Impact of Initial Vancomycin Trough Concentration on Clinical and Microbiological Outcomes of Methicillin-Resistant Staphylococcus aureus Bacteremia in Children

Vancomycin Dosing and Its Association With Acute Kidney Injury in Pediatric Cardiac Intensive Care Patients Under 3 Months of Age

BACKGROUND

The standard vancomycin regimen for term neonates is 45 mg/kg/day. However, the optimal starting vancomycin dosing for achieving therapeutic levels in young infants in cardiac intensive care units remains unknown. Moreover, data on the association of supratherapeutic vancomycin levels with acute kidney injury (AKI) are limited.

METHODS

Retrospective study of infants ≤3 months old, receiving vancomycin following congenital heart surgery at postoperative intensive care unit admission. Assessed were vancomycin dosing, achievement of therapeutic trough concentration of 10-20 mg/L and development of AKI, based on the modified Kidney Disease Improving Global Outcomes criteria.

RESULTS

Inclusion criteria were met by 109 patients with a median age of 8 days (IQR: 6-16). The mean (SD) vancomycin dose required for achieving therapeutic concentration was 28.9 (9.1) mg/kg at the first postoperative day. Multivariate logistic regression identified higher preoperative creatinine levels and shorter cardiopulmonary bypass time as predictors of supratherapeutic vancomycin concentrations (c-index 0.788). During the treatment course, 62 (56.9%) developed AKI. Length of stay and mortality were higher in those who developed AKI as compared with those who did not. Multivariate logistic regression identified higher vancomycin concentration as a predictor for postoperative AKI, OR, 3.391 (95% CI: 1.257-9.151), P = 0.016 (c-index 0.896).

CONCLUSION

Our results support a lower starting vancomycin dose of ~30 mg/kg/day followed by an early personalized therapeutic approach, to achieve therapeutic trough concentrations of 10-20 mg/L in cardiac postoperative term infants. Supratherapeutic concentrations are associated with an increased risk for AKI, which is prevalent in this population and associated with adverse outcomes.

Comparison of Vancomycin Trough-Based and 24-Hour Area Under the Curve Over Minimum Inhibitory Concentration (AUC/MIC)-Based Therapeutic Drug Monitoring in Pediatric Patients

OBJECTIVES

Vancomycin 24-hour area under the curve over minimum inhibitory concentration (AUC/MIC) monitoring has been recommended over trough-based monitoring in pediatric patients. This study compared the proportion of target attainment between vancomycin AUC/MIC and trough-based methods, and identified risk factors for subtherapeutic initial extrapolated targets.

METHODS

This was a retrospective, observational study conducted at KK Women's and Children's Hospital (KKH), Singapore. Patients aged 1 month to 18 years with stable renal function who received intravenous vancomycin between January 2014 and October 2017, with at least 2 vancomycin serum concentrations obtained after the first dose of vancomycin, were included. Using a pharmacokinetic software, namely Adult and Pediatric Kinetics (APK), initial extrapolated steady-state troughs and 24-hour AUC were determined by using a one-compartmental model. Statistical tests included Wilcoxon rank sum test, McNemar test, logistic regression, and classification and regression tree (CART) analysis.

RESULTS

Of the 82 pediatric patients included, a significantly larger proportion of patients achieved therapeutic targets when the AUC/MIC-based method (24, 29.3%) was used than with the trough-based method (9, 11.0%; p < 0.01). Patients with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 or with age <13 years had an increased risk of obtaining subtherapeutic targets. However, empiric vancomycin doses of 60 mg/kg/day would be sufficient to achieve serum therapeutic targets, using the AUC/MIC-based method.

CONCLUSION

The AUC/MIC-based vancomycin monitoring may be preferred because a larger proportion of patients could achieve initial therapeutic targets. Future prospective studies with larger sample size will be required to determine the optimal vancomycin strategy for pediatric patients.

Evaluation of Vancomycin TDM Strategies: Prediction and Prevention of Kidney Injuries Based on Vancomycin TDM Results

The current guidelines for therapeutic drug monitoring (TDM) of vancomycin suggest a target 24-hour area under the curve (AUC_0-24) of 400 to 600 mg*h/L for serious methicillin-resistant Staphylococcus aureus infections. In this study, the predictabilities of acute kidney injury (AKI) of various TDM target parameters, target levels, and sampling methods were evaluated in patients who underwent TDM from January 2020 to December 2020. The AUC_0-24 and trough values were calculated by both one- and two-point sampling methods, and were evaluated for the predictability of AKI. Among the AUC_0-24 cutoff comparisons, the threshold value of 500 mg*h/L in the two sampling methods was statistically significant (P = 0.042) when evaluated for the predictability of AKI. Analysis by an receiver operating characteristic curve estimated an AUC_0-24 cutoff value of 563.45 mg*h/L as a predictor of AKI, and was proposed as the upper limit of TDM target.

Relationship between Vancomycin Trough Serum Concentrations and Clinical Outcomes in Children: a Systematic Review and Meta-Analysis

To systematically evaluate the relationships between vancomycin trough serum concentrations and clinical outcomes in children using meta-analysis. Several databases, including PubMed, Elsevier, Web of Science, EMBASE, Medline, clinicaltrials.gov, the Cochrane Library, and three Chinese databases (Wanfang Data, China National Knowledge Infrastructure, and SINOMED), were comprehensively searched to obtain research articles on vancomycin use in children from inception through December 2021. All studies were screened and evaluated using the Cochrane systematic review method. Then, the feature information was extracted for meta-analysis. The evaluated results included clinical efficacy, vancomycin-associated nephrotoxicity, hepatotoxicity, ototoxicity, mortality, and microbial clearance. A total of 35 studies involving 4820 children were included in the analysis. The meta-analysis showed that compared with children with vancomycin trough concentrations <10 μg/mL, those with vancomycin trough concentrations ≥10 μg/mL had a higher clinical efficacy rate [OR: 2.23, 95% CI: 1.29 to 3.84, P = 0.004] and higher incidences of nephrotoxicity [OR: 2.76, 95% CI: 1.51 to 5.07, P = 0.001], ototoxicity [OR: 1.87, 95% CI: 1.08 to 3.23, P = 0.02] and microbial clearance [OR: 2.36, 95% CI: 1.53 to 3.64, P = 0.0001]. All-cause mortality [OR: 1.07, 95% CI: 0.45 to 2.53, P = 0.88] and hepatotoxicity [OR: 0.84, 95% CI: 0.46 to 1.53, P = 0.57] were similar between the two groups. Subgroup analysis showed that compared with children with vancomycin trough concentrations of 10 to 15 μg/mL, those with vancomycin trough concentrations >15 μg/mL had a higher incidence of nephrotoxicity [OR: 2.64, 95% CI: 1.28 to 5.43, P = 0.008], but there was no significant difference in clinical efficacy [OR: 0.85, 95% CI: 0.30 to 2.44, P = 0.76]. A vancomycin trough concentration of 10 to 15 μg/mL can improve clinical efficacy in children. Additionally, avoidance of trough concentrations >15 μg/mL can reduce the incidence of adverse reactions.

Clinical Response and Hospital Costs of Therapeutic Drug Monitoring for Vancomycin in Elderly Patients

Cost-effectiveness analysis has been widely used to assess and compare the costs and benefits of a clinical service. The cost-effectiveness of vancomycin therapeutic drug monitoring (TDM) has not been studied in the elderly, who are susceptible to vancomycin-induced adverse effects. This study was performed to evaluate if vancomycin TDM is cost-effective in elderly patients in the Republic of Korea. Using the electronic medical records at a tertiary university hospital, we performed a retrospective observational study to evaluate the cost-effectiveness of vancomycin TDM in 850 elderly patients who underwent vancomycin TDM with an appropriate, recommended dosing regimen and 1094 elderly patients who did not. Cost-effectiveness variables such as clinical outcomes and medical expenses were evaluated using univariate and multivariate analyses. The TDM group spent significantly less than the non-TDM group per patient for total medical expenses (by USD 841.40) and medication expenses (by USD 16.70). However, no significant difference was noted between the TDM and non-TDM groups in clinical outcomes such as microbiological cure, prevention of nephrotoxicity, or reduced mortality, irrespective of admission to the intensive care unit. Vancomycin TDM in elderly patients was associated with economic benefits, but not with better clinical outcomes.

Association of Initial Trough Concentrations of Vancomycin with Outcomes in Pediatric Patients with Gram-Positive Bacterial Infection

Vancomycin is a glycopeptide antibiotic used for the treatment of Gram-positive infections. For adult patients, treatment with vancomycin requires effective therapeutic drug-monitoring (TDM) to achieve clinical outcomes and reduce the incidence of adverse effects. However, it remains still unclear whether the TDM with vancomycin is beneficial in yielding better clinical outcomes in pediatrics. The objective of our study was to evaluate whether the clinical response to treatment was associated with initial trough concentrations of vancomycin in pediatric patients. A retrospective observation study of 60 patients (age: 1 month-15 years) who had completed and qualified for analysis was conducted at Kyoto University Hospital. The response to treatment was assessed by the time to resolution of fever and time to 50% decline in C-reactive protein (CRP). In addition, we explored whether vancomycin trough level was associated with the baseline characteristics. Trend analysis showed that there were significant correlations between vancomycin trough level and age, body weight, estimated glomerular filtration rate, and serum albumin levels. The time to resolution of fever of the patients with higher initial trough level (≥ 5 µg/mL) was significantly lower than that of the patients with lower trough level (< 5 µg/mL). The higher vancomycin concentration tended to be associated with the shorter time to 50% decline in CRP. The findings suggest that initial trough concentration is important in achieving better outcomes with vancomycin treatment in pediatrics.

Systematic review and meta-analysis to explore optimal therapeutic range of vancomycin trough level for infected paediatric patients with Gram-positive pathogens to reduce mortality and nephrotoxicity risk

The aim of this study was to investigate the association between vancomycin trough level and clinical outcomes (mortality and nephrotoxicity) among infected paediatric patients with Gram-positive pathogens. We systematically searched the Scopus, EMBASE, Cochrane Central Register of Controlled Trials, PubMed and CINAHL databases up to March 2020. A total of seven retrospective cohort or case-control studies were included to compare clinical effects and safety: three studies set the threshold of vancomycin trough level at 10 mg/L and the others set it at 15 mg/L. Our analysis showed that vancomycin trough level of 10-15 mg/L was associated with significantly lower mortality [<10 mg/L vs. ≥10 mg/L, odds ratio (OR) = 3.21, 95% confidence interval (CI) 1.74-5.91; and <15 mg/L vs. ≥15 mg/L, OR = 0.31, 95% CI 0.10-0.95). The high vancomycin trough group (≥10 mg/L or ≥15 mg/L) showed a higher incidence of nephrotoxicity (<10 mg/L vs. ≥10 mg/L, OR = 0.06, 95% CI 0.03-0.12; and <15 mg/L vs. ≥15 mg/L, OR = 0.28, 95% CI 0.12-0.65). This is the first meta-analysis to reveal the optimal therapeutic range of vancomycin trough level in children. Our findings strongly suggest a superior benefit of vancomycin trough of 10-15 mg/L for paediatric patients.

Pediatric Antibiotic Stewardship: Optimization of Vancomycin Therapy Based on Individual Pharmacokinetics

BACKGROUND

Vancomycin has been a first-line treatment for Gram-positive infections for decades. However, strategies for therapeutic drug monitoring (TDM) and dose-optimization in pediatrics remain controversial. In this study, we analyzed the impact of specific antibiotic stewardship interventions on efficacy and safety of vancomycin therapy.

METHODS

From September 2014 to May 2017, we conducted a prospective study to compare a control and a TDM intervention group in our tertiary care center. As part of an antibiotic stewardship program, we implemented internal guidelines on correct vancomycin dosing, TDM timing, as well as targeted trough level range and installed a pharmacokinetic (PK) consultation service to adapt vancomycin dosing to individually calculated PK parameters. As primary clinical outcomes, the percentage of patients with sustained therapeutic vancomycin trough levels and treatment days with therapeutic vancomycin trough levels, that is, 10-15 mg/L were analyzed. Secondary outcomes included nephrotoxicity, readmission rate and mortality. Median daily dose required to achieve therapeutic trough levels was examined.

RESULTS

Clinical outcomes for 90 control patients were compared with outcomes for 19 patients guided by a PK consultation service. Percentage of patients with sustained therapeutic vancomycin trough levels increased from 17.8% to 94.7% (P < 0.001) and percentage of treatment days with therapeutic vancomycin trough levels increased from 18.4% (117/637) to 665% (155/233, P < 0.001). Readmission rate decreased from 24.4% to 5.3% (P = 0.07). No differences in nephrotoxicity or mortality rate were observed between groups. A median daily dose of 72 mg/kg/d was required to achieve therapeutic trough levels.

CONCLUSIONS

Our data demonstrate that implementation of internal guidelines and a PK consultation service was associated with a profound improvement of vancomycin therapy and, therefore, patient safety.

Impact of initial vancomycin pharmacokinetic/pharmacodynamic parameters on the clinical and microbiological outcomes of methicillin-resistant Staphylococcus aureus bacteremia in children

Optimal vancomycin exposure is important to minimize treatment failure of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. We aimed to analyze the impact of initial vancomycin pharmacokinetic/pharmacodynamic (PK/PD) parameters, including the initial vancomycin C trough and the area under the curve (AUC)/minimal inhibitory concentration (MIC) on the outcomes of pediatric MRSA bacteremia. The study population consisted of hospitalized children aged between 2 months and 18 years with MRSA bacteremia, in whom C trough was measured at least one time within the time period of January 2010 to March 2018. Demographic profiles, underlying diseases, and clinical/microbiological outcomes were abstracted retrospectively. During the study period, 73 cases of MRSA bacteremia occurred in children with a median age of 12.4 months. Severe clinical outcomes leading to intensive care unit stay and/or use of mechanical ventilation occurred in 47.5% (35/73); all-cause 30-day mortality was 9.7% (7/72). The median dosage of vancomycin was 40.0 mg/kg/day. There was a weak linear relationship between C trough and the corresponding AUC/MIC (r = 0.235). ROC curves for achieving an AUC/MIC of 300 suggested that the initial C trough at 10 μg/mL could be used as a cut-off value with a sensitivity of 90.5% and a specificity of 44%. Although persistent bacteremia at 48-72 hours after vancomycin administration was observed more frequently when the initial C trough was < 10 μg/mL and initial AUC/MIC was < 300, initial AUC/MIC < 300 was the only risk factor associated with persistent bacteremia at 48-72 hours (adjusted OR 3.05; 95% CI, 1.07-8.68). Initial C trough and AUC/MIC were not associated with 30-day mortality. Although there was a weak relationship between C trough and AUC/MIC, initial AUC/MIC < 300 could be used as a predictor of persistent MRSA bacteremia at 48-72 hours. Further prospective data on optimal vancomycin dosing are necessary to improve clinical and microbiological outcomes in pediatric MRSA bacteremia.

Target Attainment and Clinical Efficacy for Vancomycin in Neonates: Systematic Review

Vancomycin is commonly used as a treatment for neonatal infections. However, there is a lack of consensus establishing the optimal vancomycin therapeutic regimen and defining the most appropriate PK/PD parameter correlated with the efficacy. A recent guideline recommends AUC–guided therapeutic dosing in treating serious infections in neonates. However, in clinical practice, trough serum concentrations are commonly used as a surrogate PKPD index for AUC24. Despite this, target serum concentrations in a neonatal population remain poorly defined. The objective is to describe the relationship between therapeutic regimens and the achievement of clinical or pharmacokinetic outcomes in the neonatal population. The review was carried out following PRISMA guidelines. A bibliographic search was manually performed for studies published on PubMed and EMBASE. Clinical efficacy and/or target attainment and the safety of vancomycin treatment were evaluated through obtaining serum concentrations. A total of 476 articles were identified, of which 20 met the inclusion criteria. All of them evaluated the target attainment, but only two assessed the clinical efficacy. The enormous variability concerning target serum concentrations is noteworthy, which translates into a difficulty in determining which therapeutic regimen achieves the best results. Moreover, there are few studies that analyze clinical efficacy results obtained after reaching predefined trough serum concentrations, this information being essential for clinical practice.

A Moving Target-Vancomycin Therapeutic Monitoring

Therapeutic drug monitoring (TDM) has been a common practice to optimize efficacy and safety of vancomycin. While vancomycin trough-only TDM has widely been integrated into pediatric clinical practice since 2009, recently updated vancomycin TDM guidelines published in March 2020 recommend area under the curve (AUC) based TDM for vancomycin instead of trough-only TDM. In this review, we discuss the rationale behind the change in TDM recommendations, describe two approaches for calculating vancomycin AUC in clinical practice, and address considerations for integrating vancomycin AUC TDM into pediatric clinical practice. Our primary goal is to provide pediatric clinicians with a resource for implementing vancomycin AUC monitoring into clinical care.

Intravenous Vancomycin Therapeutic Drug Monitoring in Children: Evaluation of a Pharmacy-Driven Protocol and Collaborative Practice Agreement

BACKGROUND

Vancomycin optimization is challenging, requiring careful therapeutic drug monitoring (TDM) to avoid toxicity and ensure an efficacious concentration. Most prescriptions are empiric and often discontinued within 72 hours, which makes early TDM unnecessary. Although TDM using trough levels is common, the area under the concentration-time curve (AUC) is the preferred pharmacodynamic target. We studied the effect of a pharmacy-driven vancomycin collaborative practice agreement (CPA) at a children's hospital that delayed TDM up to 72 hours and targeted a 2-point 24-hour AUC of ≥400 mg × h/L.

METHODS

We retrospectively reviewed vancomycin courses in patients aged ≥30 days who received vancomycin between April 1, 2011, and August 30, 2017. We implemented the CPA on June 1, 2014. Outcomes included CPA use, use of TDM, dosage adjustments, and development of acute kidney injury; we compared courses given while monitoring only trough levels (TO-TDM) with those given while using the CPA (AUC-TDM). We performed interrupted time series analyses to account for preintervention trends.

RESULTS

We included 2379 courses in the TO-TDM period and 2155 in the AUC-TDM period. During AUC-TDM, 87% of the courses were managed by the CPA. In adjusted interrupted time series analyses, CPA implementation was associated with an initial change in level of -0.265 (95% confidence interval [CI], -0.336 to -0.189) TDM and an initial change in level of -0.332 (95% CI, -0.506 to -0.163) dosage adjustments. The 1-year risk of acute kidney injury decreased after CPA implementation (odds ratio, 0.695 [95% CI, 0.539-0.91]).

CONCLUSION

The pharmacy-driven vancomycin CPA resulted in less monitoring and fewer dose adjustments without increasing AKI.

Effect of Vancomycin Loading Doses on the Attainment of Target Trough Concentrations in Hospitalized Children

OBJECTIVE

Subtherapeutic vancomycin trough concentrations are common in children and may be associated with suboptimal therapeutic response. Our objective was to determine if vancomycin loading doses safely increase the frequency of target trough attainment in hospitalized children.

METHODS

Patients (≥6 months and <18-years-old) who received a vancomycin loading dose between February 1, 2018, and January 30, 2019, were retrospectively enrolled. These patients were compared to a convenience cohort of patients hospitalized between January 1, 2015, and December 31, 2015, who received vancomycin without a loading dose. Target trough concentrations were defined as >15 mg/dL for invasive infections and >10 mg/dL for non-invasive infections.

RESULTS

A total of 151 patients were enrolled, with 77 in the control arm and 74 in the loading dose arm. There was no significant difference in the frequency of comorbidities or need for intensive care unit admission between the two arms. Those receiving a vancomycin loading dose were older (mean age 9.1 vs 5.2 years, p < 0.0001). Patients given a loading dose achieved higher mean initial trough values (13.0 mg/dL vs 9.2 mg/dL, p < 0.0001), were more likely to have an initial trough at or above target (37.0% vs 10.4%, p = 0.0001), were more likely to reach target trough values at any point during therapy (52.1% vs 32.9%, p = 0.0081), and attained a target trough concentration more quickly (mean 41.1 hours vs 58.8 hours, p = 0.0118). There were no significant differences in the frequency of serum creatinine elevation or oliguria at the end of therapy.

CONCLUSIONS

Vancomycin loading doses may improve the ability to safely obtain target trough values in hospitalized children.

Vancomycin therapeutic drug monitoring in paediatrics

AIM

Vancomycin guidelines for therapeutic drug monitoring (TDM) aim to maximise efficacy while minimising toxicity and resistance. Vancomycin is effective against Staphylococcus aureus when it achieves area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC) > 400. Studies in children have shown that target trough concentrations poorly correlate to AUC/MIC > 400; however, they are used in practice for clinical convenience. This review in paediatric inpatients aims to audit performance against TDM guidelines and consider what changes are needed to optimise vancomycin monitoring.

METHODS

Vancomycin prescriptions in patients younger than 18 years old were collected over a 15-month period. Primary outcome measures were vancomycin initial dose (mg/kg/day) and the timing and result of first trough concentration (mg/L). Secondary outcome measures were the numbers achieving recommended targets and whether appropriate dose adjustments were made in response to TDM.

RESULTS

A total of 133 courses reached the time when TDM should occur. Average patient age was 6.5 years, and the average initial dose was 52.55 mg/kg/day (range 19.05-86.54 mg/kg). Only 25% of courses (n = 34) had a trough concentration measured at the recommended time. The mean trough concentration was 11.6 mg/L (range < 2.0-39.7). Of 40 patients with a low trough concentration, 50% continued without dose adjustment.

CONCLUSION

As shown in the literature, there is a poor correlation between the vancomycin dose given and the trough concentration achieved. Given that recommendations for trough concentration monitoring are designed to simplify the process yet are poorly adhered to, a strategic plan to address these issues is needed.

Vancomycin drug monitoring in infants with CoNS sepsis-target attainment, microbiological response and nephrotoxicity

OBJECTIVES

To characterize residual vancomycin concentrations (Cmin) and assess the relationships between Cmin, the risk of nephrotoxicity and persistent CoNS sepsis.

METHODS

In this 5-year retrospective study among infants treated with vancomycin, the primary outcome was the proportion of those with a steady state Cmin between 10 and 20 mg/L. The secondary outcomes were nephrotoxicity and persistent CoNS sepsis.

RESULTS

Of 120 infants included, the median first steady state Cmin was 12.4 mg/L and 77 (64%) had a Cmin between 10 and 20 mg/L. Six percent developed nephrotoxicity. This risk was not associated with Cmin. Of the 30 infants with CoNS sepsis, 17 (57%) had persistent bacteremia, and this risk did not correlate significantly with Cmin, CoNS minimal inhibitory concentration (MIC) for vancomycin, or Cmin/MIC.

CONCLUSIONS

The majority of infants achieved targeted levels of vancomycin, but persistent bacteremia was common. We did not identify a Cmin threshold associated with nephrotoxicity, nor with microbiological clearance.

Vancomycin Treatment Failure in Children With Methicillin-Resistant Staphylococcus aureus Bacteremia

OBJECTIVES

Limited data exist regarding clinical outcomes of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in children treated with vancomycin. Treatment success in adults correlates best with an area under the curve/minimum inhibitory concentration (AUC₂₄/MIC) ratio ≥400. It is unknown if this relationship is useful in children.

METHODS

Charts of children who received vancomycin ≥5 days for MRSA bacteremia with a steady state trough were reviewed. AUC₂₄/MIC ratios were estimated using 2 different vancomycin clearance equations. Vancomycin treatment failure was defined as persistent bacteremia ≥7 days, recurrent bacteremia within 30 days, or 30-day mortality.

RESULTS

There were 67 bacteremia episodes in 65 patients. Nine (13.4%) met failure criteria: persistent bacteremia (n = 6), recurrent bacteremia (n = 2), 30-day mortality (n = 1). There were no differences between patients receiving <60 mg/kg/day and ≥60 mg/kg/day of vancomycin in median trough (11.9 versus 12.3 mg/L, p = 0.1). Troughs did not correlate well with AUC₂₄/MIC ratios (R ² = 0.32 and 0.22). Patients receiving ≥60 mg/kg/day had greater probability of achieving ratios ≥400. There were no significant differences in median dose (p = 0.8), trough (p = 0.24), or AUC₂₄/MIC ratios (p = 0.07 and p = 0.6) between patients with treatment success and failure.

CONCLUSIONS

Treatment failure was lower than previously reported in children. AUC₂₄/MIC ratios ≥400 were frequently achieved but were not associated with treatment success, dose, or troughs. Prospective studies using standard definitions of vancomycin treatment failure are needed to understand treatment failure in children with MRSA bacteremia.

Optimizing Vancomycin Use Through 2-Point AUC-Based Therapeutic Drug Monitoring in Pediatric Patients

The 24-hour vancomycin area under the serum concentration-time curve (AUC₂₄ ) divided by the minimum inhibitory concentration (MIC) (AUC₂₄ /MIC) is more closely related to patient outcomes than serum trough concentrations (C_trough ). Two-point simplified equations for calculating AUC based on serum peak concentrations (C_peak ) and C_trough , named equation A (EqA) and equation B (EqB), have recently been adopted into clinical use for adult pediatric patients. We aimed to find the agreement between predicted AUC₂₄ using the reference method (ref) relative to EqA and EqB and the correlation between C_trough and AUC₂₄ . From June to December 2018, 43 pediatric patients with normal renal function, receiving 15 mg/kg of vancomycin intravenously every 6 hours, were enrolled. The pediatric patients' median age was 2.2 years (range 0.1-15.3). At steady state, vancomycin C_peak and C_trough were measured at 2 hours after infusion completion and within 30 minutes before the next dosing, respectively. AUC₂₄ was estimated using ref, EqA, and EqB. From Bland-Altman analysis, the 2 AUC₂₄ s estimated by ref and EqA showed less bias than those estimated by ref and EqB (bias 1.3 and -72.1 mg⋅h/L, respectively). C_trough and AUC₂₄ using either ref or EqA were correlated more closely (r² = 0.94) than with EqB (r² = 0.86). Assuming a vancomycin MIC of 1 mg/L, an AUC₂₄ ≥400 mg⋅h/L was targeted. Regardless of the method used, AUC₂₄ ≥400 mg⋅h/L was never seen with C_trough <8 mg/L but was always seen with C_trough >10 mg/L. In conclusion, EqA based on the 2 measured serum concentrations was sufficiently accurate for AUC₂₄ estimation. C_trough >10 mg/L correlated highly to AUC₂₄ ≥400 mg⋅h/L.

Association Between Vancomycin Trough Concentrations and Duration of Methicillin-Resistant Staphylococcus aureus Bacteremia in Children

In a multicenter retrospective study, we sought to determine the optimal vancomycin trough concentration that would impact the duration of methicillin-resistant Staphylococcus aureus bacteremia in children. We found that a median vancomycin trough concentration of <10 µg/mL within the first 72 hours may be associated with a longer duration of bacteremia compared to a median trough concentration of ≥10 µg/mL.

Empirical Vancomycin Dosing in Pediatric Patients with Congenital Heart Disease and the Impact of Cardiopulmonary Bypass on Trough Concentrations

OBJECTIVES

To determine the optimal vancomycin dosing regimen to achieve empirical goal trough concentrations in pediatric patients with congenital heart disease and to examine the impact of cardiopulmonary bypass on vancomycin dosing requirements.

METHODS

Patients younger than 18 years admitted to the pediatric cardiovascular intensive care unit (CVICU) at our institution from October 1, 2012-December 31, 2014, who received at least one dose of vancomycin, were reviewed retrospectively. Included patients had a steady-state vancomycin trough concentration drawn during the study period. The first steady-state vancomycin trough drawn after being initiated on empirical vancomycin therapy was analyzed for each patient. Excluded patients were those who received mechanical circulatory support, any form of renal replacement therapy, or had a serum creatinine result greater than 1.0 mg/dl on the day of vancomycin initiation.

RESULTS

Overall, 77 patients met inclusion criteria, of which 57.1% had undergone cardiopulmonary bypass (CPB) before CVICU admission. Median age was 62 days (interquartile range [IQR] 8.3-176 days). Median daily vancomycin dose was 36.25 mg/kg/day (IQR 29-40 mg/kg/day), resulting in a median steady-state trough of 10.0 μg/ml (IQR 6.3-12.9 μg/ml). Therapeutic troughs occurred in 50.6% of patients; supratherapeutic and subtherapeutic concentrations were attained in 18.2% and 31.2% of patients, respectively. A subgroup analysis of patients who were post-CPB revealed that the only additional variable to affect vancomycin trough concentrations was aortic cross-clamp time (median 56 min, IQR 0-123.3 min, p=0.02).

CONCLUSIONS

Empirical vancomycin dosing to achieve troughs of 8-15 μg/dl in patients with congenital heart disease without evidence of significant acute kidney injury should be 30 mg/kg/day for neonates, 35-40 mg/kg/day for infants, and 45 mg/kg/day in children, with adjustments required for patients with elevated creatinine or significant aortic cross-clamp time. The receipt and duration of CPB did not affect total daily vancomycin dose requirements.