Among newborn infants, S aureus, coagulase-negative staphylococci, and Candida species are the most common causes of IE.9,13 Less frequently, group B Streptococcus, enteric Gram-negative rod species, and S pneumoniae cause IE in this population. Although catheter-related bacteremias caused by Gram-negative bacilli occur relatively frequently in pediatric patients in intensive care units, IE rarely is caused by these organisms. The rarity of IE caused by Gram-negative bacilli likely is attributable to poor adhesion of Gram-negative bacilli to cardiac valves. Pediatric patients who inject drugs intrave- nously are at risk for IE, especially caused by S aureus. Fungal endocarditis in children usually is caused by Candida species, especially C albicans, although Aspergillus endocarditis also occurs. With the use of CVC in infants and children and infusions with high glucose concentrations and hyperalimentation, Candida infections of the mural or valvu- lar endocardium in infants have occasionally been recognized. Fungal endocarditis is often associated with very large friable vegetations; emboli from these vegetations frequently pro- duce serious complications. Culture-Negative Endocarditis A diagnosis of culture-negative endocarditis (CNE) is made when a patient has clinical or echocardiographic evidence of IE but persistently negative blood cultures. In most centers in the United States, the prevalence of CNE approximates 5% of IE cases in adults and children. However, in more recently published series, CNE was diagnosed in 8% to 36% of patients clinically diagnosed with endocarditis with persistently nega- tive blood cultures.79,84,85 The most common causes of CNE are current or recent antibiotic therapy or infection caused by a fastidious organism such as Abiotrophia and Granulicatella species or an HACEK organism that grows poorly in vitro. Diagnosis of fungal IE is limited by lower sensitivity of blood cultures for yeast and virtually no sensitivity for filamentous fungi. 