Evolving Epidemiology of Infective Endocarditis Requires Updated Data

doctors in laboratory examining test tubes
Trends in infective endocarditis microbiology are of clinical concern and require further study and additional data.

As the epidemiology of infective endocarditis continues to evolve, researchers have identified a need for updated epidemiological data and associated clinical outcomes. This is according to a study recently published in Heart, Lung, and Circulation.

Infective endocarditis diagnosis and treatment remains challenging despite advances in targeted antimicrobial therapy and cardiac imaging. The clinical history of infective endocarditis can be complicated, requiring patients to experience prolonged hospital admissions, and both in-hospital and 5-year mortality are high. As a result, the increase in health care-associated infections in particularly important. Due to recent controversial recommendations against the routine use of prophylactic antibiotic therapy for infective endocarditis in patients undergoing interventional procedures, an updated understanding of the epidemiology of infective endocarditis is pertinent, and the continual re-evaluation of the microbiology of infective endocarditis is needed to document patterns of antimicrobial resistance. This study provided a contemporary review of the microbiology and antimicrobial management of infective endocarditis and reported echocardiographic findings and predictors of adverse outcomes in community-acquired and healthcare-associated infective endocarditis.

In total, 204 consecutive presentations of infective endocarditis to a major Australian tertiary referral center between 2011 and 2016 were examined. Transthoracic and transesophageal echocardiography, culprit organisms, and resistance patterns were recorded. The use and clinical outcomes of real-word antimicrobial prescriptions and outpatient parenteral antimicrobial therapy (OPAT) services were also analyzed.

Within the study cohort (aged 57±18 years; 68% men), 91.2% of cases were diagnosed as definite infective endocarditis. Community-acquired infections were found in 69.6% of patients, while 30.4% were associated with healthcare settings such as hemodialysis. Intravenous drug use accounted for 23% of cases.

To determine the microbiology of infective endocarditis cases, researchers collected a median of 6 blood culture sets (interquartile range [IQR], 4-10), of which 88.7% were positive cases (median 4; IQR, 2-7). Tissue culture was performed in 6 cases; among positive cases, median bacteremia duration was 2 days (IQR, 1-5). The most commonly isolated organism was Staphylococcus aureus, with low rates of methicillin-resistant S aureus (45.1% and 6.4% of cases, respectively). Among patients who survived the index admission, treatment duration was a median of 42 days (IQR, 35-44).

Median duration between transthoracic echocardiography and transesophageal echocardiography was 5 days (IQR, 2-7), with valvular infective endocarditis identified in 187 patients.

In 54.7% of cases, researchers identified septic emboli; these were more common in community-acquired infective endocarditis and infective endocarditis associated with intravenous drug use. Progression rates to both inpatient and elective surgical intervention were similar between cases, regardless of intravenous drug use.

The OPAT program was accessed in 87 cases among patients who survived index admission (n=168). Patients who utilized OPAT services had a significantly shorter median length of hospital say (20 vs 45 days; IQR 15-33 and 32-55, respectively).

Study limitations include those inherent to retrospective analyses, the use of International Classification of Disease codes to identify data, and limitations associated with the use of administrative data.

“The epidemiology of [infective endocarditis] is evolving and there is need for updated epidemiological data and associated clinical outcomes,” the researchers concluded. “[T]here is a paucity of prospective, randomized studies that detail treatments of [infective endocarditis]. Further studies…warrant specific focus.”


Holland DJ, Simos PA, Yoon J, Sivabalan P, Ramnarain J, Runnegar NJ. Infective endocarditis: a contemporary study of microbiology, echocardiography and associated clinical outcomes at a major tertiary referral centre. Heart Lung Circ. 2020;29(6):840-850.