Infective Endocarditis in the Intravenous Drug Use Population at a Tertiary Hospital in Melbourne, Australia

Features of infective endocarditis in a contemporary cohort of persons who inject drugs: a matched comparison analysis of long-term prognostic factors

The objective of the study was to assess the short- and long-term mortality of infective endocarditis (IE) among people who inject drugs (PWID). Using prospectively collected data on hospitalized patients (years 2000 through 2021) with IE, PWID were identified and included in this study. Survival analysis was performed to analyze short- and long-term mortality and study their risk factors among PWID and a matched group of non-intravenous drug users (N-IDU). In a study of 485 patients admitted for IE, 55 (11%) of them were PWID. These PWID patients were 1:1 age- and sex- matched to an N-IDU group (N = 55 per group). Both groups had similar baseline comorbid conditions, including congestive heart failure, type 2 diabetes, and neoplastic diseases. However, PWID were more likely to have HCV co-infection (62% vs 16%, respectively, p < 0.001) and advanced liver disease/cirrhosis (52% vs 7.9%, respectively, p < 0.001). IE in PWID more often affected the tricuspid valve (42% vs 22%, respectively, p = 0.024) and presented with more embolic events (66% vs 35%, respectively, p < 0.01). S. aureus was the primary cause of IE in PWID (44% vs 21%, respectively, p = 0.01). After adjusting for other variables, PWID (HR = 2.99, 95% CI [1.06, 8.43], p = 0.038) and valve bioprosthetic replacement (HR = 5.37, 95% CI [1.3, 22.1], p = 0.02) were independently associated with increased mortality risk, whereas IE caused by tricuspid valve infection was associated with reduced mortality risk (HR = 0.25, 95% CI [0.06, 0.97], p = 0.046). In this cohort, PWID had increased risk of long-term mortality after hospital discharge for IE, when compared to matched N-IDU with similar baseline characteristics. The reasons behind the significant increase in mortality warrant further investigation.

Epidemiology of acute infections in people who inject drugs in Australia

ISSUES

People who inject drugs are at risk of acute infections, such as skin and soft tissue infections, infective endocarditis, bone and joint infections and bloodstream infections. There has been an increase in these infections in people who inject drugs internationally over the past 10 years. However, the local data regarding acute infections in Australia has not been well described.

APPROACH

We review the epidemiology of acute infections and associated morbidity and mortality amongst people who inject drugs in Australia. We summarise risk factors for these infections, including the concurrent social and psychological determinants of health.

KEY FINDINGS

The proportion of people who report having injected drugs in the prior 12 months in Australia has decreased over the past 18 years. However, there has been an increase in the burden of acute infections in this population. This increase is driven largely by skin and soft tissue infections. People who inject drugs often have multiple conflicting priorities that can delay engagement in care.

IMPLICATIONS

Acute infections in people who inject drugs are associated with significant morbidity and mortality. Acute infections contribute to significant bed days, surgical requirements and health-care costs in Australia. The increase in these infections is likely due to a complex interplay of microbiological, individual, social and environmental factors.

CONCLUSION

Acute infections in people who inject drugs in Australia represent a significant burden to both patients and health-care systems. Flexible health-care models, such as low-threshold wound clinics, would help directly target, and address early interventions, for these infections.

Brain abscesses in infective endocarditis: contemporary profile and neuroradiological findings

BACKGROUND

Brain abscesses (BA) are severe lesions in the course of infective endocarditis (IE). We compare the bacteriological, clinical data, background, associated lesions, and outcome of IE patients with and without BAs, and assess the MRI characteristics of BAs.

METHODS

Retrospective study of 351 consecutive patients with definite IE (2005-2020) and at least one brain MRI. Patients with and without BAs were compared.

RESULTS

Twenty patients (5.7%) had BA (80% men; median age: 44.9 ± 11.5). They were younger (p = 0.035) and had a higher rate of predisposing factors (previous IE 20% vs 2.2%, p = 0.03), intravenous drug use [25% vs 2.2%; p < 0.0001]), underlying conditions (HIV infection, 20% vs 2.2%, p < 0.0001; alcohol abuse, 20% vs 2.2% p < 0.0001]; liver disease p = 0.04; hemodialysis, p = 0.001; type 2 diabetes, p = 0.001), bacterial meningitis (p = 0.0029), rare species involvement (35% vs 7%, p < 0.0006) and extra-cerebral abscesses (p = 0.0001) compared to patients without BA. Valve vegetations were larger in Group 1 (p = 0.046). Clinical presentation could suggest the diagnosis of BA in only 7/20 (35%) patients. MR identified 58 BAs (mean/patient 2.9; range 2-12): often multiple (80%), bilateral (55%) and ≤ 10 mm (72%). The presence of BA did not modify cardiac surgery indication and timing. Favorable outcome was observed in 85% of patients.

CONCLUSION

Rates of predisposing, underlying conditions, rare IE agents, meningitis and metastatic abscesses are significantly higher in BA-IE patients. As BAs can develop in asymptomatic IE patients, the impact of brain MRI on their management needs thoroughly to be further investigated.

The Epidemiology of Infective Endocarditis in New South Wales, Australia: A Retrospective Cross-Sectional Study From 2001 to 2020

OBJECTIVES

This study aimed to investigate the demographic differences amongst patients diagnosed with infective endocarditis (IE), predictors of adverse events, and the association between clinical decision-making and adverse health outcomes amongst patients with IE.

DESIGN

A retrospective cross-sectional study was conducted using the New South Wales (NSW) Admitted Patient Data Collection (APDC) from the Centre for Health Record Linkage (CHeReL).

PARTICIPANTS

All patients (N=18,044) from 2001 to 2020 in New South Wales who received a diagnosis of IE using ICD-10-AM diagnostic code 133.0 were included.

METHODS

Categorical variables were compared using the chi-square test or Fisher's exact test, while the t-test was used for continuous variables. The association between clinical decision-making and adverse health outcomes amongst patients with IE were examined via generalised linear mixed models.

RESULTS

Sex, age, birthplace and referral impacted clinical decision-making, in-hospital death and severity of the disease. Women experienced a higher risk of death and fewer escalations of care. Admission and mortality increased with age, with those aged 60 and above responsible for 60.8% of hospitalisations. Despite octogenarians making up one-fifth of admissions and having the worst mortality rate (15.1%), they experienced only one in 10 intensive care (ICU) admissions. Overseas-born patients had fewer escalations of care and experienced less severe disease if referred by a medical practitioner. One out of 10 admissions that resulted in a hospital death were given non-emergency status, and one in two ICU patients died in hospital.

CONCLUSIONS

Sex, age, place of birth, and clinical decision-making were important predictors of severe disease and death in hospital, lending weight that health care clinical decisions may adversely impact health outcomes for populations of interest.

Acute injection-related infections requiring hospitalisation among people who inject drugs: Clinical features, microbiology and management

INTRODUCTION

People who inject drugs are at risk of hospitalisation with injection-related infections (IRI). We audited the clinical features, microbiology and management of IRI at a tertiary service in Melbourne to describe the burden and identify quality improvement opportunities.

METHODS

We performed retrospective review of IRI admissions from January 2017 to April 2019. We extracted admissions where ICD-10 codes or triage text suggested injecting drug use, and the diagnosis suggested IRI. We reviewed these for eligibility and extracted data using a standardised form. We performed mixed-effects logistic regression to determine predictors of unplanned discharge.

RESULTS

From 574 extracted candidate admissions, 226 were eligible, representing 178 patients. Median age was 41 years (interquartile range 36-47), 66% (117/178) male and 49% (111/226) had unstable housing. Over 50% (96/178) had a psychiatric diagnosis and 35% (62/178) were on opioid agonist therapy (OAT) on admission. Skin and soft tissue infection was the most common IRI (119/205, 58%), followed by bacteraemia (36/205, 18%) and endocarditis (26/205, 13%). Management included addictions review (143/226, 63%), blood-borne virus screening (115/226, 51%), surgery (77/226, 34%) and OAT commencement (68/226, 30%). Aggression events (54/226, 15%) and unplanned discharge (69/226, 30%) complicated some admissions. Opioid use without OAT was associated with almost 3-fold increased odds of unplanned discharge compared to no opioid use (odds ratio 2.90, 95% confidence interval 1.23, 6.85, p = 0.015).

DISCUSSION AND CONCLUSION

Comorbidities associated with IRI may be amenable to opportunistic intervention during hospitalisation. Further research is needed to develop optimal models of care for this vulnerable patient group.

Epidemiologic and clinical characteristics of infective endocarditis: a single-center retrospective study in the Bronx, New York

OBJECTIVE

There is paucity of data on the epidemiological, microbiological, and clinical characteristics of patients admitted with infective endocarditis (IE) in the Bronx, New York.

PATIENT AND METHODS

We conducted a retrospective study at Jacobi Medical Center, a tertiary care hospital in the Bronx. All adult patients who were hospitalized with a primary diagnosis of new-onset IE between January 1st, 2010 and September 30th, 2020 were included. The primary outcome was in-hospital mortality. A logistic regression model was used to identify baseline variables associated with in-hospital mortality.

RESULTS

182 patients were included in this analysis (female sex: 38.5%, median age: 54 years). 46 patients (25.3%) reported intravenous drug use. 153 patients (84.1%) had positive blood cultures. Staphylococcus aureus (S. aureus) was the most common isolated pathogen (45.1% of monomicrobial IE). Nearly half of the cases secondary to S. aureus were methicillin resistant Staphylococcus aureus (MRSA) (34/69). 164 patients (90.1%) were diagnosed with native valve IE. The mitral valve was involved in 32.4% of patients followed by the aortic valve (19.8%). The in-hospital mortality was 18.1%. The mortality was higher in the cohort 2010-2015 compared to the cohort 2016-2020 (22.1% vs 14.6%). Increasing age, MRSA IE, and active malignancy were the only variables found to have significant association with in-hospital death.

CONCLUSION

S. aureus was the most common causative agent and MRSA accounted for about half of the S. aureus IE cases. The incidence of IE in patients with intravenous drug use increased over time, while the median age decreased. The in-hospital death rate was higher in 2010-2015 compared to 2016-2020.

Embolic phenomena to the limbs are an independent predictor of in-hospital mortality from infective endocarditis

BACKGROUND

Infective endocarditis (IE) is a morbid condition with high mortality. We investigated predictors of in-hospital mortality and embolic phenomena in a contemporary Australasian cohort.

METHODS

We identified all patients with IE admitted between January 2017 and 30th April 2020 (40 months). Patient characteristics, risk factors and clinical outcomes were retrospectively collected and analysed.

RESULTS

One hundred and seventy-two consecutive patients (mean age: 56.8 ± 17.9 years, male: 63%, 114/172) were included. Causative organisms were Staphylococcus aureus (44%, 75/172), Enterococcus faecalis (15%, 26/172), Streptococcus mitis (6%, 10/172) and Staphylococcus epidermidis (3%, 6/172). In-hospital mortality was 15% (25/172). Embolic complications were found among 57% (98/172) of patients, the most common being stroke (23%, 40/172), septic pulmonary emboli (17%, 29/172), splenic and/or renal emboli (17%, 26/172) and peripheral limb emboli (15%, 25/172). Sixty (35%, 60/172) patients underwent cardiac surgery. On multivariable analysis, independent predictors of in-hospital mortality were: increased age (odds ratio: 1.064, per year older, P = 0.001), ICU admission independent of cardiac surgery (OR 9.81, P < 0.001), moderate or severe LV impairment (OR 5.19, P = 0.012) and any sign of embolic phenomena to limbs (OR 5.02, P = 0.006). Multivariable predictors of embolic complications were S. aureus bacteraemia (OR 3.22, P = 0.001) and large vegetation >10 mm (OR 3.04, P = 0.002).

CONCLUSION

We demonstrate predictors of in-hospital mortality and embolic phenomena in our cohort. Though age remains a consistent predictor of mortality, surprisingly, signs of embolic phenomena to the limbs was established as an independent predictor of mortality. The mechanism of this is unclear and warrants further evaluation.

Clinical features, diagnosis and treatment outcome of fungal endocarditis: A systematic review of reported cases

The landscape of fungal endocarditis (FE) has constantly been evolving in the last few decades. Despite the advancement in diagnostic methods and the introduction of newer antifungals, mortality remains high in FE. This systematic review aimed to evaluate the epidemiology, clinical features, diagnostic and therapeutic interventions in patients with FE. We also aim to examine the aforementioned factors as a determinant of mortality in FE. A literature search was performed in PubMed, Google Scholar and Scopus, and all patients ≥18 years with proven fungal endocarditis were included. A total of 220 articles (250 patients) were included in the final analysis. Candida was the commonest aetiology (49.6%), followed by Aspergillus (30%) and Scedosporium species (3.2%). The proportion of prosthetic valve endocarditis (PVE) and intravenous drug users was 35.2% and 16%, respectively. The overall mortality rate was 40%. On multivariate analysis, Aspergillus endocarditis (HR 3.7, 95% CI 1.4-9.7; p = .009) and immunocompromised state (HR 2.8, 95% CI 1.24-6.3; p = .013) were independently associated with mortality. Patients treated with surgery along antifungals had better survival (HR 0.20, 95% CI 0.09-0.42; p < .001) compared to those treated with antifungals alone. Recurrence of FE was reported in 10.4% of patients. In conclusion, FE carries significant mortality, particularly in immunodeficient and Aspergillus endocarditis. We advocate the use of surgery combined with antifungals to improve clinical outcomes.

The quest for the optimal surgical management of tricuspid valve endocarditis in the current era: a narrative review

Tricuspid valve endocarditis (TVE) is a growing concern with increasing rates and mortality burden. The currently changing etiology, the antibiotic resistance and the raise in iatrogenic causes as with implantable cardiac devices [cardiac implantable electronic device (CIED)], represent a challenge for the management of these patients. The progressively widespread use of CIEDs is adding to the more commonly known intravenous (IV) drug abuse in the list of causes. Treatment strategies include medical therapy alone or surgery. From the surgical standpoint tricuspid valve repair, replacement or the staged procedure of valvectomy as bridge to replacement are available options. Treatment of endocarditis related to implantable device is another expanding field which requires a coordinated action with microbiologists in consideration of the microorganism antibiotic resistance. This review summarizes the currently available evidences on TVE including surgical indications, timing of interventions and technical considerations. The conflicting results of the available observational evidences and the non-unanimous consensus on many aspects of TVE impede to reach a definitive conclusion regarding the best management strategy and demands for randomized studies in this field.

Widespread septic embolization in injection drug use mitro-aortic infective endocarditis as a remote cause of death

Injection drug use-related infective endocarditis (IDU-IE) assumes peculiar epidemiological, pathogenetic, and prognostic characteristics that allow to consider it a distinct nosological entity, as well as a current problem of considerable social weight. Incidence is reasonably underestimated because diagnosis is often accidental in postmortem examination when drug-related death is suspected. In many cases, postmortem toxicological examinations are negative for acute drug abuse, and findings of infective endocarditis became relevant in the explanation of the mechanism of death. Extracardiac involvement of infective endocarditis is rarely reported as fatal. Fragmentation and embolization of bacterial vegetations can be associated with parenchymal infarcts, systemic spread of the infectious process by formation of an abscess. A case of septic shock as a consequence of the constant bacteremia determined by the continuous proliferation and release of bacteria into the circulation is presented in an injection drug user with left-sided endocarditis and widespread septic embolization. Authors reviewed forensic and medical literature and promote epidemiological value of medical and forensic autopsy. Extracardiac involvement of infective endocarditis may represent a remote and alternative cause of death in injection drug users, and an early diagnosis can be relevant for prognosis. Postmortem examination still represents a valuable opportunity of learning for clinicians and improving diagnostic accuracy with injection drug users. A call for changing of attitudes and practice toward autopsy is finally demanded.

Characteristics and outcomes of patients with right-sided endocarditis undergoing cardiac surgery

Background

There has been an increasing incidence of right-sided infective endocarditis (RSIE) due to the global rise of intravenous drug use (IVDU) and an increasing number of implantable cardiac electronic devices and central venous catheters. Our aim was to investigate differences in the clinical presentation, microbiological findings and prognosis of patients undergoing surgery for RSIE compared to left-sided infective endocarditis (LSIE).

Methods

Relevant clinical data of all 432 consecutive patients undergoing valve surgery for infective endocarditis (IE) at our institution between January 2009 and December 2018 were retrospectively analyzed. Acquired data included patients' demographic and preoperative comorbidities, manifestation of IE according to the recently modified Duke Criteria, perioperative data and relevant clinical outcomes.

Results

A total of 403 patients (93.3%) underwent surgery for LSIE and twenty-nine patients (6.7%) for RSIE. Eleven patients with RSIE (37.9%) showed a concomitant left-sided infection. Compared to LSIE, RSIE patients were significantly younger [47.5 (40.4-69.3) vs. 65.1 (53.7-74.6); P=0.008] and presented with less comorbidities such as hypertension (41.4% vs. 65.3%; P=0.010) and coronary artery disease (6.9% vs. 29.0%; P=0.010). Rates of IVDU (34.5% vs. 4.5%; P<0.001), human immunodeficiency virus (HIV) (10.3% vs. 1.7%; P=0.023) and hepatitis C virus (HCV) infection (24.1% vs. 5.2%; P=0.001) were greater in RSIE. The proportion of Staphylococcus aureus IE was significantly higher in RSIE compared to LSIE (37.9% vs. 21.1%; P=0.035). 30-day mortality was 6.9% after surgery for RSIE compared to 14.6% after operation for LSIE (P=0.372).

Conclusions

Patients undergoing surgery for RSIE compared to LSIE presented with a higher rate of pulmonary septic emboli, more Staphylococcus aureus infections and larger vegetations. Larger multicenter prospective trials are needed to provide more reliable data on the clinical profile of these patients, in order to determine optimal surgical management.