Coagulase-negative staphylococci and endocarditis: reappraisal in the 21st century

Abstract

include hemodialysis, peripheral catheters, and central intravascular catheters, as well as invasive procedures such as cardiac catheterization and prostate surgery. It is not surprising that the affected patient population is the elderly and those with comorbid illnesses. Thus, this study and others call attention to the clinical scenarios that are associated with this disease. This study is the first to show that the majority (63%) of patients with CoNS NVE had a vegetation size of < 1 cm. Vegetations this small are often detected only by transesophageal echocardiography and can be missed by transthoracic echocardiography12. This, in addition to the typically subacute clinical presentation of CoNS bloodstream infections, illustrates how CoNS NVE can be missed early in the course of disease. Thus a high degree of suspicion for CoNS NVE in the appropriate clinical setting is important and could potentially have an impact on patient outcomes. The poor outcomes reported in this study are similar to those reported in other studies of CoNS NVE3,8,9. Over one-half of patients suffered from congestive heart failure and approximately 1 in 4 patients died in the hospital. Interestingly, in this study by Haro et al, mortality was higher among patients whose symptoms evolved over fewer than 21 days (on univariate analysis). As suggested by the authors, these patients were likely diagnosed in the hospital setting or under close observation in outpatient clinical settings. Possible explanations for the higher mortality are a sicker patient population or perhaps a more virulent staphylococcal strain acquired in the hospital setting. Although it is impossible to determine based on the current data, the poor outcomes with CoNS NVE are likely due to a combination of host susceptibility and staphylococcal pathogenicity factors. The epidemiology of NVE has changed dramatically over the past few decades. Once predominated by viridans streptococci in the community setting, this disease is increasingly becoming a nosocomial infection due to S. aureus, with CoNS increasing in prevalence7,9. While simple catheter-related CoNS bloodstream infections are common and usually benign, CoNS NVE can be associated with surprisingly poor outcomes. Future efforts should focus on the pathogenesis and prevention of serious CoNS infections.