Vancomycin-induced nephrotoxicity: mechanism, incidence, risk factors and special populations. A literature review

Vancomycin induces reactive oxygen species-dependent apoptosis via mitochondrial cardiolipin peroxidation in renal tubular epithelial cells

Vancomycin (VCM) is a first-line antibiotic for serious infections caused by methicillin-resistant Staphylococcus aureus. However, nephrotoxicity is one of the most complaint in VCM therapy. We previously reported that VCM induced apoptosis in a porcine proximal tubular epithelial cell line (LLC-PK1), in which mitochondrial complex I may generate superoxide, leading to cell death. In the present study, VCM caused production of mitochondrial reactive oxygen species and peroxidation of the mitochondrial phospholipid cardiolipin that was reversed by administration of the mitochondrial uncoupler carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP). FCCP also significantly suppressed VCM-induced depolarization of the mitochondrial membrane and apoptosis. Moreover, the lipophilic antioxidant vitamin E and a mitochondria-targeted antioxidant, mitoTEMPO, also significantly suppressed VCM-induced depolarization of mitochondrial membrane and apoptosis, whereas vitamin C, n-acetyl cysteine, or glutathione did not provide significant protection. These findings suggest that peroxidation of the mitochondrial membrane cardiolipin mediated the VCM-induced production of intracellular reactive oxygen species and initiation of apoptosis in LLC-PK1 cells. Furthermore, regulation of mitochondrial function using a mitochondria-targeted antioxidant, such as mitoTEMPO, may constitute a potential strategy for mitigation of VCM-induced proximal tubular epithelial cell injury.

Drug-associated acute kidney injury: who's at risk?

The contribution of nephrotoxic medications to the development of acute kidney injury (AKI) is becoming better understood concomitant with the increased incidence of AKI in children. Treatment of AKI is not yet available, so prevention continues to be the most effective approach. There is an opportunity to mitigate severity and prevent the occurrence of AKI if children at increased risk are identified early and nephrotoxins are used judiciously. Early detection of AKI is limited by the dependence of nephrologists on serum creatinine as an indicator. Promising new biomarkers may offer early detection of AKI prior to the rise in serum creatinine. Early detection of evolving AKI is improving and offers opportunities for better management of nephrotoxins. However, the identification of patients at increased risk will remain an important first step, with a focus on the use of biomarker testing and interpretation of the results.

Intravenous Vancomycin Dosing in the Elderly: A Focus on Clinical Issues and Practical Application

The elderly population can be divided into three distinct age groups: 65-74 years (young-old), 75-84 years (middle-old), and 85+ years (old-old). Despite evidence of a shift in leading causes for mortality in the elderly from infectious diseases to chronic conditions, infections are still a serious cause of death in this population. These patients are at increased risk due to weakened immune systems, an increased prevalence of underlying comorbidities, and decreased physiologic reserves to fight infection. Additionally, elderly patients, especially adults in institutional settings, are at an increased risk of colonization and subsequent infection with methicillin-resistant Staphylococcus aureus at a rate that is five times higher than in younger individuals, causing an increase in empiric and definitive vancomycin use. Elderly patients have unique characteristics that make dosing vancomycin a challenge for clinicians, such as increased volume of distribution and decreased renal function. Using the best available evidence, it is recommended to initiate lower empiric maintenance doses and monitor vancomycin serum concentrations earlier than steady state to accurately calculate drug elimination and make appropriate dose adjustments.

A Population Pharmacokinetic Model for Vancomycin in Adult Patients Receiving Extracorporeal Membrane Oxygenation Therapy

The literature on the pharmacokinetics of vancomycin in patients undergoing extracorporeal membrane oxygenation (ECMO) therapy is sparse. A population pharmacokinetic (PK) model for vancomycin in ECMO patients was developed using a nonlinear mixed effects modeling on the concentration–time profiles of 14 ECMO patients who received intravenous vancomycin. Model selection was based on log‐likelihood criterion, goodness of fit plots, and scientific plausibility. Identification of covariates was done using a full covariate model approach. The pharmacokinetics of vancomycin was adequately described with a two‐compartment model. Parameters included clearance of 2.83 L/hr, limited central volume of distribution 24.2 L, and low residual variability 0.67%. Findings from the analysis suggest that standard dosing recommendations for vancomycin in non‐ECMO patients are adequate to achieve therapeutic trough concentrations in ECMO patients. This further shows that ECMO minimally affects the PK of vancomycin in adults including in higher‐weight patients.

Enigma: infection or allergy? Vancomycin-induced DRESS syndrome with dialysis-dependent renal failure and cardiac arrest

A man aged 73 years with infective endocarditis presented with septic shock and was started on immediate antimicrobial therapy. His blood culture yielded no organism. Subsequently, he developed a severe allergic reaction to prolonged empirical vancomycin therapy. This manifested as fever, widespread maculopapular rash and severe progressive acute kidney injury ultimately requiring dialysis. In the context of eosinophilia, this was determined to be drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Deciphering this complication as allergy in the context of severe infection required extreme caution due to the polarity of treatment with immunosuppression. Ultimately, this was used, with improvement of renal function, resolution of symptoms and absence of recurrence of infection. In summary, we present a case of vancomycin-related DRESS syndrome leading to dialysis-which is unique in the literature-complicating the treatment of culture-negative infective endocarditis.

Prospective Comparison of Acute Kidney Injury During Treatment With the Combination of Piperacillin-Tazobactam and Vancomycin Versus the Combination of Cefepime or Meropenem and Vancomycin

PURPOSE

To prospectively evaluate the observed incidence of acute kidney injury (AKI) in adult patients receiving the combination of piperacillin-tazobactam and vancomycin versus the combination of cefepime or meropenem and vancomycin for greater than 72 hours.

METHODS

This was a prospective, open-label cohort study at a community academic medical center involving adult patients over a 3-month time period who received either the combination of piperacillin-tazobactam and vancomycin or the combination of cefepime or meropenem and vancomycin for greater than 72 hours. The patients were evaluated for AKI, defined using specific criteria introduced by Kidney Disease: Improving global outcomes (KDIGO) acute kidney injury work group in 2012.

RESULTS

A total of 85 patients receiving either antimicrobial combination were evaluated for AKI. The incidence of AKI was significantly higher in the piperacillin-tazobactam and vancomycin group (37.3%) compared with the cefepime or meropenem and vancomycin group (7.7%; χ² = 7.80, P = .005).

CONCLUSION

The result of this study suggests that the risk of developing AKI is increased in patients receiving the combination of piperacillin-tazobactam and vancomycin versus those receiving the combination of cefepime or meropenem and vancomycin.

Review of vancomycin-induced renal toxicity: an update

In recent times the use of larger doses of vancomycin aimed at curbing the increasing incidence of resistant strains of Staphylococcus aureus has led to a wider report of acute kidney injury (AKI). Apart from biological plausibility, causality is implied by the predictive association of AKI with larger doses, longer duration, and graded plasma concentrations of vancomycin. AKI is more likely to occur with the concurrent use of nephrotoxic agents, and in critically ill patients who are susceptible to poor renal perfusion. Although most vancomycin-induced AKI cases are mild and therefore reversible, their occurrence may be associated with greater incidence of end-stage kidney disease and higher mortality rate. The strategy for its prevention includes adequate renal perfusion and therapeutic drug monitoring in high-risk individuals. In the near future, there is feasibility of renoprotective use of antioxidative substances in the delivery of vancomycin.

A propensity-matched cohort study of vancomycin-associated nephrotoxicity in neonates

BACKGROUND

The incidence of nephrotoxicity among vancomycin-treated neonates has been reported to range from 2% to 20%. These widely varying estimates have led to confusion and controversy regarding the safety of vancomycin among neonates.

OBJECTIVE

Evaluate the incidence of nephrotoxicity among neonates receiving vancomycin concomitantly with gentamicin.

DESIGN

Retrospective observational cohort study using propensity score matching to provide covariate balance between neonates who did or did not receive vancomycin based on factors known to be related to the development of renal dysfunction.

SETTING

Hospitals (n=22) throughout the Intermountain West, including a quaternary care children's hospital.

PATIENTS

Neonates ≤44 postmenstrual weeks (median gestational age: 31 (IQR 28-36) weeks) receiving intravenous gentamicin with or without exposure to vancomycin from January 2006 to December 2012.

MAIN OUTCOME MEASURES

Nephrotoxicity based on the modified Acute Kidney Injury Network criteria for acute kidney injury (AKI) or serum creatinine concentration ≥1.5 mg/dL persisting for ≥48 h.

RESULTS

The final cohort was comprised of 1066 neonates (533 receiving vancomycin and gentamicin vs 533 receiving gentamicin). In a propensity score-matched cohort that was well balanced across 16 covariates, AKI was not associated with vancomycin use (16 neonates receiving vancomycin vs 7 controls experienced AKI; OR 1.5; 95% CI 0.6 to 4.0). However, the presence of a patent ductus arteriosus, concomitant non-steroidal anti-inflammatory drug use, ≥1 positive blood cultures, low birth weight and higher severity of illness and risk of mortality scores were associated with an increased risk of nephrotoxicity.

CONCLUSIONS

These results corroborate several earlier reports and much anecdotal evidence describing the infrequent occurrence of nephrotoxicity in neonates receiving concomitant vancomycin and gentamicin.

Vancomycin dosing nomograms targeting high serum trough levels in different populations: pros and cons

PURPOSE

Utilization of higher doses of vancomycin to achieve the trough concentrations of 15-20 mg/L for complicated infections has been recommended by the Infectious Diseases Society of America clinical practice guideline in recent years. Concerning this recommendation, several nomograms have been constructed targeting this optimal trough level range in different populations of patients. In this review, we have collected available nomograms targeting high trough serum levels of vancomycin, particularly comparing their advantages and limitations.

METHOD

The data were collected by searching Scopus, PubMed, Google scholar, Medline, and Cochrane database systematic reviews. The key words used as search terms were "vancomycin", "high trough level", "dosing nomogram", "dosing strategy", "neonates", "critically ill", "pediatrics", and "hemodialysis". We have included 17 related human studies published up to the date of this publication.

RESULTS & CONCLUSION

Most of the available nomograms have determined the doses according to body weight and renal function. Their initial predicting success rate were 44-76 % for non-critically ill patients, 42-84 % for critically ill patients, 54 % for one nomogram specially designed for hemodialysis patients, and 71 % for the only nomogram developed for neonates. Based on validation studies, in most of cases, using a vancomycin dosing nomogram significantly improved and accelerated achievement of target trough concentrations. However, it should be noted that there are limited data about patients' clinical and microbiological outcomes and they are only validated in narrow groups of patients. Thus, their widespread application could not be encouraged for all patients before performing adequately powered, prospective randomized studies.

Drug-induced acute kidney injury in neonates

PURPOSE OF REVIEW

Acute kidney injury (AKI) is an independent risk factor for morbidity and mortality in critically ill neonates. Nephrotoxic medication exposure is common in neonates. Nephrotoxicity represents the most potentially avoidable cause of AKI in this population.

RECENT FINDINGS

Recent studies in critically ill children revealed the importance of recognizing AKI and potentially modifiable risk factors for the development of AKI such as nephrotoxic medication exposures. Data from critically ill children who have AKI suggest that survivors are at risk for the development of chronic kidney disease. Premature infants are born with incomplete nephrogenesis and are at risk for chronic kidney disease. The use of nephrotoxic medications in the neonatal intensive care unit is very common; yet the effects of medication nephrotoxicity on the short and long-term outcomes remains highly understudied.

SUMMARY

The neonatal kidney is predisposed to nephrotoxic AKI. Our ability to improve outcomes for this vulnerable group depends on a heightened awareness of this issue. It is important for clinicians to develop methods to minimize and prevent nephrotoxic AKI in neonates through a multidisciplinary approach aiming at earlier recognition and close monitoring of nephrotoxin-induced AKI.

Comparative Incidence of Acute Kidney Injury in Critically Ill Patients Receiving Vancomycin with Concomitant Piperacillin-Tazobactam or Cefepime: A Retrospective Cohort Study

STUDY OBJECTIVE

The combination of vancomycin and piperacillin-tazobactam has been associated with an increased risk of acute kidney injury (AKI) in non-critically ill patient populations, but it is still unknown if this association exists in critically ill patients. The objective of this study was to compare the incidence of AKI development during therapy or within 72 hours after completion of therapy in adult critically ill patients who received vancomycin with concomitant piperacillin-tazobactam or cefepime.

DESIGN

Retrospective cohort study.

SETTING

Medical, surgical, and neuroscience intensive care units (ICUs) within a single tertiary care hospital.

PATIENTS

A total of 122 critically ill patients who received at least 48 hours of combination therapy with vancomycin and piperacillin-tazobactam (49 patients) or vancomycin and cefepime (73 patients) during an ICU admission between September 2012 and December 2014.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was AKI development, as determined by the Acute Kidney Injury Network criteria, during combination therapy or within 72 hours of completion of combination therapy. The inverse probability of the treatment-weighting (IPTW) approach was used to account for potential treatment selection bias. AKI incidence was assessed in the unadjusted and propensity score-weighted cohorts. Of the 122 patients, 37 patients (30.3%) developed AKI. In the unadjusted analysis, the incidence of AKI was similar in the piperacillin-tazobactam group compared with the cefepime group (32.7% vs 28.8%, p=0.647). The average treatment effect between the groups was not significant, showing no association between β-lactam choice and AKI (β = -0.004, p=0.958). Secondary outcomes were ICU length of stay, hospital length of stay, AKI duration, and need for renal replacement therapy. The choice of β-lactam was not a significant predictor of any of these outcomes: ICU length of stay (β = 0.436, p=0.780), hospital length of stay (β = 3.819, p=0.125), AKI duration (β = -4.027, p=0.283), and need for renal replacement therapy (β = 2.828, p=0.161).

CONCLUSION

After adjusting for propensity to receive each of the treatment choices, no significant difference was found in the incidence of AKI development or other outcomes between the groups. The previously described finding that concomitant vancomycin and piperacillin-tazobactam increases AKI in non-critically ill patients may not be generalizable to the critically ill population. Prospective evaluation of this hypothesis is warranted.

Clinical Utility and Safety of a Model-Based Patient-Tailored Dose of Vancomycin in Neonates

Pharmacokinetic modeling has often been applied to evaluate vancomycin pharmacokinetics in neonates. However, clinical application of the model-based personalized vancomycin therapy is still limited. The objective of the present study was to evaluate the clinical utility and safety of a model-based patient-tailored dose of vancomycin in neonates. A model-based vancomycin dosing calculator, developed from a population pharmacokinetic study, has been integrated into the routine clinical care in 3 neonatal intensive care units (Robert Debré, Cochin Port Royal, and Clocheville hospitals) between 2012 and 2014. The target attainment rate, defined as the percentage of patients with a first therapeutic drug monitoring serum vancomycin concentration achieving the target window of 15 to 25 mg/liter, was selected as an endpoint for evaluating the clinical utility. The safety evaluation was focused on nephrotoxicity. The clinical application of the model-based patient-tailored dose of vancomycin has been demonstrated in 190 neonates. The mean (standard deviation) gestational and postnatal ages of the study population were 31.1 (4.9) weeks and 16.7 (21.7) days, respectively. The target attainment rate increased from 41% to 72% without any case of vancomycin-related nephrotoxicity. This proof-of-concept study provides evidence for integrating model-based antimicrobial therapy in neonatal routine care.

Management of Acute Kidney Injury and Acid-Base Balance in the Septic Patient

Acute kidney injury (AKI) is an abrupt decrease in kidney function that takes place over hours to days. Sepsis is the leading cause of AKI and portends a particularly high morbidity and mortality, although the severity may vary from a transient rise in serum creatinine to end-stage renal disease. With regard to acid-base management in septic AKI, caution should be used with hyperchloremic crystalloid solutions, and dialysis is often used in the setting of severe acidosis. In the future, biomarkers may help clinicians identify AKI earlier and allow for potential interventions before the development of severe AKI.

Characterization of urinary metabolites as biomarkers of colistin-induced nephrotoxicity in rats by a liquid chromatography/mass spectrometry-based metabolomics approach

Colistin is a polypeptide antibiotic that effectively treats infections caused by multidrug-resistant Gram-negative bacteria, but its clinical use is limited due to nephrotoxicity. The purpose of the present study was to identify biomarkers of colistin-induced nephrotoxicity and to further characterize the mechanisms underlying this process by analyzing urinary metabolites using untargeted metabolomic approach. Rats receiving intraperitoneal administration of colistin sodium methanesulfonate (CMS) (25 or 50mg/kg) exhibited histopathological changes in the kidney and increased blood urea nitrogen levels. Additionally, the levels of phenylalanine, tryptophan, and tyrosine in the urine of the CMS-treated group were significantly higher than those of the control group, suggesting that colistin caused proximal tubular damage. Urinary acetylcarnitine and butyrylcarnitine levels also increased after CMS treatment, but the levels of purine metabolites and metabolites related to the tricarboxylic acid cycle were reduced. The most significant increase in the CMS-treated groups was observed in creatine levels. CMS-induced selective nephrotoxicity may be attributed to relatively high tissue concentrations of colistin in the kidney. Taken together, our results indicate that high levels of colistin in the kidney caused perturbations in the tricarboxylic acid cycle, amino acid metabolism, creatine metabolism, and purine metabolism and ultimately led to kidney injury.

Vancomycin Therapeutic Targets and Nephrotoxicity in Critically Ill Children With Cancer

To obtain pharmacokinetic and pharmacodynamic data for vancomycin in a cohort of critically ill pediatric oncology patients, we analyzed 256 measurements of vancomycin concentrations in 94 patients. Variables were tested as possible risk factors for vancomycin-related nephrotoxicity or death for 28 days. We found the following: mean vancomycin trough serum concentration, 15.6 ± 12.4 μg/mL; mean vancomycin clearance, 0.16 ± 0.098 L/h/kg; and mean vancomycin distribution volume, 1.04 ± 0.11 L/kg. Only 13.6% of serum trough level measurements were between 15 and 20 μg/mL. The trough levels showed a strong correlation with the AUC (area under the curve of serum concentrations vs. time over 24 h to the minimum inhibitory concentration ratio), with a 94% positive predictive value for AUC/MIC ≥ 400, but only for MIC=1. The doses that are currently used (60 mg/kg/d) attained the therapeutic target (AUC/MIC ≥ 400) in only 56% of measurements, considering MIC=1. A serum trough level of ≥ 20 μg/mL was an independent risk for nephrotoxicity (P = 0.0008; odds ratio = 17.83). Vancomycin-related nephrotoxicity was a predictor of death for up to 28 days (P = 0.003, odds ratio = 7.68). Currently administered doses of vancomycin do not reach the therapeutic target for critical cancer patients, particularly if staphylococci isolates have a MIC>1.

Safety profiles of old and new antimicrobials for the treatment of MRSA infections

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of severe nosocomial and community-acquired infections. Various adverse effects have been associated with compounds that are commonly used in the treatment of MRSA.

AREAS COVERED

Prolonged use of high-dose vancomycin has been linked with nephrotoxicity. Linezolid use has been associated with lactic acidosis in regimens longer than 14 days and occurrence of thrombocytopenia in patients with renal impairment. Daptomycin use correlates with reversible and often asymptomatic myopathy. Among new compounds, telavancin has shown increased toxicity compared to vancomycin, especially in patients with severe renal impairment, while a low rate of adverse effects was reported others glycolipopeptides such as dalbavancin and oritavancin and for new cephalosporins. Recently studied oxazolidinones (tedizolid and radezolid) also showed mild adverse effects in Phase 2 and 3 clinical trials.

EXPERT OPINION

Due to the constant increase in antimicrobial resistance, the use of higher doses and prolonged regimens of antibiotics employed in the treatment of Gram-positive infections has become more common and linked to increased toxicity. Furthermore, new compounds with MRSA activity have been recently approved and will be regularly employed in clinical practice. The knowledge of the adverse effects and risk factors for the development of toxicity associated with anti-MRSA antimicrobials is paramount for the correct use of old and new compounds, especially in the treatment of severe infections.

Identification of Risk Factors for Initial Elevated Vancomyin Trough Concentrations

Background: Recent literature suggests that elevated vancomycin trough concentrations (>20 µg/mL) may be associated with an increased risk of nephrotoxicity and lead to an increase in mortality and hospital length of stay. Objective: The purpose of this study was to identify variables that may be predictive of elevated initial vancomycin trough concentrations. Methods: Retrospective case–control study of all adult patients who had an initial vancomycin trough concentration measured between January 1, 2013, and December 31, 2014. Case patients had an initial trough concentration >20 µg/mL, while control patients had an initial trough concentration of ≤20 µg/mL. Patients were excluded from the study if they were in the intensive care unit, had unstable renal function, or if they had cystic fibrosis, solid organ transplant, or bone marrow transplant. Results: Of the 512 vancomycin trough concentrations reviewed, 54 patients met the case definition, while 140 patients were randomly selected as controls. In a multivariate model, baseline serum creatinine, body mass index, heart failure, and malignancy were all independently predictive of an initial vancomycin concentration >20 µg/mL. Conclusions: Reduced baseline renal function coupled with increasing body mass index is associated with an increased risk of an elevated initial vancomycin trough concentration. This risk is further enhanced by the presence of heart failure and/or malignancy. When these risk factors are present, it may be prudent to consider implementation of individualized dosing to achieve initial target concentrations.

Impact of an Antimicrobial Stewardship Program on Patient Safety in Veterans Prescribed Vancomycin

PURPOSE

This study aimed to determine the safety impact of an antimicrobial stewardship program (ASP) on vancomycin-associated nephrotoxicity and to examine risk factors contributing to the development of toxicity.

METHODS

This was a retrospective chart review of data from 453 veterans receiving vancomycin in the VA Western New York Healthcare System between October 2006 and July 2014. Nephrotoxicity was defined as an increase in serum creatinine of ≥ 0.5 mg/dL or by 50% of baseline for 2 consecutive days.

FINDINGS

Patients receiving vancomycin after the implementation of the ASP were less likely to develop nephrotoxicity (odds ratio [OR] = 2.06; 95% CI, 1.02-4.28). Nephrotoxicity occurred in 6.84% of patients from the pre-ASP cohort and in 3.75% of patients after the implementation of the ASP. Predictors of nephrotoxicity included hospital service (surgical service, OR = 2.29; 95% CI, 1.13-4.64), elevated maximum trough concentration (unit OR = 1.15; 95% CI, 1.10-1.20), and concurrent piperacillin/tazobactam therapy (OR = 3.21; 95% CI, 1.43-7.96). The number of vancomycin trough concentration measurements per patient did not vary between the pre-ASP and ASP groups.

IMPLICATIONS

ASPs represent an important aspect of a patient-safety initiative in order to reduce vancomycin-associated nephrotoxicity. Concurrent piperacillin/tazobactam therapy, surgical service, and elevated maximum trough concentration were risk factors for nephrotoxicity.

A SILAC-Based Approach Elicits the Proteomic Responses to Vancomycin-Associated Nephrotoxicity in Human Proximal Tubule Epithelial HK-2 Cells

Vancomycin, a widely used antibiotic, often induces nephrotoxicity, however, the molecular targets and underlying mechanisms of this side effect remain unclear. The present study aimed to examine molecular interactome and analyze the signaling pathways related to the vancomycin-induced nephrotoxicity in human proximal tubule epithelial HK-2 cells using the stable isotope labeling by amino acids in cell culture (SILAC) approach. The quantitative proteomic study revealed that there were at least 492 proteins interacting with vancomycin and there were 290 signaling pathways and cellular functions potentially regulated by vancomycin in HK-2 cells. These proteins and pathways played a critical role in the regulation of cell cycle, apoptosis, autophagy, EMT, and ROS generation. These findings suggest that vancomycin-induced proteomic responses in HK-2 cells involvefunctional proteins and pathways that regulate cell cycle, apoptosis, autophagy, and redox homeostasis. This is the first systemic study revealed the networks of signaling pathways and proteomic responses to vancomycin treatment in HK-2 cells, and the data may be used to discriminate the molecular and clinical subtypes and to identify new targets and biomarkers for vancomycin-induced nephrotoxic effect. Further studies are warranted to explore the potential of quantitative proteomic analysis in the identification of new targets and biomarkers for drug-induced renal toxicity.

Continuous versus intermittent infusion of vancomycin in adult patients: A systematic review and meta-analysis

Continuous infusion of vancomycin (CIV) and intermittent infusion of vancomycin (IIV) are two major administration strategies in clinical settings. However, previous articles comparing the efficacy and safety of CIV versus IIV showed inconsistent results. Therefore, a meta-analysis was conducted to compare the efficacy and safety of CIV and IIV. PubMed, the Cochrane Library and Web of Science up to June 2015 were searched using the keywords 'vancomycin', 'intravenous', 'parenteral', 'continuous', 'intermittent', 'discontinuous', 'infusion', 'administration' and 'dosing'. Eleven studies were included in the meta-analysis. Neither heterogeneity nor publication bias were observed. Patients treated with CIV had a significantly lower incidence of nephrotoxicity compared with patients receiving IIV [risk ratio (RR)=0.61, 95% confidence interval (CI) 0.47-0.80; P<0.001]. No significant difference in treatment failure between the two groups was detected. Mortality between patients receiving CIV and patients receiving IIV was similar (RR=1.15, 95% CI 0.85-1.54; P=0.365). This meta-analysis showed that CIV had superior safety compared with IIV, whilst the clinical efficacy was not significantly different. A further multicentre, randomised controlled trial is required to confirm these results.

Safety and Outcome of Pharmacy-Led Vancomycin Dosing and Monitoring

Background: Therapeutic vancomycin trough levels correlate with therapeutic success and the development of renal failure. In this study, we aimed to describe the safety and outcome of pharmacy-led vancomycin dosing and monitoring. Methods: We included adults requiring vancomycin for >48 h and who had a vancomycin trough level drawn near steady state. The primary outcome of the comparison was the achievement of therapeutic trough levels, defined as 10-20 µg/ml. Secondary outcome included acute renal failure. We compared these outcomes before and after the implementation of pharmacy-led vancomycin dosing and monitoring. Result: During the study period, a total of 278 patients were in the preimplementation phase and 286 were in the postintervention phase. There was a clear increase in the percentage of patients achieving the therapeutic range (50.5 vs. 79.7%, p = 0.0001) and an increase in the percentage of levels within the therapeutic range (31.6 vs. 59.1%; p = 0.0001). The number of cases receiving vancomycin increased by 5% and the duration of therapy decreased by 19.5%. More patients attained a therapeutic range of 10-20 µg/ml (i.e. the level was 31.6% in the preintervention and 59.1% in the postintervention phase). Conclusions: A higher percentage of patients achieved a therapeutic range and less nephrotoxicity when using a pharmacy-led protocol for vancomycin dosing.

Top Guns: The "Maverick" and "Goose" of Empiric Therapy

BACKGROUND

Vancomycin and piperacillin-tazobactam are commonly used first guns in the empiric management of critically ill patients. Current studies suggest an increased prevalence of acute kidney injury with concomitant use, however, these studies are few and limited by small sample size. The purpose of this study was to compare the prevalence of nephrotoxicity after treatment with vancomycin alone and concomitant vancomycin and piperacillin-tazobactam treatment at our institution.

HYPOTHESIS

Concomitant vancomycin and piperacillin-tazobactam-treated patients will experience greater prevalence of nephrotoxicity compared with vancomycin-only treated patients.

METHODS

This was a retrospective cohort of patients treated with vancomycin for gram-positive or mixed infections in our facility from 2005 to 2009 who were not receiving hemodialysis at the time of admission. Included patients were stratified by treatment with vancomycin, vancomycin/piperacillin-tazobactam, or vancomycin/an alternative gram-negative rod (GNR) antibiotic. p values for categorical variables were computed using χ(2) while continuous variables were computed using Kruskal-Wallis. Variables deemed statistically significant (< 0.05) were included in the multivariable, log-binomial regression model. Relative risk (RR) and 95% confidence intervals (CI), and p values were computed using a generalized estimating equation (GEE) approach with robust standard errors (i.e., Huber White "sandwich variance" estimates) to accommodate a correlated data structure corresponding to multiple episodes of infection per individual.

RESULTS

A total of 530 patients with 1,007 episodes of infection, were treated with vancomycin (150 patients/302 episodes of infection), vancomycin/piperacillin-tazobactam (213 patients/372 episodes of infection), or vancomycin/GNR alternative (167 patients/333 episodes of infection). Patient demographics, comorbidities, sites of infection, and organisms of infection were compared among groups. After adjusting for statistically significant variables, neither vancomycin/piperacillin-tazobactam (RR = 1.1, 95% CI = 0.99-1.2; p = 0.073) nor vancomycin/GNR alternative (RR = 1.1, 95% CI = 0.98-1.2; p = 0.097) were found to be associated with an increased risk for nephrotoxicity compared with vancomycin alone.

CONCLUSION

A difference in nephrotoxicity was not observed between vancomycin and vancomycin/piperacillin-tazobactam-treated patients at our institution. Concomitant use as empiric therapy is appropriate, although larger sample sizes are needed to analyze closely this relation among at-risk subsets of this population.

Risk factors for kidney injury during vancomycin and piperacillin/tazobactam administration, including increased odds of injury with combination therapy

Background

Acute kidney injury (AKI) occurs frequently in hospitalized patients and has been associated with the administration of certain medications. Concerns have been raised in recent reports that the antibiotic combination of vancomycin and piperacillin/tazobactam (combV/P) may be more associated with AKI than monotherapy with either drug.

Methods

To compare the incidence of and risk factors for AKI in patients receiving combV/P versus monotherapy with either drug, a retrospective study was conducted in non-critically ill inpatients at a large urban teaching hospital. AKI was defined as either: (1) Increase in serum creatinine ≥0.5 mg/dl OR (2) ≥1.5-fold creatinine increase from admission baseline. In addition to standard multivariable regression adjustment, propensity score weighting was used as a robust approach to reduce the effects of covariate confounding when estimating the adjusted odds of AKI.

Results

A total of 228 patients were evaluated. The overall incidence of AKI was 11.8 % (27 of 228 patients). AKI occurred in 4 of 101 patients in the vanc group (4.0 %), 4 of 26 patients in the piptazo group (15.4 %), and 19 of 101 patients in the combV/P group (18.8 %). The univariable odds of AKI was significantly lower in the vanc group compared to both the combV/P group (OR 0.178, 95 % CI 0.058–0.544, p = 0.003) and piptazo (OR 0.227, 95 % CI 0.053–0.978, p = 0.047) group. A multivariable model accounting for baseline characteristics again showed that vanc monotherapy was associated with lower odds of AKI than combV/P (OR 0.14, 95 % CI 0.04–0.52, p = 0.004). Male sex was also associated with lower odds of AKI (OR 0.28, 95 % CI 0.10–0.79, p = 0.02) in the multivariable model. In the propensity score analysis using inverse probability of treatment weighting (IPTW), vanc monotherapy and male sex were again associated with lower odds of AKI (OR 0.17; 95 % CI 0.04–0.62, p = 0.008 and OR 0.28, 95 % CI 0.09–0.89, p = 0.03, respectively).

Conclusion

This study substantiates recent reports that combV/P may be more associated with AKI than vanc monotherapy in hospital inpatients. AKI also appears to be more likely in females during therapy with these antimicrobials. While severity of illness is difficult to account for, these findings are further justification for narrowing antibiotic coverage when possible after this combination has been initiated in hospitalized patients.

Hospital Admission following Acute Kidney Injury in Kidney Transplant Recipients Is Associated with a Negative Impact on Graft Function after 1-Year

The incidence and outcomes of acute kidney injury (AKI) in kidney transplantation are poorly known. Retrospective cohort analysis was performed on the data of all patients (≥3 months after transplantation and ≥16 years of age) admitted to the hospital due to medical or surgical complications from 2007 to 2010. We analyzed 458 kidney transplant recipients, 55.2% men, median age 49 (IQR, 36-58) years, median of 12.5 (IQR, 3-35) months after kidney transplantation; admitted to the hospital due to medical or surgical complications. Most of the patients received a kidney from a deceased donor (62.2%), the primary cause for hospital admission was infection (60.7%) and 57 (12.4%) individuals were diagnosed with acute rejection (AR). The incidence of AKI was 82.3%: 31.9% stage 1, 29.3% stage 2 and 21.2% stage 3. Intensive care unit (ICU) admission (OR 8.90, 95% CI: 1.77-44.56 p = 0.008), infection (OR 5.73, 95% CI: 2.61-12.56, p<0.001) and the use of contrast media (OR 9.34, 95% CI: 2.04-42.70, p = 0.004) were the independent risk factors for AKI development. The mortality rate was 2.1% and all patients who died were diagnosed with AKI. Even after the exclusion of AR cases, at the end of 12 months, the individuals with AKI exhibited higher percent changes in creatinine values when compared with individuals without AKI (9.1% vs. -4.3%; p<0.001). According to KDIGO system, we found a high incidence of AKI among the complications of renal transplantation. As in other scenarios, AKI was associated with renal function loss at 1-year after the hospital discharge.

Vancomycin-Associated Nephrotoxicity: The Obesity Factor

BACKGROUND

Current recommendations suggest that vancomycin dosing utilize actual rather than ideal body weight in obese patients. Thus, obese patients may be at greater risk for nephrotoxicity. The purpose of this study was to compare the incidence of nephrotoxicity in vancomycin-treated obese and lean patients at our institution, where unadjusted, actual body weight-based dosing (capped at 2 g per dose twice daily) is used. We expected obese patients to experience a greater incidence of nephrotoxicity than lean patients.

METHODS

This study examined a retrospective cohort of patients treated with vancomycin for gram-positive or mixed infections in our facility from 2005-2009 who were not receiving hemodialysis at the time of admission. Patients were stratified by body mass index (BMI; obese ≥30 kg/m(2) vs. lean <30 kg/m(2)). Relative risk (RR), 95% confidence intervals (CIs), and p values were computed using a generalized estimating equation to accommodate a correlated data structure corresponding to multiple episodes of infection per individual. Multivariable analysis was performed.

RESULTS

A total of 530 patients (207 obese; 323 lean) with 1,007 episodes of infection were treated with vancomycin. Patient demographics, co-morbidities, sites of infection, and infecting organisms were similar in the two groups. Female gender (p=0.042), diabetes mellitus (DM) (p=0.018), and hypertension (HTN) (p=0.0009) were more often associated with obesity, whereas allografts (p=0.022) and peripheral vascular disease (p=0.036) were more often present in lean patients. The Acute Physiology and Chronic Health Evaluation II score >21 was the only variable associated with nephrotoxicity (p=0.039). After adjusting for statistically significant variables, obesity was found not to be associated with a greater risk of nephrotoxicity (RR=0.98; 95% CI=0.93-1.04; p=0.59).

CONCLUSION

No difference in nephrotoxicity was observed between lean and obese patients treated with vancomycin at our institution.

Enhanced oral bioavailability of vancomycin in rats treated with long-term parenteral nutrition

Long-term parenteral nutrition (PN) can induce intestinal atrophy, leading to a loss of epithelial integrity in the small intestines. This change may alter the intestinal permeability of vancomycin (VCM), a non-absorbable antibiotic. The aim of the present study was to investigate the effect of PN on the pharmacokinetics of VCM in rats. VCM was intravenously (5 mg/kg) or intraduodenally (20 mg/kg) administered to control and PN rats, which were prepared by administration of PN for 9 days. After intravenous administration, there were no significant differences in any of the VCM pharmacokinetic parameters between the control and PN rats. However, after intraduodenal administration, the maximum concentration and area under the plasma concentration-time curve of VCM in PN rats was approximately 2.4- and 2.6-fold higher, respectively, than in the control rats; the calculated bioavailability was approximately 0.5 and 1.3 % in control and PN rats, respectively. These results indicated that PN administration did not affect VCM disposition, but enhanced VCM absorption; however, the enhanced oral VCM bioavailability was statistically, not clinically, significant. Therefore, while long-term PN administration may play a role in the enhancement of VCM bioavailability, this effect may be negligible without any complications.

How to use vancomycin optimally in neonates: remaining questions

In neonates, vancomycin, a narrow-spectrum antibiotic, is the first choice of treatment of late-onset sepsis predominantly caused by Gram-positive bacteria (coagulase-negative staphylococci and enterococci). Although it has been used for >50 years, prescribing the right dose and dosing regimen remains a challenge in neonatal intensive care units for many reasons including high pharmacokinetic variability, increase in the minimal inhibition concentration against staphylococci, lack of consensus on dosing regimen and way of administration (continuous or intermittent), duration of treatment, use of therapeutic drug monitoring, limited data on short- and long-term toxicity, risk of mutant selection and errors of administration linked to concentrated formulations. This article highlights and discusses future research directions, with specific attention given to dosing optimization of vancomycin, including the advantages of modeling and simulation approaches.

Glycopeptide antibiotics: evolving resistance, pharmacology and adverse event profile

The first glycopeptide antibiotic was vancomycin, isolated from the soil in the 1950s; since then, the class has expanded to include teicoplanin and the new semisynthetic glycopeptides dalbavancin, oritavancin and telavancin. They are bactericidal, active against most Gram-positive organisms, and in a concentration-dependent manner, inhibit cell wall synthesis. Resistance to vancomycin has emerged, especially among enterococci and Staphylococcus aureus through a variety of mechanisms. This emerging resistance to vancomycin makes proper dosing and monitoring of the area under the curve/MIC critically important. The chief adverse effect of vancomycin is nephrotoxicity, which is also intricately related to its dose. The efficacy of the semisynthetic glycopeptides has been demonstrated in skin and soft-tissue infections, but remains to be seen in serious methicillin-resistant Staphylococcus aureus infections.

Addition of Vancomycin to Cefazolin Prophylaxis Is Associated With Acute Kidney Injury After Primary Joint Arthroplasty

BACKGROUND

With increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in patients undergoing hip and knee arthroplasty, some have advocated a dual-antibiotic regimen including vancomycin as prophylaxis against surgical site infections. However, routine administration of vancomycin may result in impaired renal functions in susceptible patients.

QUESTIONS/PURPOSES

The purpose of this study was to determine whether patients receiving antibiotic prophylaxis with cefazolin and vancomycin have a higher risk of postoperative acute kidney injury (AKI) compared with patients receiving cefazolin alone before elective primary hip and knee arthroplasty. We also aimed to compare severity and recovery of AKI in these two cohorts and to determine independent risk factors for AKI.

METHODS

We retrospectively evaluated a series of 1828 patients undergoing primary hip and knee arthroplasty over a 2-year period who received either cefazolin (n = 500) or cefazolin and vancomycin (n = 1328) as perioperative antibiotic prophylaxis. During the study period, a perceived high prevalence of MRSA infections at our institution led some surgeons to add vancomycin to the prophylactic antibiotic regimen. The patient characteristics, case mix, and preoperative renal function and baseline creatinine clearance were similar between the two groups. We defined AKI according to the published Acute Kidney Injury Network (AKIN) criteria, and the risk of AKI in both groups was compared. We also compared the proportions of patients by AKIN severity stage and assessed recovery as defined by creatinine levels showing kidney function reaching 50% baseline. The American Society of Anesthesiologists (ASA) classification, preoperative chronic kidney disease, intraoperative fluid requirements, and estimated blood loss were recorded. We analyzed the data using a multivariate logistic regression model to identify potential independent risk factors, including dual antibiotic therapy.

RESULTS

Patients receiving dual antibiotics were more likely to develop AKI compared with those receiving cefazolin alone (13% versus 8%, p = 0.002). Dual-antibiotic prophylaxis also was associated with greater severity; patients in the dual antibiotic group had higher rates of Grade II and III acute kidney injury (3% versus 0%, p = 0.003). There was no difference in the rate of return to baseline renal function (2 ± 1.4 days versus 3 ± 3.4 days; mean difference, 0.5 days; 95% confidence interval [CI], -0.2 to 1.2 days; p = 0.155). Controlling for confounding variables, dual antibiotic prophylaxis (adjusted odds ratio [OR], 1.82; 95% CI, 1.25-2.64; p = 0.002), ASA class (adjusted OR, 1.64; 95% CI, 1.24-2.17; p = 0.001), and preoperative kidney disease (adjusted OR, 1.81; 95% CI, 1.30-2.52; p = 0.001) were independent risk factors for AKI after primary total joint arthroplasty.

CONCLUSIONS

Without a clear advantage in reducing surgical site infections, the utility and safety of routine addition of vancomycin to the prophylactic regimen in all patients undergoing primary hip and knee arthroplasty should be avoided. Further prospective studies should look at the efficacy of preoperative MRSA screening, decolonization, and selective use of vancomycin in high-risk patients.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Intravenous Antibiotics Used in the Treatment of Methicillin-Resistant Staphylococcus Aureus

Methicillin-resistant Staphylococcus aureus (MRSA) continues to cause significant morbidity and mortality. Despite advances in medical care, the prevalence of both community-acquired and hospital-acquired MRSA has progressively increased. Community-acquired MRSA typically occurs in patients without recent illness or hospitalization, presents as acute skin and soft tissue infections, and is usually not multidrug resistant. Hospital-acquired MRSA, however, presents in patients recently hospitalized or treated in long-term care settings and in those who have had medical procedures and is usually associated with multidrug-resistant strains. Both types of infections, if not properly treated, have the potential to become invasive. This article discusses current intravenous antibiotics that are available for the empiric treatment of MRSA infections along with a newer phenomenon known as the "seesaw effect."

Intravenous Antibiotics Used in the Treatment of Methicillin-Resistant Staphylococcus Aureus

Methicillin-resistant Staphylococcus aureus (MRSA) continues to cause significant morbidity and mortality. Despite advances in medical care, the prevalence of both community-acquired and hospital-acquired MRSA has progressively increased. Community-acquired MRSA typically occurs in patients without recent illness or hospitalization, presents as acute skin and soft tissue infections, and is usually not multidrug resistant. Hospital-acquired MRSA, however, presents in patients recently hospitalized or treated in long-term care settings and in those who have had medical procedures and is usually associated with multidrug-resistant strains. Both types of infections, if not properly treated, have the potential to become invasive. This article discusses current intravenous antibiotics that are available for the empiric treatment of MRSA infections along with a newer phenomenon known as the “seesaw effect.”

The association of patient complexities with antibiotic ordering

BACKGROUND

Antibiotic treatment decisions for medically complex patients are complicated, as the risk of undertreatment may be severe, whereas overtreatment may be associated with adverse effects and the emergence of antibiotic resistant pathogens.

OBJECTIVE

To determine the influence of patient complexities on providers' decisions to prescribe antibiotics in 3 common hospital-based clinical vignettes.

DESIGN

A physician survey.

SETTING

Three urban medical centers in Los Angeles County, California.

PARTICIPANTS

Hospital-based physicians.

MEASUREMENTS

Physicians were presented 3 clinical vignettes, with variations by patient age, comorbidity burden, functional status, and follow-up, and asked to choose the best antibiotic regimen. We described the association of additional patient complexity on the proportion of guideline-adherent antibiotic choices.

RESULTS

In the survey, 28% to 49% of physicians recommended antibiotics that were inconsistent with national guidelines. This percentage increased to 48% to 63% for medically complex patients, defined as those with either older age, high medical comorbidity burden, poor functional status, or limited follow-up after hospital discharge (P < 0.01).

CONCLUSIONS

In 3 vignettes depicting common clinical scenarios among hospitalized adults, inappropriate antibiotic use was prevalent and occurred more often for patients with medical complexities. Treatment guidelines should consider addressing medically complex patients in the context of infection management.

Endothelial, renal and hepatic variables in Wistar rats treated with Vancomycin

Vancomycin (VCM) is indicated in combat against Gram-positive infections, but it is not considered a first-choice drug because of its adverse effects. It is believed that oxidative stress is the primary mechanism of endothelial injury and the consequent VCM toxicity, which varies from phlebitis to nephrotoxicity. Moreover, dose recommendations, dilution, rates and types of infusion are still controversial. The aim of this study was to determine the effect of different VCM dilutions in endothelial, liver and kidney injuries by biochemical parameters and histopathological analysis. Wistar rats were randomly divided into six groups and subjected to femoral vein cannulation for drug administration. Control groups received 0.9 ml of saline and the others received VCM (10mg/Kg/day) at dilutions of 5.0 and 10.0 mg/mL for 3 and 7 days. Homocysteine, hs-CRP, AST, ALT, GGT, urea, creatinine, lycopene, alpha-tocopherol, beta-carotene and retinol were analyzed. Kidney, liver and cannulated femoral vein fragments were collected.This study showed alterations in ALT which featured hepatotoxicity. However, drug dilutions were not able to show changes in other biochemical parameters. In contrast, kidney and endothelium pathological changes were observed. More studies are needed to characterize VCM induced kidney and endothelium toxicity and biochemical markers able to show such morphological modifications.

Can Nasal Methicillin-Resistant Staphylococcus aureus Screening Be Used to Avoid Empiric Vancomycin Use in Intra-Abdominal Infection?

BACKGROUND

Vancomycin is used widely as empiric therapy for gram-positive organisms in patients with an intra-abdominal infection (IAI), even in those with no history of methicillin-resistant Staphylococcus aureus (MRSA) infection or colonization. Potential adverse effects of vancomycin include nephrotoxicity, increased cost, and bacterial resistance. We hypothesized that MRSA nasal screening could be used to predict patients with a MRSA IAI and used to avoid unnecessary empiric vancomycin use.

METHODS

A surgical infections database collected prospectively from a single institution was reviewed for all IAIs between January 1, 2000-December 31, 2011. Patients with and without MRSA obtained from abdominal cultures as either a monomicrobial or polymicrobial isolate were compared by univariate analysis. A multivariable logistic regression was performed to identify independent predictors of MRSA IAI.

RESULTS

Of 2,591 patients with an IAI, 240 patients had a nasal MRSA screen within 30 d prior to infection and abdominal culture data, with an incidence of 23% for MRSA IAI. Patients with MRSA IAI (n=45) had more healthcare associated infections, lower white blood cell counts and greater rates of positive nasal MRSA screenings compared with those with non-MRSA IAI. By multivariable analysis (C statistic=0.908), the strongest independent predictor of an MRSA IAI was a positive MRSA screen (odds ratio [OR] 40.9, confidence interval [CI] 14.2-118.1). The positive predictive value for a MRSA screen was 53% whereas the negative predictive value of a MRSA screen was 97%.

CONCLUSION

A negative MRSA nasal screen indicates with near certainty the absence of MRSA as part of an IAI. In the setting of a recent screen, empiric vancomycin can be withheld. Further, rapid MRSA nasal screening could be used to forego or to discontinue vancomycin therapy rapidly in the setting of IAI. This change in empiric antibiotic management of IAI may lead to decreased morbidity, reduction in cost, and a decrease in bacterial resistance.

Genome-Wide Association Study of Serum Creatinine Levels during Vancomycin Therapy

Vancomycin, a commonly used antibiotic, can be nephrotoxic. Known risk factors such as age, creatinine clearance, vancomycin dose / dosing interval, and concurrent nephrotoxic medications fail to accurately predict nephrotoxicity. To identify potential genomic risk factors, we performed a genome-wide association study (GWAS) of serum creatinine levels while on vancomycin in 489 European American individuals and validated findings in three independent cohorts totaling 439 European American individuals. In primary analyses, the chromosome 6q22.31 locus was associated with increased serum creatinine levels while on vancomycin therapy (most significant variant rs2789047, risk allele A, β = -0.06, p = 1.1 x 10^-7). SNPs in this region had consistent directions of effect in the validation cohorts, with a meta-p of 1.1 x 10^-7. Variation in this region on chromosome 6, which includes the genes TBC1D32/C6orf170 and GJA1 (encoding connexin43), may modulate risk of vancomycin-induced kidney injury.

Trough concentration over 12.1 mg/L is a major risk factor of vancomycin-related nephrotoxicity in patients with therapeutic drug monitoring

BACKGROUND

High doses of vancomycin increase the risk of nephrotoxicity, but the quantitative relationship between vancomycin exposure and nephrotoxicity is still controversial. This study evaluated the relationship between vancomycin trough concentration and nephrotoxicity, and risk factors for nephrotoxicity in patients undergoing therapeutic drug monitoring.

METHODS

A total of 1269 cases from patients who underwent therapeutic drug monitoring were collected from 2006 to 2010. Receiver operating characteristic curve analysis was used to evaluate the relationship between trough concentration and the incidence of nephrotoxicity. Logistic regression using the generalized Least Absolute Shrinkage and Selection Operator (lasso) method was used to evaluate possible risk factors for nephrotoxicity. The data were divided into high/low-concentration groups by the cutoff value obtained from the receiver operating characteristic curve, and additional logistic regression using the generalized lasso method was performed for each group.

RESULTS

The cutoff value of the vancomycin trough concentration was 12.1 mg/L. Patients with high concentrations (>12.1 mg/L) were more likely to develop nephrotoxicity (odds ratio = 16.0, 95% confidence interval, 8.2-31.1). The vancomycin trough concentration was the only significant risk factor for nephrotoxicity identified using the generalized lasso (P < 0.001). In contrast, no factor was associated with nephrotoxicity in the low-concentration group.

CONCLUSIONS

Vancomycin trough concentrations over 12.1 mg/L were associated with an increased risk of nephrotoxicity. This is lower than the known threshold. Trough vancomycin concentration over the threshold was the only risk factor of nephrotoxicity among demographic factors, dosing regimen, and other clinical conditions in this study. It is suggested that vancomycin trough concentrations greater than 12.1 mg/L require close monitoring for nephrotoxicity.

Balancing vancomycin efficacy and nephrotoxicity: should we be aiming for trough or AUC/MIC?

Sixty years later, the question that still remains is how to appropriately utilize vancomycin in the pediatric population. The Infectious Diseases Society of America published guidelines in 2011 that provide guidance for dosing and monitoring of vancomycin in adults and pediatrics. However, goal vancomycin trough concentrations of 15-20 μg/mL for invasive infections caused by methicillin-resistant Staphylococcus aureus were based primarily on adult pharmacokinetic and pharmacodynamic data that achieved an area under the curve to minimum inhibitory concentration ratio (AUC/MIC) of ≥400. Recent pediatric literature shows that vancomycin trough concentrations needed to achieve the target AUC/MIC are different than the adult goal troughs cited in the guidelines. This paper addresses several thoughts, including the role of vancomycin AUC/MIC in dosing strategies and safety monitoring, consistency in laboratory reporting, and future directions for calculating AUC/MIC in pediatrics.

Antimicrobial delivery systems for local infection prophylaxis in orthopedic- and trauma surgery

Infectious complications occur in a minor but significant portion of the patients undergoing joint replacement surgery or fracture fixation, particularly those with severe open fractures, those undergoing revision arthroplasty or those at elevated risk because of poor health status. Once established, infections are difficult to eradicate, especially in the case of bacterial biofilm formation on implanted hardware. Local antibiotic carriers offer the prospect of controlled delivery of antibiotics directly in target tissues and implant, without inducing toxicity in non-target organs. Polymeric carriers have been developed to optimize the release and targeting of antibiotics. Passive polymeric carriers release antibiotics by diffusion and/or upon degradation, while active polymeric carriers release their antibiotics upon stimuli provided by bacterial pathogens. Additionally, some polymeric carriers gelate in-situ in response to physiological stimuli to form a depot for antibiotic release. As antibiotic resistance has become a major issue, also other anti-infectives such as silver and antimicrobial peptides have been incorporated in research. Currently, several antibiotic loaded biomaterials for local infection prophylaxis are available for use in the clinic. Here we review their advantages and limitations and provide an overview of new materials emerging that may overcome these limitations.

STUDY OF THE DIFFERENT RELEASE CHARACTERISTICS OF ANTIBIOTICS FROM PATIENTS: A DYNAMIC ELUTING SYSTEM TO INVESTIGATE DRUG RELEASE FROM ANTIBIOTIC-IMPREGNATED CALCIUM SULFATE DELIVERY

Background: Antibiotic-impregnated calcium sulfate delivery systems (ACDS) are commonly used to treat chronic osteomyelitis. Our research is to investigate drug release in vitro over a longer period, as a cautious predictor of in vivo release. Methods: The local release behavior of antibiotic in vitro was simulated. The consecutive dynamic eluting experiment was performed based on the pro-operative characteristic of osteomyelitis patients and the determined results of drug concentration in the human drainage tissue fluid (DTF). The concentration of each drug in the receiving solution was detected by ultra-performance liquid chromatography-tandem quadrupole detector mass spectrometry. The ACDS was reviewed by scanning electronic microscopy (SEM) after 48 h, and prepared to be eluted for another examination after 33 days. The mechanism of antibiotic release was analyzed by using the Ritger–Peppas and Weibull equations. Results: The cumulative release rate of vancomycin in a vancomycin-calcium sulfate delivery system (VCDS) was 77.50 % (3.0 mm diameter) and 72.43 % (4.8 mm diameter), while that of the tobramycin in a tobramycin-calcium sulfate delivery system (TCDS) was 88.0 % (3.0 mm diameter) and 84.55 % (4.8 mm diameter). At the 15th day, approximately 27.92% of vancomycin was and 29.35% of tobramycin was released from the local implant in vivo. Using SEM, numerous vancomycin and tobramycin particles were found to be attached to the columnar calcium sulfate crystals at the start of the experiment. The release behavior of the two antibiotics followed a combination of Fickian diffusion and Case II transport mechanisms within the first 48 h, and a Fickian diffusion mechanism during the subsequent time period. The correlation coefficient of tobramycin and vancomycin in vivo and in vitro was 0.9704–0.9949 and 0.9549–0.9782, respectively. Conclusion: A good correlation of the in vivo and in vitro cumulative release rates was observed by comparing the cumulative release rate of drugs in vitro by means of the dynamic eluting model, and in the DTF. Therefore, our study has proved that it is possible to use the dynamic eluting model as a cautious predictor of in vivo release.

Influence of vancomycin infusion methods on endothelial cell toxicity

Peripheral intravenous therapy is frequently used in routine hospital practice and, due to various factors, its most common side effect is phlebitis. The infusion of vancomycin is particularly associated with phlebitis despite its widespread use. French guidelines recommend central intravenous infusion for high concentrations of vancomycin, but peripheral intravenous therapy is often preferred in intensive care units. Methods of vancomycin infusion are either intermittent infusion or continuous infusion. A comparison of these methods under in vitro conditions simulating clinical use could result in better infusion efficacy. Human umbilical vein endothelial cells (HUVECs) were therefore challenged with clinical doses of vancomycin over a 24- to 72-h period using these infusion methods. Cell death was measured with the alamarBlue test. Concentration-dependent and time-dependent vancomycin toxicity on HUVECs was noted with a 50% lethal dose at 5 mg/ml after 24 h, reaching 2.5 mg/ml after 72 h of infusion, simulating long-term infusion. This toxicity does not seem to be induced by acidic pH. In comparing infusion methods, we observed that continuous infusion induced greater cell toxicity than intermittent infusion at doses higher than 1 g/day. The increasing use of vancomycin means that new guidelines are required to avoid phlebitis. If peripheral intravenous therapy is used to reduce infusion time, along with intermittent infusion, vein irritation and localized phlebitis may be reduced. Further studies have to be carried out to explore the causes of vancomycin endothelial toxicity.

Visualized detection of vancomycin by supramolecular hydrogelations

Here we report on a visualized detection system for vancomycin based on supramolecular hydrogelations.

Conventional- versus high-dose vancomycin regimen in patients with acute bacterial meningitis: a randomized clinical trial

OBJECTIVE

Efficacy of the conventional- versus high-dose vancomycin regimen in patients with acute bacterial meningitis was compared.

METHODS

In a randomized clinical trial 44 patients with acute bacterial meningitis were randomly assigned to the conventional- or high-dose vancomycin groups. Clinical and laboratory parameters were used for evaluation of response to the treatment regimens.

RESULTS

In the high-dose group, leukocytosis and fever resolved significantly faster than those in the conventional group. Furthermore, the length of hospitalization was shorter and Glasgow Coma Scale at the end of 10th day was significantly lower in the high dose compared to the conventional group. Trend of creatinine clearance changes did not differ significantly between the two groups.

CONCLUSION

In comparison to the conventional-dose regimen, the high-dose vancomycin regimen was associated with significantly more favorable clinical response without increase in the incidence of nephrotoxicity in patients with acute bacterial meningitis.

Evidence-based protocol for prophylactic antibiotics in open fractures: improved antibiotic stewardship with no increase in infection rates

BACKGROUND

Evidence-based guidelines for prophylactic antibiotic use in open fractures recommend short-course, narrow-spectrum antibiotics for Gustilo Grade I or II open fractures and broader gram-negative coverage for Grade III open fractures. No studies to date have assessed the impact of these guidelines on infection rates in open fractures. Infection rates before and after the new protocol implementation were examined.

METHODS

A new protocol was implemented including antibiotic prophylaxis based on grade of open fracture: Grade I/II fractures, cefazolin (clindamycin if allergy); Grade III fractures, ceftriaxone (clindamycin and aztreonam if allergy) for 48 hours. Aminoglycosides, vancomycin, and penicillin were removed from the protocol. Data for 174 femur and tibia/fibula open fractures (101 preprotocol and 73 postprotocol) were analyzed. Patients who were moribund or managed at another institution for greater than 24 hours were excluded. The National Healthcare Safety Network risk index was used to provide risk adjustment.

RESULTS

No significant differences in the study cohorts (preprotocol and postprotocol) were identified for demographics (age, 37.2 [14.8] years vs. 40.0 [17.9] years; male, 71.3% vs. 79.5%) or mechanism of injury (motor vehicle crash, 67.3% vs. 64.4%; other blunt, 28.7% vs. 32.9%; penetrating, 4.0% vs. 2.8%). After protocol implementation, the use of aminoglycoside and glycopeptide antibiotics was significantly reduced (53.5% vs. 16.4%, p = 0.0001). The skin and soft tissue infection rate per fracture event was 20.8% before and 24.7% after protocol implementation (p = 0.58). There was no statistically significant change after stratification for fracture grade, National Healthcare Safety Network risk index, or fracture site. The rate per fracture event of resistant gram-positive and gram-negative organisms (15.8% vs. 17.8%, p = 0.84) and methicillin-resistant Staphylococcus aureus (2.0% vs. 4.1%, p = 0.65) was not different.

CONCLUSION

Implementation of an evidence-based protocol for open fracture antibiotic prophylaxis resulted in significantly decreased use of aminoglycoside and glycopeptide antibiotics with no increase in skin and soft tissue infection rates.

LEVEL OF EVIDENCE

Therapeutic study, level IV.