Pseudomonas aeruginosa ventricular assist device infections: findings from ineffective phage therapies in five cases

Left ventricular assist devices (LVAD) are increasingly used for management of heart failure; infection remains a frequent complication. Phage therapy has been successful in a variety of antibiotic refractory infections and is of interest in treating LVAD infections. We performed a retrospective review of four patients that underwent five separate courses of intravenous (IV) phage therapy with concomitant antibiotic for treatment of endovascular Pseudomonas aeruginosa LVAD infection. We assessed phage susceptibility, bacterial strain sequencing, serum neutralization, biofilm activity, and shelf-life of phage preparations. Five treatments of one to four wild-type virulent phage(s) were administered for 14-51 days after informed consent and regulatory approval. There was no successful outcome. Breakthrough bacteremia occurred in four of five treatments. Two patients died from the underlying infection. We noted a variable decline in phage susceptibility following three of five treatments, four of four tested developed serum neutralization, and prophage presence was confirmed in isolates of two tested patients. Two phage preparations showed an initial titer drop. Phage biofilm activity was confirmed in two. Phage susceptibility alone was not predictive of clinical efficacy in P. aeruginosa endovascular LVAD infection. IV phage was associated with serum neutralization in most cases though lack of clinical effect may be multifactorial including presence of multiple bacterial isolates with varying phage susceptibility, presence of prophages, decline in phage titers, and possible lack of biofilm activity. Breakthrough bacteremia occurred frequently (while the organism remained susceptible to administered phage) and is an important safety consideration.

Single-Center Experience of Control of Ventilator-Circuit-Transmitted Burkholderia cepacia Outbreak in an Intensive Care Unit

Burkholderia cepacia is an emerging nosocomial pathogen frequently associated with outbreaks, but the exact transmission route of this pathogen can at times be elusive in spite of extensive environmental investigative cultures. Active surveillance for sputum cultures was performed for all patients from September 2008 to September 2009 in an intensive care unit (ICU) with B. cepacia outbreak. With evidence of persistent positive conversion of sputum cultures (colonization) and infections among patients, discontinuing re-usable ventilator circuits was introduced. A total of 689 patients were admitted to this unit for a mean duration of 8.7 ± 7.5 days. There were 489 patients (71.0%) with a stay for one to ten days; 161 (23.4%) patients for 11 to 20 days; and 39 (5.7%) with over 20 days. In the first group, 13.5% of patients had cultures converting from negative to positive, in contrast to 66.7% in the last group (p < 0.01). With intervention of using disposable ventilator circuits since June 2009, the incidence of isolated B. cepacia decreased gradually. The estimated 30-day isolation-free probabilities of the groups before, during, one month (August 2009) after, and two months (September 2009) after this intervention were 38.5%, 47.3%, 66.5%, and 96.0%, respectively (p < 0.01). Furthermore, the effect of discontinuing reusable ventilator circuit persisted in the following 6 years; both total isolates of B. cepacia and the infection caused by it were much lower compared to the outbreak period. In summary, this six-year outbreak in a medical ICU persisted until reusable ventilator circuits were discontinued in 2009. The effect of disposable circuits on the decreased incidence of B. cepacia infection maintained in the following years.

Added value of semi-quantitative analysis of [18F]FDG PET/CT for the diagnosis of device-related infections in patients with a left ventricular assist device

AIMS

Left ventricular assist devices (LVADs) improve quality of life and survival in patients with advanced heart failure, but device-related infections (DRIs) remain cumbersome. We evaluated the diagnostic capability of [18F]FDG PET/CT, factors affecting its accuracy, and the additive value of semi-quantitative analysis for the diagnosis of DRI.

METHODS AND RESULTS

LVAD recipients undergoing [18F]FDG PET/CT between 2012 and 2020 for suspected DRI were retrospectively included. [18F]FDG PET/CT was performed and evaluated in accordance with EANM guidelines. The final diagnosis of DRI, based on multidisciplinary consensus and findings during surgery, whenever performed, was used as the reference for diagnosis. 41 patients were evaluated for 59 episodes of suspected DRI. The clinical evaluation established driveline infection in 32 (55%) episodes, central device infection in 6 (11%), and combined infection in 2 (4%). Visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity for driveline infections of 0.79 and 0.71, respectively, whereas semi-quantitative analysis achieved a sensitivity and specificity of 0.94 and 0.83, respectively. For central device component infection, visual analysis of [18F]FDG PET/CT achieved a sensitivity and specificity of 0.75 and 0.60, respectively. Semi-quantitative analysis using SUVratio achieved a sensitivity and specificity of 1.0 and 0.8, respectively. The increase of specificity for central component infection was statistically significant (P = 0.05).

CONCLUSIONS

[18F]FDG PET/CT reliably predicts the presence of DRI in LVAD recipients. Semi-quantitative analysis may increase the specificity of [18F]FDG PET/CT for the analysis of central device component infection and should be considered in equivocal cases after visual analysis.

Outcomes of chlorhexidine lavage without capsulectomy versus complete capsulectomy after lead extraction for the treatment of cardiac implantable electronic device infection

INTRODUCTION

Capsulectomy is recommended in patients with cardiac implantable electronic device (CIED) infection after transvenous lead extraction (TLE) but is time-consuming and requires extensive tissue debridement. In this study, we describe the outcomes of chlorhexidine gluconate (CHG) lavage in lieu of capsulectomy for the treatment of CIED infections.

METHODS

This retrospective study included patients who underwent TLE for CIED-related infections in two institutions in Colombia. In the capsulectomy group, complete capsulectomy was performed after hardware removal. In the CHG group, exhaustive lavage of the generator pocket with 20 cc of CHG at 2% followed by irrigation with approximately 500 cc of normal saline (0.9% sodium chloride) was performed. The primary outcomes included reinfection and hematoma formation in the generator pocket. Secondary outcomes included the occurrence of any adverse reaction to chlorhexidine, the need for reintervention, infection-related mortality, and total procedural time.

RESULTS

A total of 102 patients (mean age 67.2 ± 13 years, 32.4% female) underwent CIED extraction with either total capsulectomy (n = 54) or CHG (n = 48) lavage. Hematoma formation was significantly higher in the capsulectomy group versus the CHG group (13% vs. 0%, p = .014), with no significant differences in the reinfection rate. Capsulectomy was associated with longer procedural time (133.7 ± 78.5 vs. 89.9 ± 51.8 min, p = .002). No adverse reactions to CHG were found. Four patients (4.3%) died from worsening sepsis: three in the capsulectomy group and one in the CHG group (p = .346).

CONCLUSIONS

In patients with CIED infections, the use of CHG without capsulectomy resulted in a lower risk of hematoma formation and shorter procedural times without an increased risk of reinfection or adverse events associated with CHG use.

Deep Brain Stimulator Device Infection: The Mayo Clinic Rochester Experience

Background

Deep brain stimulator (DBS)-related infection is a recognized complication that may significantly alter the course of DBS therapy. We describe the Mayo Clinic Rochester experience with DBS-related infections.

Methods

This was a retrospective study of all adults (≥18 years old) who underwent DBS-related procedures between 2000 and 2020 at the Mayo Clinic Rochester.

Results

There were 1087 patients who underwent 1896 procedures. Infection occurred in 57/1112 (5%) primary DBS implantations and 16/784 (2%) revision surgeries. The median time to infection (interquartile range) was 2.1 (0.9-6.9) months. The odds of infection were higher with longer operative length (P = .002), higher body mass index (BMI; P = .006), male sex (P = .041), and diabetes mellitus (P = .002). The association between infection and higher BMI (P = .002), male sex (P = .016), and diabetes mellitus (P = .003) remained significant in a subgroup analysis of primary implantations but not revision surgeries. Infection was superficial in 17 (23%) and deep in 56 (77%) cases. Commonly identified pathogens were Staphylococcus aureus (65%), coagulase-negative staphylococci (43%), and Cutibacterium acnes (45%). Three device management approaches were identified: 39 (53%) had complete device explantation, 20 (27%) had surgical intervention with device retention, and 14 (19%) had medical management alone. Treatment failure occurred in 16 (23%) patients. Time-to-event analysis showed fewer treatment failures with complete device explantation (P = .015). Only 1 individual had complications with brain abscess at failure.

Conclusions

Primary DBS implantations had higher rates of infection compared with revision surgeries. Complete device explantation was favored for deep infections. However, device salvage was commonly attempted and is a reasonable approach in select cases given the low rate of complications.

Analysis of healthcare-associated infection in patients with pulmonary arterial hypertension associated with congenital heart disease in PICU: Evidence from a tertiary hospital in western China

OBJECTIVE

The present study intends to analyze the targeted surveillance and risk factors for healthcare-associated infection (HAI) in patients with pulmonary arterial hypertension associated with congenital heart disease (CHD-PAH) in a Pediatric intensive care unit (PICU), and provide basis for formulating relevant prevention and control measures of HAI.

METHODS

Children (≤14 years old) who were admitted to the PICU for ≥2 calendar days from January 2018 to December 2021 were included. Targeted surveillance of HAI was described.

RESULTS

A total of 7,828 patients in PICU were monitored, and the total hospitalization days of the patients were 36,174. 108 cases of HAI occurred, with a per-case infection rate of 1.38% and a per-thousand day infection rate of 2.99. 1,129 patients with CHD-PAH were included, among which the total hospitalization days were 1,483. In this subpopulation, 38 cases of HAI were diagnosed, with a per-case infection rate of 3.37% and a per-thousand day infection rate of 25.62. The main site of HAI was lower respiratory tract (43.51%), followed by blood infection (34.26%) and surgical site infection (9.26%). 36 strains of pathogenic bacteria were detected from patients with HAI. The top three pathogens with the highest detection rate were Klebsiella pneumoniae (6 episodes, 16.67%), Enterococcus faecium (6 episodes, 16.67%) and Acinetobacter baumannii (4 episodes, 11.11%). The incidence of VAP, CAUTI and CLABSI was 2.78, 0.08 and 1.66 per 1,000 catheter days respectively. Analysis revealed that patients with CHD-PAH were younger and prone to receive surgical corrections. CHD-PAH could significantly increase the length of ICU stay, ventilator days, times of central venous catheterization and central venous catheterization days. The choice of different central venous catheter types differed significantly between the two groups.

CONCLUSION

Patients with CHD-PAH are characterized with excessive central venous catheterization operations, prolonged indwelling time, and more types of catheterization, which are considered to be risk factors for HAI, thus increasing the length of hospital stay. The clinical etiology is mainly G-bacteria, which requires reasonable selection of antibiotics and strict aseptic operation. Limiting unnecessary invasive procedures is helpful for reducing the incidence of postoperative HAI in PICU.

Staphylococcal Vaccine Antigens related to biofilm formation

The number and frequency of multidrug-resistant (MDR) strains as a frequent cause of nosocomial infections have increased, especially for Methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, in part due to device-related infections. The transition to antibiotic-resistance in related bacterial genes and the capability for immune escape have increased the sustainability of biofilms produced by these bacteria. The formation and changes in biofilms have been suggested as a target to prevent or treat staphylococcal infections. Thus, this study reviews the development of candidate staphylococcal vaccines by database searching, and evaluates the immunogenicity and efficacy profiles of bacterial components involved in biofilms. The literature suggests that using common staphylococcal vaccine antigens and multivalent vaccines should further enhance vaccine efficacy.

Rifampin-Associated Flu-Like Syndrome in a Patient Undergoing Treatment for a Device-Related Infection

Rifampin (or rifampicin) has found extensive use for the treatment of a variety of infectious illnesses, particularly tuberculosis and device-related infections. We describe the development of a flu-like syndrome in a patient undergoing extended antimicrobial therapy with rifampin for discitis and an associated device-related infection, which promptly resolved with discontinuation of rifampin. While the flu-like syndrome has been documented in prior literature covering the treatment of tuberculosis (where the dose regimen tends to be intermittent) there is less evidence for its occurrence in the treatment of device-related infections (which tend to be dosed daily).

Safety and In-Hospital Outcomes of Transvenous Lead Extraction for Cardiac Implantable Device-Related Infections: Analysis of 13 Years of Inpatient Data in the United States

OBJECTIVES

The aim of this study was to investigate the safety and in-hospital outcomes of transcutaneous lead extraction (TLE) associated with device-related infection (DRI) in the United States from 2003 to 2015.

BACKGROUND

DRI remains the most serious complication and the most common indication for lead extraction in patients with cardiac implantable electronic devices. The rates of DRI and associated lead extraction have been growing in line with the increasing number of cardiac implantable electronic device implantations worldwide.

METHODS

Data for this study were drawn from the National (Nationwide) Inpatient Sample. The International Classification of Diseases-9th Revision-Clinical Modification coding system was used to identify hospitalizations with TLE for DRI and to investigate the rates of major adverse events.

RESULTS

From a total of approximately 100 million unweighted hospitalizations over the 13-year study period, 12,257 unweighted observations were identified. This represents 59,082 (95% confidence interval [CI]: 58,982 to 59,182) patients who underwent TLE for DRI during the study period. A large majority of patients (75%) were older than 60 years. Patients were predominantly male (70%) and Caucasian (76%), and 80% had at least 1 comorbidity. The median length of stay was 8 days (interquartile range 5 to 14 days). At least 1 major adverse event occurred in 10.42% of procedures. The all-cause in-hospital mortality rate was 4.11%. Independent predictors of mortality were weight loss (adjusted odds ratio [aOR]: 4.02; 95% CI: 3.13 to 5.17), congestive heart failure (aOR: 3.28; 95% CI: 2.48 to 4.34), chronic kidney disease (aOR: 2.09; 95% CI: 1.70 to 2.56), pericardial complications (aOR: 2.87; 95% CI: 1.79 to 4.61), and procedure-related pulmonary injury (aOR: 2.06; 95% CI: 1.25 to 3.40).

CONCLUSIONS

These results reflect the high rate of complications and mortality for TLE due to DRI in real-world experience, highlighting the importance of comorbidities, especially congestive heart failure and chronic kidney disease, as significant predictors of mortality in these patients.

Direct Microscopic Observation of Human Neutrophil-Staphylococcus aureus Interaction In Vitro Suggests a Potential Mechanism for Initiation of Biofilm Infection on an Implanted Medical Device

The ability of human neutrophils to clear newly attached Staphylococcus aureus bacteria from a serum-coated glass surface was examined in vitro using time-lapse confocal scanning laser microscopy. Quantitative image analysis was used to measure the temporal change in bacterial biomass, neutrophil motility, and fraction of the surface area policed by neutrophils. In control experiments in which the surface was inoculated with bacteria but no neutrophils were added, prolific bacterial growth was observed. Neutrophils were able to control bacterial growth but only consistently when the neutrophil/bacterium number ratio exceeded approximately 1. When preattached bacteria were given a head start and allowed to grow for 3 h prior to neutrophil addition, neutrophils were unable to maintain control of the nascent biofilm. In these head-start experiments, aggregates of bacterial biofilm with areas of 50 μm² or larger formed, and the growth of such aggregates continued even when multiple neutrophils attacked a cluster. These results suggest a model for the initiation of a biofilm infection in which a delay in neutrophil recruitment to an abiotic surface allows surface-attached bacteria time to grow and form aggregates that become protected from neutrophil clearance. Results from a computational model of the neutrophil-biofilm surface contest supported this conceptual model and highlighted the stochastic nature of the interaction. Additionally, we observed that both neutrophil motility and clearance of bacteria were impaired when oxygen tension was reduced to 0% or 2% O₂.

Pathogenic Mechanisms and Host Interactions in Staphylococcus epidermidis Device-Related Infection

Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin and mucous membranes. By adhering to tissue surface moieties of the host via specific adhesins, S. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. In its role as a commensal organism, S. epidermidis is thought to provide benefits to human host, including out-competing more virulent pathogens. However, largely due to its capacity to form biofilm on implanted foreign bodies, S. epidermidis has emerged as an important opportunistic pathogen in patients receiving medical devices. S. epidermidis causes approximately 20% of all orthopedic device-related infections (ODRIs), increasing up to 50% in late-developing infections. Despite this prevalence, it remains underrepresented in the scientific literature, in particular lagging behind the study of the S. aureus. This review aims to provide an overview of the interactions of S. epidermidis with the human host, both as a commensal and as a pathogen. The mechanisms retained by S. epidermidis that enable colonization of human skin as well as invasive infection, will be described, with a particular focus upon biofilm formation. The host immune responses to these infections are also described, including how S. epidermidis seems to trigger low levels of pro-inflammatory cytokines and high levels of interleukin-10, which may contribute to the sub-acute and persistent nature often associated with these infections. The adaptive immune response to S. epidermidis remains poorly described, and represents an area which may provide significant new discoveries in the coming years.

Current Management of Cardiac Implantable Electronic Device Infections by Infectious Disease Specialists

Management guidelines for cardiac implantable electronic device infections exist, but practice patterns of infectious disease (ID) specialists are not well known. We found that while many ID specialist practices mirror existing guidelines, a combination of complete device removal and prolonged antimicrobial therapy is favored when Staphylococcus aureus is involved.

Disseminated Streptococcus pneumoniae infection involving a ventricular assist device

We describe the first reported case, to our knowledge, of disseminated pneumococcal infection involving a left ventricular assist device (LVAD). The management of this infection was extremely challenging, requiring multiple surgical debridements, LVAD removal, and prolonged courses of antibiotics. The Streptococcus pneumoniae isolate was found to be serotype 19F, which is included in both the pneumococcal polysaccharide and conjugate vaccines. This report highlights the importance of routine screening for up-to-date vaccination in patients who undergo LVAD implantation.