It is important to use vancomycin in a proper manner to ensure optimal drug exposure. Despite extensive use of vancomycin in children, studies on its optimal trough concentration (Ctrough) in the pediatric population remained rare. This retrospective study included children < 18 years old with culture-confirmed methicillin-resistant Staphylococcus aureus (MRSA) bacteremia who were hospitalized in our institute from January 2010 to April 2014. Clinical characteristics, initial vancomycin dose, Ctrough and clinical/microbiological outcomes were retrospectively collected from medical records. Forty-six MRSA bacteremia cases occurring to the patients with a mean age of 22.0 ± 46.9 months were included and all of them were healthcare-associated. Severe diseases requiring intensive care unit (ICU) stay, mechanical ventilation and/or resulting in death were observed in 57.8% (26/45); all-cause 30-day fatality was 11.1% (5/45). An initial Ctrough ≥ 15 μg/mL was achieved in only 4 (8.7%) cases with an average vancomycin dosage of 40.6 ± 7.9 mg/kg/day. Persistent bacteremia at 48 hours after initiation of vancomycin was observed more frequently in children with initial Ctrough < 10 μg/mL than in those with Ctrough ≥ 10 μg/mL (P = 0.032). However, there was no statistically significant difference between the two groups in terms of 30-day mortality and recurrent bacteremia (P = 0.899, and P = 0.754, respectively). Although initial Ctrough may be a useful parameter for minimizing early microbiological failure, it does not predict 30-day fatality or recurrence in pediatric MRSA bacteremia. Further prospective data on vancomycin dosing are needed to find the optimal drug exposure and clarify its impact on clinical outcomes in pediatric populations.

Purpose Despite aggressive medical and nutritional management, patients with methylmalonic acidemia (MMA) often suffer from multi-organ damage. Early deceased donor liver transplantation (DDLT) has emerged as an intervention to prevent disease progression. We investigated the efficacy of living donor LT (LDLT) with a potential carrier of MMA and a small volume of graft in patients with MMA as an alternative to DDLT. Methods Of five patients (three male, two female; median age 5.7 years; range, 1.3–13.7 years), four underwent carrier LDLT, while one underwent non-carrier auxiliary LDLT. All patients received pre- and post-LT continuous renal replacement therapy and were provided with minimal restriction diet according to serum MMA level after LT. MMA levels in the serum and urine, the incidence of metabolic crisis, and clinical findings before and after LT were compared. Results The survival rate was 100% during 2.2 years of follow up period after LT. In all five cases, MMA titer in the serum after transplantation decreased with less restrictive diet. Metabolic crisis was not observed during the follow-up period. In addition, no patient showed progression of severe renal impairment requiring hemodialysis. Progression of delayed cognitive development was not observed. Social functioning with improved neuropsychiatric development was observed. Conclusion This study showed that LDLT achieved improved quality of life with less restrictive diet, therefore it could be a feasible alternative option to DDLT for the treatment of patients with MMA, even with an auxiliary LT.