Blood Stream Infection in LVAD Recipients: More than Meets the Eye

Abstract

Background. Left Ventricular Assist Devices (LVAD) have given hope to those with advanced heart failure. Initially, LVADs were thought to be a "bridge to transplant" but now maybe also used as "destination therapy". Infection is one of the most common complications with rates as high as 22-50%. Maimonides Medical Center (MMC) is the only hospital in Brooklyn to have an accredited LVAD Program. Methods. We retrospectively reviewed 51 patients who had undergone LVAD implantation with the Heartmate II at MMC from March 2012 through December 2016. 17 patients with blood stream Infection (BSI) were included in the study. The perioperative antimicrobial regimen in our facility consists of vancomycin, cefepime, rifampin and micafungin. Clinical data including microbiology and occurrence of BSI, and demographics were reviewed. The Maimonides Institutional Review Board approved the study proposal. The International Society for Heart and Lung Transplantation criteria were used to define LVAD infections. Results. Of the 51 patients who had LVAD implantation, 17 patients, with total of 22 episodes, had BSI during the study period. The median age was 72, with 14 males and 3 females. BSI was more common after 6 months of implantation with non-VAD Infections as the most common source. There were 5 episodes of BSI (22%) secondary to a VAD, with the driveline being the most common source (3) followed by pump (2). There were 11 episodes (50%) secondary to non VAD infections, including central venous catheter not associated with VAD. Our study identified Gram-positive organisms as the most common causative pathogen (83%) followed by fungi (13%) and Gram-negative bacteria (4%). Interestingly, of the Gram-positive isolates, 31% were Enterococcus and Streptococcus bovis group without definite source despite extensive workup including colonoscopy. Conclusion. One-third of our patients developed BSI after LVAD implantation and 5 episodes were associated with VAD specific infection. Interestingly, one-third of our patients had bacteremia with enteric pathogens which is not commonly reported in the literature. Our results may help to refine perioperative antimicrobial prophylaxis and empiric treatment regimen for BSI in patients with LVAD. Background. Using the SABG-PCS, we aimed to identify possible temporal variations in the clinical phenotype and bacterial genotype of SAB in a single academic medical center from Jan 1, 1995 to Dec 31, 2015. Methods. SABG-PCS prospectively enrolled all eligible adult hospitalized non-neutropenic patients with monomicrobial SAB at Duke U Med Center (DUMC). Demographic, clinical and outcome data were collected. The initial bloodstream S. aureus isolate from each subject was genotyped using spa typing. Clonal Complex (CC) was inferred using eGenomics software. Proportions of complications and CC were calculated overall and by calendar year. Secular trends in proportions were estimated with linear regression. Results. Among 2,179 unique patients admitted to DUMC with SAB during the study period, 57% were male, and the mean age was 58y. Common comorbidities included end stage renal disease (21.4%), diabetes mellitus (38.1%), and injection drug use (4.5%). Most SAB was community-acquired health-care associated (CA-HCA; 58.8%), followed by hospital-acquired (HA; 34%). Over the course of the study, annual rates increased for CA-HCA SAB (1.3% P < 0.0001) but decreased for HA SAB (-2.1%, P < 0.0001). Although significant annual increases were noted in the overall rate of metastatic complications (0.91%, P = 0.028), including abscesses (0.44%, P = 0.004), vertebral osteomyelitis (0.26%, P = 0.003), and septic emboli (0.63%, P < 0.0001) (Figure 1), rates of endocarditis did not change significantly (0.36%, P = 0.101). Bacterial genotype also shifted during the study period, with annual changes in prevalence of CC30 (-1.3%, P = 0.0002), CC5 (7.5%, P = 0.104) and CC8 (1.4%, P < 0.0001) (Figure 2). Patients with SAB due to CC8 were significantly more likely to develop metastatic complications in general (RR 1.33, 95% CI 1.17-1.51), and metastatic abscess (RR 2.13, 95% CI 1.55-2.93) and septic emboli (RR 1.94, 95% CI 1.31-2.89) in particular. Conclusion. Clinical phenotype and bacterial genotype of SAB in our study cohort changed significantly over the past 21 years. The rise of CC8 in SAB was associated with increased rates of complications in general and abscess in particular. By contrast, rates of endocarditis have remained stable irrespective of genotype distribution.