Few data are available to determine a single best antimicrobial agent, and thus, treatment is individualized according to the judgment of the expert consultant and guided by identification of the organism and antimicrobial suscepti- bility testing. Because these IE cases may be nosocomially acquired, the strains may have unpredictable antimicrobial susceptibilities and may be highly resistant to antimicrobial agents, having many different antibiotic resistance elements, including extended-spectrum -lactamases. Most infectious disease specialists recommend an extended-spectrum peni- cillin (eg, piperacillin/tazobactam) or an extended-spectrum cephalosporin (eg, ceftazidime, ceftriaxone, or cefotaxime) together with an aminoglycoside132 for a minimum of 6 weeks of therapy. There are few data on the use of quinolones for treatment of endocarditis in children, but such therapy has been successful in series of adults with IE. Limited data are available describing treatment of IE caused by Gram-negative pathogens with multidrug resistance (eg, extended-spectrum -lactamase production). Recommendations 1. Therapy for IE caused by the HACEK group should be a 4-week course of ceftriaxone or another third- generation cephalosporin alone, or ampicillin plus gentamicin (Class I; Level of Evidence C). 2. For IE caused by other Gram-negative species, we recommend an extended-spectrum penicillin (eg, piperacillin/tazobactam) or an extended-spectrum cephalosporin (eg, ceftazidime, ceftriaxone, or cefo- taxime) together with an aminoglycoside,132 with choice guided by antibiotic susceptibility of the iso- late and input from an infectious diseases consultant for a minimum of 6 weeks of therapy (Class I; Level of Evidence C). Fungal Endocarditis With the exception of neonates with mural endocarditis and occasionally older children, medical therapy of fun- gal IE is usually unsuccessful. For most patients with fun- gal IE, surgery in conjunction with antifungal agents is required. Early consultation with infectious disease, car- diology, and cardiac surgery services is recommended for these patients. 