Infective Endocarditis: A Contemporary Study of Microbiology, Echocardiography and Associated Clinical Outcomes at a Major Tertiary Referral Centre

Abstract

The epidemiology of infective endocarditis (IE) continues to evolve, with antimicrobial resistance and clinical outcomes largely dependent on the environment of acquisition. This study aimed to provide a contemporary review of the microbiology and antimicrobial management of IE and report echocardiographic findings and predictors of adverse outcomes in community-acquired and health care-associated IE. Consecutive presentations of IE to a major Australian tertiary referral centre between January 2011 and April 2016 were examined. Culprit organisms and resistance patterns were recorded, as was transthoracic and transoesophageal echocardiography. Real-world antimicrobial prescription and use of an outpatient parenteral antimicrobial therapy (OPAT) service were also assessed, and clinical outcomes analysed. Of 204 consecutive cases, 30% were associated with health care, a group with a higher burden of comorbidities and more prone to complications. Health care-associated cases had lower rates of surgical intervention but higher mortality. A history of intravenous drug use (IVDU) conferred risk for recurrent IE whereas multivalvular involvement predicted heart failure hospitalisation. Staphylococcus aureus was isolated in 45%. Whilst methicillin resistance remains low, the prevalence of S. aureus IE is increasing. Single antimicrobial agents were commonly used (83%) and therapy via OPAT was safe and significantly reduced length of hospital stay. Not undergoing transoesophageal echocardiography (TOE) or definitive surgical management conferred poorer prognosis. The epidemiology of IE is evolving and there is need for updated epidemiological data and associated clinical outcomes. Environment of acquisition remains important in the face of increasing health care provision and the changing predominance of culprit microorganisms.