronic device implantation at our institution from March 2011 through March 2015. We recorded all infections and specified whether they were related to the characteristics of the patient, device, or procedure. To identify predictors of infection, we performed multivariate analysis. Device infections were identified in 85 patients (2.7%), at a mean follow-up time of 27 ± 11 months. The main predictors of device infection were use of an implantable cardioverter-defibrillator or a cardiac resynchronization therapy defibrillator device (odds ratio [OR]=16; 95% CI, 4.14-61.85; P=0.0001), stage 3 chronic kidney disease (OR=9.41; 95% CI, 1.77-50.04; P=0.009), a revision procedure (OR=8.8; 95% CI, 3.37-23.2; P=0.0001), or postoperative hematoma (OR=6.9; 95% CI, 1.58-30.2; P=0.01). We also identified 2 novel predictors of infection: a low body mass index of <20 kg/m² (OR=1.03; 95% CI, 1.01-1.06; P=0.005), and use of povidone-iodine rather than chlorhexidine-alcohol for topical antisepsis (OR=4.4; 95% CI, 2.01-9.4; P=0.03). We conclude that comorbidities, device characteristics, procedure types, and postoperative noninfective complications all increase the risk of device infection after a cardiac implantable electronic device procedure.

The Composition and Structure of Biofilms Developed by Propionibacterium acnes Isolated from Cardiac Pacemaker Devices

The present study aimed to understand the biofilm formation mechanism of Propionibacterium acnes by analyzing the components and structure of the biofilms. P. acnes strains were isolated from the surface of explanted cardiac pacemaker devices that exhibited no clinical signs of infection. Culture tests using a simple stamp culture method (pressing pacemakers against the surface of agar plates) revealed frequent P. acnes colonization on the surface of cardiac pacemaker devices. P. acnes was isolated from 7/31 devices, and the isolates were categorized by multilocus sequence typing into five different sequence types (STs): ST4 (JK18.2), ST53 (JK17.1), ST69 (JK12.2 and JK13.1), ST124 (JK5.3), ST125 (JK6.2), and unknown ST (JK19.3). An in vitro biofilm formation assay using microtiter plates demonstrated that 5/7 isolates formed biofilms. Inhibitory effects of DNase I and proteinase K on biofilm formation varied among isolates. In contrast, dispersin B showed no inhibitory activity against all isolates. Three-dimensional live/dead imaging of P. acnes biofilms with different biochemical properties using confocal laser microscopy demonstrated different distributions and proportions of living and dead cells. Additionally, it was suggested that extracellular DNA (eDNA) plays a role in the formation of biofilms containing living cells. Ultrastructural analysis of P. acnes biofilms using a transmission electron microscope and atmospheric scanning electron microscope revealed leakage of cytoplasmic components along with cell lysis and fibrous structures of eDNA connecting cells. In conclusion, the biochemical properties and structures of the biofilms differed among P. acnes isolates. These findings may provide clues for establishing countermeasures against biofilm-associated infection by P. acnes.

Prevention, Diagnosis, and Treatment of Cardiac Implantable Electronic Device Infections

Cardiac implantable electronic device (CIED) infections are complex medical problems that are increasingly encountered. They are associated with significant morbidity and mortality with tremendous economic cost. The current review will emphasize the prevention, diagnosis, and treatment of this clinical entity using the relatively limited evidence that is currently available. Because there is a paucity of high quality evidence regarding prevention, diagnosis, and treatment of CIED infections, this review will attempt to summarize the best evidence as well as to suggest, when possible, paradigms for care. The topic of CIED infections is a dynamic one as the scope of CIED continues to widen. Furthermore, there are promising advancements in CIED technology which may help reduce its occurrence the future. Unfortunately, significant gaps in knowledge remain, and definitive recommendations regarding CIED infections and future studies should be directed at improving our ability to prevent infections.

Septic Pulmonary Embolism Caused by Infected Pacemaker Leads After Replacement of a Cardiac Resynchronization Therapy Device

BACKGROUND Cardiac resynchronization therapy (CRT) has been demonstrated to reduce morbidity and mortality in patients with advanced, drug-refractory heart failure. Procedure-related mortality is less than 1% in larger studies. Approximately10% of CRT patients have to undergo surgical revision because of infections, dislocations, or unacceptable electrical behavior manifested as high threshold, unstable sensing, or unwanted phrenic nerve stimulation. CASE REPORT A 70-year-old man with symptomatic congestive heart failure underwent implantation of a biventricular pacemaker on the left anterior chest wall in 2003 and pulse generator exchange in August 2009. The patient responded well to CRT. At follow-up, the pacing system functioned normally. In September 2009, in the context of a predialysis program, an abdominal computed tomography (CT) scan was performed in another hospital for assessment and evaluation of chronic kidney disease. This procedure was complicated with peripheral thrombophlebitis that was managed appropriately with complete recovery. Eight months later (May 2010), the patient was admitted to our hospital with fever, anemia, and elevated infection parameters. During admission, blood cultures grew Staphylococcus epidermidis. The chest X-ray, lung perfusion scintigraphy, and CT scan depicted pulmonary embolism and infarction. The right ventricular lead threshold was found to be increased to 7 volts with unsuccessful capture. Echocardiography demonstrated vegetations on leads. The entire pacing system was explanted, but the patient expired few days later following percutaneous removal due to multiorgan failure. CONCLUSIONS In heart failure, replacement of the CRT device may be complicated by bacterial endocarditis. As noted from this case report, sudden elevation of the pacing lead threshold should prompt thorough and immediate investigation to unravel its causes, not only the electrical characteristics but also the anatomical features.

Going beyond the Control of Quorum-Sensing to Combat Biofilm Infections

Most bacteria attach to surfaces where they form a biofilm, cells embedded in a complex matrix of polymers. Cells in biofilms are much better protected against noxious agents than free-living cells. As a consequence it is very difficult to control pathogens with antibiotics in biofilm infections and novel targets are urgently needed. One approach aims at the communication between cells to form and to maintain a biofilm, a process called quorum-sensing. Water soluble small-sized molecules mediate this process and a number of antagonists of these compounds have been found. In this review natural compounds and synthetic drugs which do not interfere with the classical quorum-sensing compounds are discussed. For some of these compounds the targets are still not known, but others interfere with the formation of exopolysaccharides, virulence factors, or cell wall synthesis or they start an internal program of biofilm dispersal. Some of their targets are more conserved among pathogens than the receptors for quorum sensing autoinducers mediating quorum-sensing, enabling a broader application of the drug. The broad spectrum of mechanisms, the diversity of bioactive compounds, their activity against several targets, and the conservation of some targets among bacterial pathogens are promising aspects for several clinical applications of this type of biofilm-controlling compound in the future.

Microbial diagnosis of infection and colonization of cardiac implantable electronic devices by use of sonication

OBJECTIVES

The clinical utility of sonication as an adjunctive diagnostic tool for the microbial diagnosis of cardiac implantable device-associated infections (CIDAIs) was investigated.

METHODS

The implants of 83 subjects were investigated, 15 with a CIDAI and 68 without a clinical infection. Clinical data were analyzed prospectively and sonication fluid cultures (83 patients, 100%) and traditional cultures (31 patients, 37.4%) were performed

RESULTS

Generator pocket infection and device-related endocarditis were found in 13 (86.7%) and four (26.7%) subjects, respectively. The mean numbers of previous technical complications and infections were higher in the infected patients compared to the non-infected patients (8 vs. 1, p<0.001; 2 vs. 0, p<0.031, respectively). The sensitivity and specificity for detecting CIDAI was 73.3% (11/15) and 48.5% (33/68) for sonication fluid culture, and 26.7% (4/15) and 100% (16/16) for traditional culture (p<0.001), respectively. A higher number of organisms were identified by sonication fluid than by tissue culture (58 vs. 4 specimens; p<0.001). The most frequent organisms cultured were Gram-positive cocci (66.1%), mainly coagulase-negative staphylococci (35.5%). Thirty-five (51.5%) non-infected subjects were considered colonized due to the positive identification of organisms exclusively through sonication fluid culture.

CONCLUSIONS

Sonication fluid culture from the removed cardiac implants has the potential to improve the microbiological diagnosis of CIDAIs.

Usefulness of sonication of cardiovascular implantable electronic devices to enhance microbial detection

The cardiovascular implantable electronic device (CIED) infection rate is rising disproportionately to the rate of device implantation. Identification of microorganisms that cause CIED infections is not always achieved using present laboratory techniques. We conducted a prospective study to determine whether device vortexing-sonication followed by culture of the resulting sonicate fluid would enhance microbial detection compared with traditional swab or pocket tissue cultures. Forty-two subjects with noninfected and 35 with infected CIEDs were prospectively enrolled over 12 months. One swab each from the device pocket and device surface, pocket tissue, and the CIED were collected from each patient. Swabs and tissues were cultured using routine methods. The CIED was processed in Ringer's solution using vortexing-sonication and the resultant fluid semiquantitatively cultured. Tissue and swab growth was considered significant when colonies grew on ≥2 quadrants of the culture plate and device was considered significant when ≥20 colonies were isolated from 10 ml of sonicate fluid. In noninfected group, 5% of sonicate fluids yielded significant bacterial growth, compared with 5% of tissue cultures (p = 1.00) and 2% of both pocket and device swab cultures (p = 0.317 each). In infected group, significant bacterial growth was observed in 54% of sonicate fluids, significantly greater than the sensitivities of pocket swab (20%, p = 0.001), device swab (9%, p <0.001), or tissue (9%, p <0.001) culture. In conclusion, vortexing-sonication of CIEDs with semiquantitative culture of the resultant sonicate fluid results in a significant increase in the sensitivity of culture results, compared with swab or tissue cultures.

Identification of bacteriology and risk factor analysis of asymptomatic bacterial colonization in pacemaker replacement patients

Background

Recent researches revealed that asymptomatic bacterial colonization on PMs might be ubiquitous and increase the risk of clinical PM infection. Early diagnosis of patients with asymptomatic bacterial colonization could provide opportunity for targeted preventive measures.

Objective

The present study explores the incidence of bacterial colonization of generator pockets in pacemaker replacement patients without signs of infection, and to analyze risk factors for asymptomatic bacterial colonization.

Methods

From June 2011 to December 2013, 118 patients underwent pacemaker replacement or upgrade. Identification of bacteria was carried out by bacterial culture and 16S rRNA sequencing. Clinical risk characteristics were analyzed.

Results

The total bacterial positive rate was 37.3% (44 cases), and the coagulase-negative Staphylococcus aureus detection rate was the highest. Twenty two (18.6%) patients had positive bacterial culture results, of which 50% had coagulase-negative staphylococcus. The bacterial DNA detection rate was 36.4 % (43 cases). Positive bacterial DNA results from pocket tissues and the surface of the devices were 22.0% and 29.7%, respectively. During follow-up (median, 27.0 months), three patients (6.8%, 3/44) became symptomatic with the same genus of microorganism, S. aureus (n=2) and S. epidermidis (n=1). Multivariable logistic regression analysis showed that history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency were independent risk factors for asymptomatic bacterial colonization.

Conclusion

There was a high incidence of asymptomatic bacterial colonization in pacemaker patients with independent risk factors. Bacterial culture combined genetic testing could improve the detection rate.

Management of Cardiac Implantable Electronic Device Infection

Despite improved preventive measures, infection associated with the use of cardiac implantable electronic devices (CIEDs) to treat often life-threatening conditions is rising at an average annual rate of almost 5 %. This rise is being driven by the increasing complexity of CIED technology and by the advancing age and co-morbidities of the patients. Although CIED infection is usually suspected based on local signs at the generator pocket site, diagnosis can be challenging in patients presenting no local manifestations or symptoms. Diagnostic methods include microbiological testing and echocardiography, and may be completed by positron emission tomography (PET)/computed tomography (CT) scan in selected cases. CIED infection requires a multidisciplinary approach in view of hardware extraction, targeted antibiotic therapy and reimplantation on an as-needed basis. Antibiotic prophylaxis targeting staphylococcal flora is recommended but the relation of these infections to medical care exposes patients to multi-resistant bacteria. New preventive measures utilising an antibacterial sleeve look promising. Treatment can be started on an empirical basis using an antistaphylococcal agent but must be continued using targeted antibiotic therapy. Crucial questions remain as to the best prevention strategy, optimal duration and timing of antibiotic therapy, and the most effective reimplantation technique.

Genetic identification and risk factor analysis of asymptomatic bacterial colonization on cardiovascular implantable electronic devices

Asymptomatic bacterial colonization of cardiovascular implantable electronic devices (CIEDs) is widespread and increases the risk of clinical CIED infection. The aim of the study was to evaluate the incidence of bacterial colonization of generator pockets in patients without signs of infection and to analyze the relationship with clinical infection and risk factors. From June 2011 to December 2012, 78 patients underwent CIED replacement or upgrade. Exclusion criteria included a clinical diagnosis of CIED infection, bacteremia, or infective endocarditis. All patients were examined for evidence of bacterial 16S rDNA on the device and in the surrounding tissues. Infection cases were recorded during follow-up. The bacterial-positive rate was 38.5% (30 cases); the coagulase-negative Staphylococcus detection rate was the highest (9 cases, 11.5%). Positive bacterial DNA results were obtained from pocket tissue in 23.1% of patients (18 cases), and bacterial DNA was detected on the device in 29.5% of patients (23 cases). During follow-up (median 24.6 months), two patients (6.7%, 2/30) became symptomatic with the same species of microorganism, S. aureus and S. epidermidis. Multivariable logistic regression analysis found that the history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency, and renal insufficiency were independent risk factors for asymptomatic bacterial colonization.

Guidelines for the diagnosis, prevention and management of implantable cardiac electronic device infection. Report of a joint Working Party project on behalf of the British Society for Antimicrobial Chemotherapy (BSAC, host organization), British Heart Rhythm Society (BHRS), British Cardiovascular Society (BCS), British Heart Valve Society (BHVS) and British Society for Echocardiography (BSE)

Infections related to implantable cardiac electronic devices (ICEDs), including pacemakers, implantable cardiac defibrillators and cardiac resynchronization therapy devices, are increasing in incidence in the USA and are likely to increase in the UK, because more devices are being implanted. These devices have both intravascular and extravascular components and infection can involve the generator, device leads and native cardiac structures or various combinations. ICED infections can be life-threatening, particularly when associated with endocardial infection, and all-cause mortality of up to 35% has been reported. Like infective endocarditis, ICED infections can be difficult to diagnose and manage. This guideline aims to (i) improve the quality of care provided to patients with ICEDs, (ii) provide an educational resource for all relevant healthcare professionals, (iii) encourage a multidisciplinary approach to ICED infection management, (iv) promote a standardized approach to the diagnosis, management, surveillance and prevention of ICED infection through pragmatic evidence-rated recommendations, and (v) advise on future research projects/audit. The guideline is intended to assist in the clinical care of patients with suspected or confirmed ICED infection in the UK, to inform local infection prevention and treatment policies and guidelines and to be used in the development of educational and training material by the relevant professional societies. The questions covered by the guideline are presented at the beginning of each section.

Prevention of pacemaker infections with perioperative antimicrobial treatment: an in vitro study

AIMS

The antimicrobial treatment of pacemaker casings with antiseptics (povidone-iodine or octenidine dihydrochloride) or antibiotics (vancomycin, daptomycin, cefuroxime, Tazobac, or nebacetin) was analysed in vitro for its biocompatibility and efficacy in preventing the bacterial adhesion of Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli to cardiac-implantable electrophysiological devices (CIEDs).

METHODS AND RESULTS

Titan platelets (0.4 cm&sup2;) cut from pacemaker casings were impregnated with seven different antimicrobial solutions: two antiseptics and five antibiotics. Subsequently, they were challenged with bacterial contamination by four test strains over a 24 h incubation period. Bacterial adherence was quantified using the colony-forming-unit method after cell recovery with sonication and examined with confocal laser scanning electron microscopy. Simultaneously, the biocompatibility of the antimicrobial impregnation was assessed using pre-treated titan platelets in a culture of human fibroblasts, skeletal myoblasts, and microvascular endothelial cells. After a 48 h incubation, cell vitality was measured using the 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H/tetrazolium monosodium (WST-8) assay. The immersion of pacemaker casings in antiseptic or antibiotic solutions applies an antimicrobial coating that can significantly reduce bacterial adhesion. The studied impregnations differed in their antimicrobial efficacy and toxicity.

CONCLUSION

Compared with the two antiseptics and the other tested antibiotics, nebacetin showed the best ratio of efficacy to toxicity. Nebacetin showed good in vitro antibacterial activity against both Gram-positive and Gram-negative pathogens without impairing human cell vitality. It is a safe and effective candidate for CIED impregnation.

Broad-range PCR: past, present, or future of bacteriology?

PCR targeting the gene encoding 16S ribosomal RNA (commonly named broad-range PCR or 16S PCR) has been used for 20 years as a polyvalent tool to study prokaryotes. Broad-range PCR was first used as a taxonomic tool, then in clinical microbiology. We will describe the use of broad-range PCR in clinical microbiology. The first application was identification of bacterial strains obtained by culture but whose phenotypic or proteomic identification remained difficult or impossible. This changed bacterial taxonomy and allowed discovering many new species. The second application of broad-range PCR in clinical microbiology is the detection of bacterial DNA from clinical samples; we will review the clinical settings in which the technique proved useful (such as endocarditis) and those in which it did not (such as characterization of bacteria in ascites, in cirrhotic patients). This technique allowed identifying the etiological agents for several diseases, such as Whipple disease. This review is a synthesis of data concerning the applications, assets, and drawbacks of broad-range PCR in clinical microbiology.

The oral cavity is not a primary source for implantable pacemaker or cardioverter defibrillator infections

Background

To test the hypothesis that the oral cavity is a potential source for implantable pacemaker and cardioverter defibrillators infections, the bacterial diversity on explanted rhythm heart management devices was investigated and compared to the oral microbiome.

Methods

A metagenomic approach was used to analyze the bacterial diversity on the surfaces of non-infected and infected pacemakers. The DNA from surfaces swaps of 24 non-infected and 23 infected pacemaker were isolated and subjected to bacterial-specific DNA amplification, single strand conformation polymorphism- (SSCP) and sequencing analysis. Species-specific primer sets were used to analyze for any correlation between bacterial diversity on pacemakers and in the oral cavity.

Results

DNA of bacterial origin was detected in 21 cases on infected pacemakers and assigned to the bacterial phylotypes Staphylococcus epidermidis, Propionibacterium acnes, Staphylococcus aureus, Staphylococcus schleiferi and Stapyhlococcus. In 17 cases bacterial DNA was found on pacemakers with no clinical signs of infections. On the basis of the obtained sequence data, the phylotypes Propionibacterium acnes, Staphylococcus and an uncultured bacterium were identified. Propionibacterium acnes and Staphylococcus epidermidis were the only bacteria detected in pacemeaker (n = 25) and oral samples (n = 11).

Conclusions

The frequency of the coincidental detection of bacteria on infected devices and in the oral cavity is low and the detected bacteria are highly abundant colonizers of non-oral human niches.

The transmission of oral bacteria to the lead or device of implantable pacemaker or cardioverter defibrillators is unlikely relevant for the pathogenesis of pacemaker or cardioverter defibrillators infections.

Sonication of explanted cardiac implants improves microbial detection in cardiac device infections

The sonication technique has been shown to be a promising tool for microbiological diagnosis of device-related infections. We evaluated the usefulness of the sonication method for pathogen detection in 80 explanted cardiac components collected from 40 patients, and the results were compared with those of conventional cultures. Forty subjects undergoing cardiac device removal were studied: 20 had cardiac device infection, and 20 subjects underwent elective generator replacement or revision in the absence of infection. Sonication of explanted devices was more sensitive than traditional culture for microbial detection (67% and 50%, respectively; P = 0.0005). The bacterial count detected in sonication fluid culture was significantly higher than that detected in traditional culture in both infected (P = 0.019) and uninfected (P = 0.029) devices. In the infected patients, sonication fluid culture yielded a significantly higher rate of pathogen detection in explanted electrodes than traditional culture (65% versus 45%; P = 0.02), while no differences were found in the generators. Ten strains were detected only through sonication fluid culture: 6 Staphylococcus epidermidis strains, 1 Staphylococcus hominis strain, 2 Corynebacterium striatum strains, and 1 Brevundimonas sp. Neither the type nor the duration of antimicrobial therapy before device removal had an effect on the diagnostic performance of sonication fluid culture (P = 0.75 and P = 0.56, respectively). In the patients without infection, sonication fluid culture was positive in 8 cases (40%), whereas conventional culture was positive in only 4 (20%). In summary, the sonication technique improves the microbiological diagnosis of explanted cardiac devices.

Novel approaches to the diagnosis, prevention, and treatment of medical device-associated infections

The pathogenesis of device-associated infections is related to biofilm bacteria that exhibit distinct characteristics with respect to growth rate, structural features, and protection from host immune mechanisms and antimicrobial agents when compared with planktonic counterparts. Biofilm-associated infections are prevented, diagnosed, and treated differently from infections not associated with biofilms. This article reviews innovative concepts for the prevention of biofilm formation, and novel treatment approaches. Specific approaches for the diagnosis and prevention of catheter-associated urinary tract and bloodstream infections, as well as infections associated with orthopedic implants and cardiovascular implantable electronic devices, are also discussed.

Antimicrobial prophylaxis in noncardiac prosthetic device recipients

BACKGROUND

Secondary antimicrobial prophylaxis involves the use of ≥ 1 antimicrobial agent just prior to the time when a diagnostic/therapeutic procedure, which may induce infection, is to be performed. In the context of this article, antimicrobial agent(s) are administered to patients with ≥ 1 implanted prosthetic device in order to prevent metastatic seeding of the device(s) during bacteremia induced by a diagnostic/therapeutic procedure. Antimicrobial agents used in this context are only administered periprocedurally. Secondary antimicrobial prophylaxis of endocarditis in recipients of cardiac prosthetic materials (including valves, shunts, conduits, and patches) has been reasonably well established. However, secondary antimicrobial prophylaxis in recipients of other types of prosthetic devices has been the subject of much controversy, with a wide variety of recommendations being made.

OBJECTIVES

The purpose of this article was to conduct a narrative review of the published literature on the topic of secondary antimicrobial prophylaxis in recipients of noncardiac prosthetic devices and make evidence-based recommendations for each type of device, where possible.

METHODS

Medline/PubMed and EMBASE databases were searched for English-language articles published from 1950 to the present (January 2012). Search terms included "prophylaxis," "antibiotics," "antimicrobials," "prosthetic devices," "prosthesis-related infections," "bacteremia," the names of the individual types of prosthetic devices, and the names of the individual procedures potentially inducing bacteremia. Articles dealing with any aspect relevant to this topic were eligible for review. The bibliographies of retrieved articles were also carefully scanned to identify any articles not previously identified.

RESULTS

Based on review of the available literature, secondary antimicrobial prophylaxis is justified in only a few specific circumstances. For recipients of prosthetic vascular grafts/stents, hemodialysis arteriovenous shunts, and ventriculoatrial/ventriculovenous shunts, prophylaxis is warranted during the initial 6 months, initial 6 weeks, and at all times after implantation/revision, respectively, when dental procedures capable of inducing high-level bacteremia are planned. Prosthetic joint recipients should receive prophylaxis in the following 3 circumstances: 1) patient is to undergo dental procedure(s) capable of inducing high-level bacteremia plus either the patient is still within 2 years of device implantation/revision or the patient has ≥ 1 risk factor for hematogenous prosthetic joint infection; 2) patient is to undergo genitourinary tract procedure(s) capable of inducing high-level bacteremia plus the patient has ≥ 1 risk factor for high-risk bacteriuria; and 3) patient is to undergo perforating dermatologic surgery on the oral mucosa or at skin sites at increased risk for surgical site infection plus patient has ≥ 1 risk factor for hematogenous prosthetic joint infection. The data are inadequate to justify secondary antimicrobial prophylaxis for recipients of other types of prosthetic devices. On the basis of 9 surveys of prescriber behavior, it is apparent that there exists, over a wide geographic area, a wide disconnect between clinical practice and the secondary antimicrobial prophylaxis guidelines issued by the professional organizations representing these prescribers. Antimicrobial agent overuse was especially problematic among orthopedic and colorectal surgeons, urologists, and family practitioners. Dentists and maxillofacial surgeons followed guidelines more closely.

CONCLUSION

Device-, procedure-, and patient characteristic-dependent factors elicited over many years have narrowed down the secondary antimicrobial prophylaxis recommendations for noncardiac prosthetic devices to a small number. Despite this, physician prescribers frequently do not follow prophylaxis guidelines established by their own professional organizations. Risk-benefit and cost-effectiveness studies have found that no prophylaxis is actually superior to universal prophylaxis, likely due to known antimicrobial toxicities, such as anaphylactic/anaphylactoid reactions and Clostridium difficile-associated disease. Much work remains in establishing and extending the scientific basis for secondary antimicrobial prophylaxis and transforming this knowledge into appropriate action by the clinician.

Sonication of explanted cardiac rhythm management devices for the diagnosis of pocket infections and asymptomatic bacterial colonization

BACKGROUND

Correct diagnosis of the causative organism is critical for the treatment of pacemaker and defibrillator pocket infections. No gold standard for this exists, although swab and tissue cultures are frequently used. The purpose of this study was to determine the value of ultrasonication of explanted generators in the diagnosis of pocket infections and asymptomatic bacterial colonization.

METHODS

Samples were prospectively collected during pacemaker and defibrillator generator extractions for elective replacements, upgrades, or pocket infections. The devices were placed in an ultrasonicator for 5 minutes and the fluid sent for culture, along with swab and tissue cultures.

RESULTS

Eighty-two patients with pacemakers (n = 46) or defibrillators (n = 36) underwent generator explantation, 66 of these for elective reasons and 16 for pocket infection. In patients with pocket infection, 15 (94%) received a definitive bacterial diagnosis using a combination of all three-culture modalities. Cultures were positive in 15 sonicated fluid, 13 tissue, and 11 swab samples, with Staphylococcus aureus and other skin flora commonly seen. In asymptomatic patients, 14 (21%) had positive cultures. Cultures were positive in 11 sonicated fluid, eight tissue, and two swab samples. Skin flora was commonly seen, but three of the sonicated fluid cultures grew gram-negative rods. No patients with asymptomatic colonization developed clinical infection during the follow-up period.

CONCLUSIONS

Ultrasonication is an inexpensive and simple technique that improves the bacteriologic diagnosis of device pocket infections. It also identifies a significant proportion of patients with asymptomatic colonization, although this is not a marker of future pocket infection.

Infection after pacemaker implantation: infection rates and risk factors associated with infection in a population-based cohort study of 46299 consecutive patients

Aims

Infection is a serious complication of pacemaker (PM) systems. Although the rate of infection has been debated, the figures are largely unknown. We therefore studied the incidence of PM infection and its associated risk factors in the Danish population.

Methods and results

Since 1982, all PM implantation and removal procedures performed in Denmark have been prospectively recorded in the Danish Pacemaker Register. All patients (n = 46299) who underwent implantation between 1982 and 2007 were included. The total length of surveillance was 236 888 PM-years. The incidence of infection was calculated according to the total number of PM-years. The incidence of surgical site infection (≤365 days after PM implantation) was compared with later infection in first implant and replacement procedures. Multiple-record and multiple-event-per-subject proportional hazards analyses were used to identify the independent risk factors of PM infection. Surgical site infection occurred in 192 cases after first implantation (incidence rate 4.82/1000 PM-years), and in 133 cases after replacement (12.12/1000 PM-years). Infections occurring more than 365 days after the first implantation occurred in 153 cases (1.02/1000 PM-years), and in 118 cases after replacement (3.26/1000 PM-years). Independent factors associated with an increased risk of PM infection were a greater number of PM operations (including replacements), male sex, younger age, implantation during the earliest part of the study period, and absence of antibiotics (P< 0.001).

Conclusion

The overall risk of infection after PM implantation was low. A greater number of operations augmented the risk of infection. This should be taken into account when considering revisions of PM systems.

Inhibition of Staphylococcus aureus biofilms by a novel antibacterial envelope for use with implantable cardiac devices

Biofilm formation on representative implantable medical devices using a known human pathogen (Staphylococcus aureus) was significantly reduced (p < 0.01) at all time points measured (24,48, and 72 hours) by employing a novel antibacterial envelope (AIGIS Rx). The result was demonstrated using a standard US Centers for Disease Control (CDC) bioreactor model and the results were confirmed by Scanning Electron Microscopy (SEM). The antibacterial envelope used in the study is coated with a proprietary combination broad spectrum antibiotics (rifampin and minocycline) embedded in a resorbable polymeric coating. The antibiotics are designed to elute out of the coating over a multi-day period for controlled, site-specific drug delivery. The infection rate for patients receiving pacemakers and defibrillators is increasing faster than the rate of new implants and the growing resistance of S. aureus strains suggests that conventional, systemic antibiotic prophylaxis may have limited future utility. Moreover, emerging evidence suggests that bacterial biofilms result in infections of implantable medical devices. These findings demonstrate the in vitro efficacy of a new means to address potential biofilm-derived Hospital Acquired Infections (HAIs) related to implantable medical devices composed of titanium inclusive of pacemakers and defibrillators by means of a locally delivered, low dose, combination antibacterial treatment.

Bacterial colonization of stimulation electrode wires in patients undergoing temporary sacral nerve stimulation

OBJECTIVE

In patients undergoing sacral nerve stimulation (SNS), a temporary percutaneous stimulation wire is often used to assess the clinical response to therapy prior to chronic stimulation. The aim of this study was to evaluate the incidence of bacterial colonization of screening wires and risk of clinical infection in patients undergoing prolonged temporary SNS screening.

METHOD

Data were collected prospectively on a consecutive series of patients undergoing temporary SNS for bowel dysfunction. Procedures were performed using a standardized percutaneous technique with a single shot of either co-amoxyclav 1.2 g or cefuroxime 1.5 g given intravenously on induction. Adherent polyurethane dressings were applied to secure the wire. At the end of the screening period the wire and dressings were removed, the skin entry site was cleaned using an alcohol wipe and the wire removed via an aseptic technique. The distal tip of the wire was then cut and sent for culture.

RESULTS

Thirteen wires were removed at a median of 21 (range 16-29) days following insertion. There were no signs of local or systemic infection. Seven of the thirteen wires (54%) were found to have deep bacterial colonization. The commonest organisms isolated were staphylococcus species. There was no correlation between the length of time the lead had been implanted and the incidence of bacterial colonization.

CONCLUSION

Bacterial colonization of the temporary stimulation wire is common but appears to be associated with a low risk of clinical infection. A single peri-operative dose of antibiotics does not appear to prevent colonization.