See Table 7 for appropriate dosing of vancomycin. Table 8. Continued Regimen Dosage and Route Duration, wk Strength of Recommendation (Class/LOE) Comments remains difficult, with conflicting data published regard- ing the specific value of echocardiographic determination of vegetation size or specific location as predictors.152,153 Nevertheless, left-sided heart lesions, specifically those involving the mitral valve anterior leaflet, particularly if associated with S aureus, appear to be at highest risk for However, at this time, there are no pediatric evidence-based data to indicate that prophylactic surgery to prevent a primary embolic event is definitively indicated given the immediate and long-term risks of valve replacement in childhood. Other important issues for which early surgery is used include perivalvular extension of infection, fungal endocar- ditis, persistent bacteremia despite appropriate antibiotic therapy, unstable prosthesis, ruptured sinus of Valsalva, or ventricular septal and mycotic aneurysms.156 158 The indica- tions for surgical intervention tabulated in Table 11 should be considered recommendations of experts.17 Although the clinical circumstances seem dire, even difficult aortic root complications can be treated successfully with aortic homografts or Ross procedure autografts.159,160 Depending on the degree of valve or great vessel root damage, valve- sparing operations are often possible.110,152,161 In some Late (>1 y) prosthetic valve placement Coagulase-negative staphylococci S aureus Viridans group streptococci Enterococcus species Fungi Corynebacterium species Dog-cat exposure Bartonella species Pasteurella species Capnocytophaga species Contact with contaminated milk or infected farm animals Brucella species Coxiella burnetii Erysipelothrix species Homelessness, body lice Bartonella species AIDS Salmonella species S pneumoniae S aureus Pneumonia, meningitis S pneumoniae Solid-organ transplant S aureus Aspergillus fumigatus Enterococcus species Candida species Gastrointestinal lesions Streptococcus bovis Enterococcus species Clostridium septicum HACEK indicates Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species. Table 9. Continued Epidemiological Feature Common Microorganism(s) Table 9. 