Pathogen influence on epidemiology, diagnostic evaluation and management of infective endocarditis.

Infective endocarditis (IE) is uncommon and has, in the past, been most often caused by viridans group streptococci (VGS). Due to the indolent nature of these organisms, the phrase 'subacute bacterial endocarditis', so-called 'SBE', was routinely used as it characterised the clinical course of most patients that extended for weeks to months. However, in more recent years, there has been a significant shift in the microbiology of IE with the emergence of staphylococci as the most frequent pathogens, and for IE due to Staphylococcus aureus, the clinical course is acute and can be associated with sepsis. Moreover, increases in IE due to enterococci have occurred and have been characterised by treatment-related complications and worse outcomes. These changes in pathogen distribution have been attributed to a diversification in the target population at risk of IE. While prosthetic valve endocarditis and history of IE remain at highest risk of IE, the rise in prevalence of injection drug use, intracardiac device implantations and other healthcare exposures have heavily contributed to the existing pool of at-risk patients. This review focuses on common IE pathogens and their impact on the clinical profile of IE.