Vancomycin: over 50 years later and still a work in progress

Serum concentration of continuously administered vancomycin influences efficacy and safety in critically ill adults: a systematic review

OBJECTIVES

Vancomycin is used to treat Gram-positive infections in critically ill adults. For vancomycin administered by continuous infusion (CI), various target ranges have been used, ranging from 15-20 mg/L to 30-40 mg/L. This systematic literature review was conducted to investigate the impact of steady-state serum concentration (Css) of CI on safety and efficacy of therapy in critically ill adults.

METHODS

Relevant literature was identified by searching two electronic databases (PubMed, Cochrane Library) and Google Scholar from inception until July 2023, focusing on studies reporting measured Css and treatment outcomes (e.g. mortality, nephrotoxicity) with CI. Due to study heterogeneity, a narrative synthesis of the evidence was performed.

RESULTS

Twenty-one publications were included with a total of 2949 patients. Mortality was higher (two studies, n = 388 patients) and clinical cure was lower (one study, n = 40 patients) with Css < 15 mg/L measured 24 h after initiation of CI (C24). An adequate loading dose appeared most important for maintaining higher C24. Generally, higher Css was associated with higher rates of acute kidney injury (AKI) (15 studies, n = 2331 patients). It was calculated that Css < 25 mg/L (versus ≥25 mg/L) was preferable for reducing nephrotoxicity (three studies, n = 515 patients).

CONCLUSIONS

Despite sparse data availability, the target range of 15-25 mg/L in CI may increase clinical cure and reduce mortality and AKI. In future research, vancomycin Css cohorts should be formed to allow evaluation of the impact of Css of CI on treatment outcomes.

PK-RNN-V E: A deep learning model approach to vancomycin therapeutic drug monitoring using electronic health record data

Vancomycin is a commonly used antimicrobial in hospitals, and therapeutic drug monitoring (TDM) is required to optimize its efficacy and avoid toxicities. Bayesian models are currently recommended to predict the antibiotic levels. These models, however, although using carefully designed lab observations, were often developed in limited patient populations. The increasing availability of electronic health record (EHR) data offers an opportunity to develop TDM models for real-world patient populations. Here, we present a deep learning-based pharmacokinetic prediction model for vancomycin (PK-RNN-V E) using a large EHR dataset of 5,483 patients with 55,336 vancomycin administrations. PK-RNN-V E takes the patient's real-time sparse and irregular observations and offers dynamic predictions. Our results show that RNN-PK-V E offers a root mean squared error (RMSE) of 5.39 and outperforms the traditional Bayesian model (VTDM model) with an RMSE of 6.29. We believe that PK-RNN-V E can provide a pharmacokinetic model for vancomycin and other antimicrobials that require TDM.

Retrospective multicentre matched cohort study comparing safety and efficacy outcomes of intermittent-infusion versus continuous-infusion vancomycin

BACKGROUND

Patients with good renal function receiving intermittent-infusion vancomycin (IIV) may require total daily doses ≥4 g to achieve trough concentrations of 15-20 mg/L, increasing the risk of vancomycin-associated nephrotoxicity. Continuous-infusion vancomycin (CIV) may be associated with a lower risk of vancomycin-associated nephrotoxicity compared with IIV, but studies comparing safety of both dosing strategies are lacking.

OBJECTIVES

To compare the risk of nephrotoxicity with CIV versus IIV when target concentration ranges were the same with both dosing modalities.

METHODS

A retrospective multicentre matched cohort study of admitted patients between 1 January 2010 and 31 December 2016 was completed. Adult patients who received ≥48 h of vancomycin with at least one steady-state vancomycin concentration were eligible. The primary outcome was to compare the rates of nephrotoxic risk and renal injury, defined by the RIFLE criteria, between CIV and IIV.

RESULTS

Of 2136 patients who received vancomycin during the study period, 146 CIV patients were eligible and matched to 146 IIV patients. After adjustment of potential confounders, CIV was found to have a lower odds of developing nephrotoxic risk (OR 0.42, 95% CI 0.21-0.98, P = 0.025) and renal injury (OR 0.19, 95% CI 0.05-0.59, P = 0.004).

CONCLUSIONS

CIV is associated with a lower odds of nephrotoxicity compared with IIV when targeting the same concentration range and should be an alternative dosing strategy for patients who will receive prolonged therapy or require >4 g/day to achieve therapeutic levels.

Continuous Versus Intermittent Infusion of Vancomycin and the Risk of Acute Kidney Injury in Critically Ill Adults: A Systematic Review and Meta-Analysis

OBJECTIVES

Critically ill patients routinely receive vancomycin as empiric antibiotic therapy. A continuous infusion administration strategy may be superior to intermittent infusion by minimizing peak concentrations and variability thereby optimizing safety. We performed a systematic review and meta-analysis to investigate the impact of vancomycin infusion strategy on acute kidney injury in critically ill adults.

DATA SOURCES

A systematic search of MEDLINE, CINAHL, Web of Science, International Pharmaceutical Abstracts, and Google Scholar was undertaken.

STUDY SELECTION

We included randomized controlled trials and observational studies evaluating acute kidney injury in critically ill adults comparing vancomycin administered by intermittent and continuous infusion. Secondary outcomes included mortality and pharmacokinetic target attainment.

DATA EXTRACTION

Eleven studies were identified for analysis with baseline demographics, endpoints, protocol definitions, and outcomes extracted.

DATA SYNTHESIS

When compared with intermittent infusion, continuous infusion was associated with a reduction in acute kidney injury in critically ill adults (odds ratio, 0.47; 95% CI, 0.34-0.65) and a 2.6 greater odds of pharmacokinetic target attainment (odds ratio, 2.63; 95% CI, 1.52-4.57). No difference in mortality was observed (odds ratio, 1.04; 95% CI, 0.80-1.35).

CONCLUSIONS

When administered via a continuous infusion, vancomycin is associated with a 53% reduction in the odds of acute kidney injury and a 2.6-fold higher odds of pharmacokinetic target attainment when compared with intermittent infusion without influencing overall mortality.

The Emperor's New Clothes: PRospective Observational Evaluation of the Association Between Initial VancomycIn Exposure and Failure Rates Among ADult HospitalizEd Patients With Methicillin-resistant Staphylococcus aureus Bloodstream Infections (PROVIDE)

BACKGROUND

Vancomycin is the most commonly administered antibiotic in hospitalized patients, but optimal exposure targets remain controversial. To clarify the therapeutic exposure range, this study evaluated the association between vancomycin exposure and outcomes in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia.

METHODS

This was a prospective, multicenter (n = 14), observational study of 265 hospitalized adults with MRSA bacteremia treated with vancomycin. The primary outcome was treatment failure (TF), defined as 30-day mortality or persistent bacteremia ≥7 days. Secondary outcomes included acute kidney injury (AKI). The study was powered to compare TF between patients who achieved or did not achieve day 2 area under the curve to minimum inhibitory concentration (AUC/MIC) thresholds previously found to be associated with lower incidences of TF. The thresholds, analyzed separately as co-primary endpoints, were AUC/MIC by broth microdilution ≥650 and AUC/MIC by Etest ≥320.

RESULTS

Treatment failure and AKI occurred in 18% and 26% of patients, respectively. Achievement of the prespecified day 2 AUC/MIC thresholds was not associated with less TF. Alternative day 2 AUC/MIC thresholds associated with lower TF risks were not identified. A relationship between the day 2 AUC and AKI was observed. Patients with day 2 AUC ≤515 experienced the best global outcomes (no TF and no AKI).

CONCLUSIONS

Higher vancomycin exposures did not confer a lower TF risk but were associated with more AKI. The findings suggest that vancomycin dosing should be guided by the AUC and day 2 AUCs should be ≤515. As few patients had day 2 AUCs <400, further study is needed to define the lower bound of the therapeutic range.

Vancomycin Dosing Practices among Critical Care Pharmacists: A Survey of Society of Critical Care Medicine Pharmacists

Introduction

Critically ill patients and their pharmacokinetics present complexities often not considered by consensus guidelines from the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists. Prior surveys have suggested discordance between certain guideline recommendations and reported infectious disease pharmacist practice. Vancomycin dosing practices, including institutional considerations, have not previously been well described in the critically ill patient population.

Objectives

To evaluate critical care pharmacists' self-reported vancomycin practices in comparison to the 2009 guideline recommendations and other best practices identified by the study investigators.

Methods

An online survey developed by the Research and Scholarship Committee of the Clinical Pharmacy and Pharmacology (CPP) Section of the Society of Critical Care Medicine (SCCM) was sent to pharmacist members of the SCCM CPP Section practicing in adult intensive care units in the spring of 2017. This survey queried pharmacists' self-reported practices regarding vancomycin dosing and monitoring in critically ill adults.

Results

Three-hundred and sixty-four responses were received for an estimated response rate of 26%. Critical care pharmacists self-reported largely following the 2009 vancomycin dosing and monitoring guidelines. The largest deviations in guideline recommendation compliance involve consistent use of a loading dose, dosing weight in obese patients, and quality improvement efforts related to systematically monitoring vancomycin-associated nephrotoxicity. Variation exists regarding pharmacist protocols and other practices of vancomycin use in critically ill patients.

Conclusion

Among critical care pharmacists, reported vancomycin practices are largely consistent with the 2009 guideline recommendations. Variations in vancomycin dosing and monitoring protocols are identified, and rationale for guideline non-adherence with loading doses elucidated.

Interventions Targeting the Prescribing and Monitoring of Vancomycin for Hospitalized Patients: A Systematic Review Protocol

INTRODUCTION

Vancomycin remains one of our essential antibiotics after fifty years of treating serious infections such as methicillin-resistant Staphylococcus aureus. Vancomycin, unlike many other antibiotic agents, requires individualized dosing and monitoring of serum drug levels to ensure it is efficacious, to minimize toxicity, and to limit the development of antibiotic resistance. These issues have led to numerous vancomycin clinical practice guidelines being published in recent years including several key national guidelines. Significant resources are invested during the development of such guidelines; however, there is often little or no information about how such guidelines or other vancomycin practice improvement initiatives should be implemented. The aim of this systematic review is to identify and evaluate the effect of interventions using education, guideline implementation, and dissemination of educational resources that have sought to improve therapeutic drug monitoring and dosing of vancomycin.

METHODS

A systematic review of the literature will be conducted for RCTs and observational studies where a vancomycin guideline or practice improvement initiative has been implemented. Electronic databases to be searched are PubMed, Medline, CINAHL, EMBASE and the Cochrane Library of Systematic Reviews. The population will be patients who have had intravenous vancomycin prescribed and monitored in hospital. The interventions will be education, implementation of guidelines or protocols, dissemination of educational materials (printed or electronic) or multifaceted interventions of the above. The comparator will be patients who have had standard-care prescribing and monitoring of vancomycin. Outcomes will be changes in prescribing and ordering of vancomycin serum tests, and serum levels attained in patients as well as reported nephrotoxicity. Two reviewers will be involved in the quality assessment and extraction of data. The Scottish Intercollegiate Guidelines Network checklist for RCTs will be used. Studies that are not randomized will be assessed for quality using the validated ROBINS-I (risk of bias in non-randomized studies of interventions) tool.

DISCUSSION

This systematic review will identify interventions that have been used to implement guidelines and clinical practice initiatives for vancomycin. The findings of this review may be informative to those involved with the implementation of vancomycin clinical practice guidelines. Systematic review registration: PROSPERO: CRD42016049147.

Sustained improvement in vancomycin dosing and monitoring post-implementation of guidelines: Results of a three-year follow-up after a multifaceted intervention in an Australian teaching hospital

INTRODUCTION

Despite vancomycin being in use for over half-a-century, it is still not dosed or monitored appropriately in many centers around the world. The objective of this study was to determine the effectiveness of a multifaceted intervention to implement a vancomycin dosing and monitoring guideline across multiple medical and surgical units over time.

METHODS

This was an observational before-and-after interventional cohort study. The pre-intervention period was August to December 2010-2011 and the post-intervention period was September to November 2012-2014. The implementation strategy comprised: face-to-face education, online continuing medical education, dissemination of pocket guideline and email reminder. Outcome measures included: appropriate prescribing of loading and maintenance doses, therapeutic drug monitoring, time to attain target range and nephrotoxicity.

RESULTS

Post-implementation prescribing of loading doses increased (10.4%-43.6%, P=<0.001), guideline adherent first maintenance dose (44%-68.4% P = 0.04), correct dose adjustment from (53.1%-72.2%, P = 0.009). Beneficial effects pre and post-implementation were observed for adherent timing of initial concentration (43.2%-51.9%, P = 0.01), concentrations in target range (32.6%-44.1%, P = 0.001), time to target range (median 6-4 days, P=<0.001), potentially nephrotoxic concentrations (30.7%-20.9%, P=<0.001) and nephrotoxicity (10.4%-6.8%, P=<0.001).

CONCLUSIONS

A multifaceted intervention to implement a vancomycin dosing and monitoring guideline significantly improved prescribing, monitoring, pharmacokinetic and safety outcomes for patients treated with vancomycin over an extended period. However, increased guideline adoption by clinicians is required to maximize and prolong the utility of this important agent.

Junior doctors' preparedness to prescribe, monitor, and treat patients with the antibiotic vancomycin in an Australian teaching hospital

PURPOSE

We aimed to assess the preparedness of junior doctors to use vancomycin, and to determine whether attending an educational session and being provided pocket guidelines were associated with self-reported confidence and objective knowledge.

METHODS

This was a 2-component cross-sectional study. A 60-minute educational session was implemented and pocket guidelines were provided. Preparedness was evaluated by a self-reported confidence survey in the early and late stages of each training year, and by continuing medical education (CME) knowledge scores.

RESULTS

Self-confidence was higher among those later in the training year (n=75) than in those earlier (n=120) in the year for all questions. In the late group, vancomycin education was associated with higher self-confidence regarding the frequency of therapeutic drug monitoring (P=0.02) and dose amendment (P=0.05); however, the confidence for initial monitoring was lower (P<0.05). Those with pocket guidelines were more confident treating patients with vancomycin (P<0.001), choosing initial (P=0.01) and maintenance doses (P<0.001), and knowing the monitoring frequency (P=0.03). The 85 respondents who completed the knowledge assessment scored a mean±standard deviation of 8.55±1.55 on 10 questions, and the interventions had no significant effect.

CONCLUSION

Attending an educational session and possessing pocket guidelines were associated with preparedness, as measured by higher self-reported confidence using vancomycin. High knowledge scores were attained following CME; however attending an educational session or possessing pocket guidelines did not significantly increase the knowledge scores. Our findings support providing educational sessions and pocket guidelines to increase self-confidence in prescribing vancomycin, yet also highlight the importance of evaluating content, format, and delivery when seeking to improve preparedness to use vancomycin through education.

The impact of a pilot continuing professional development module on hospital pharmacists' preparedness to provide contemporary advice on the clinical use of vancomycin

BACKGROUND

Revised international clinical guidelines for the antibiotic vancomycin have changed the advice pharmacists need to provide to medical and nursing colleagues.

OBJECTIVES

(1) To determine the self-reported confidence of hospital pharmacists to provide contemporary advice on vancomycin and (2) to evaluate hospital pharmacists' knowledge to provide contemporary advice on vancomycin following a pilot continuing professional development (CPD) module.

METHODS

The study was a prospective two-phase design in an Australian teaching hospital. Phase one: a survey of pharmacist self-reported confidence to eight questions on providing contemporary advice on vancomycin. Responses were recorded using a Likert scales. Phase two: The provision of a pilot online CPD module on vancomycin containing knowledge-based assessment based on a clinical vignette. Likert scales recorded self-reported confidence were reported as median and interquartile range (IQR). Knowledge assessment was reported using descriptive statistics. The main outcome measure were the self-reported confidence, and knowledge of pharmacists regarding provision of contemporary advice on clinical vancomycin use.

RESULTS

Response rates for surveys; confidence n = 35 (72.9 %) and knowledge n = 31 (58.5 %). Phase one: confidence was highest regarding vancomycin dosing and monitoring with 71.4-81.6 % of respondents agreeing or strongly agreeing that they were confident in these domains. Respondents agreeing or strongly agreeing were least confident regarding intravenous administration and infusion related reactions, 57.1 and 45.7 % respectively. Respondents who provided advice on vancomycin >10 times in the prior 12 months reported significantly higher confidence in; therapeutic range 1 (IQR 1-2) versus 2 (IQR 1-3) p = 0.02; amending dosage based on therapeutic drug monitoring results 2 (IQR 1-3) versus 3 (IQR 2-3) p = <0.001, and providing general advice to prescribers on vancomycin 2 (IQR 1-3) versus 2 (IQR 2-4) p = <0.009. Knowledge questions were answered correctly post CPD by >75 % of pharmacists.

CONCLUSION

Pharmacists' self-reported confidence to managing vancomycin was variable but generally high. Knowledge scores were consistently high after pharmacists completed a pilot CPD module on vancomycin. These data provides impetus for a randomised controlled study across multiple sites to determine the extent to which pharmacist knowledge on vancomycin can be attributed to completion of an online CPD.

Pharmacist-led implementation of a vancomycin guideline across medical and surgical units: impact on clinical behavior and therapeutic drug monitoring outcomes

Background

Vancomycin is the antibiotic of choice for the treatment of serious infections such as methicillin-resistant Staphylococcus aureus (MRSA). Inappropriate prescribing of vancomycin can lead to therapeutic failure, antibiotic resistance, and drug toxicity.

Objective

To examine the effectiveness of pharmacist-led implementation of a clinical practice guideline for vancomycin dosing and monitoring in a teaching hospital.

Methods

An observational pre–post study design was undertaken to evaluate the implementation of the vancomycin guideline. The implementation strategy principally involved education, clinical vignettes, and provision of pocket guidelines to accompany release of the guideline to the hospital Intranet. The target cohort for clinical behavioral change was junior medical officers, as they perform the majority of prescribing and monitoring of vancomycin in hospitals. Assessment measures were recorded for vancomycin prescribing, therapeutic drug monitoring, and patient outcomes.

Results

Ninety-nine patients, 53 pre- and 46 post-implementation, were included in the study. Prescribing of a loading dose increased from 9% to 28% (P=0.02), and guideline adherence to starting maintenance dosing increased from 53% to 63% (P=0.32). Dose adjustment by doctors when blood concentrations were outside target increased from 53% to 71% (P=0.12), and correct timing of initial concentration measurement increased from 43% to 57% (P=0.23). Appropriately timed trough concentrations improved from 73% to 81% (P=0.08). Pre-dose (trough) concentrations in target range rose from 33% to 44% (P=0.10), while potentially toxic concentrations decreased from 32% to 21% (P=0.05) post-implementation. Infection cure rates for patients increased from 85% to 96% (P=0.11) after the guideline was implemented.

Conclusion

The implementation strategy employed in this study demonstrated potential effectiveness, and should prompt additional larger studies to optimize strategies that will translate into improved clinical practice using vancomycin.

Observational clinical study on the effects of different dosing regimens on vancomycin target levels in critically ill patients: Continuous versus intermittent application

Different dosing regimens for vancomycin are in clinical use: intermittent infusion and continuous administration. The intention of using these different dosing regimens is to reduce toxicity, to achieve target levels faster and to avoid treatment failure. The aim of this phase IV study was to compare safety and effectiveness in both administration regimens. The study was conducted in 2010 and 2011 in three postoperative intensive care units (ICUs) in a tertiary care university hospital in Berlin, Germany. Adult patients with vancomycin therapy and therapeutic drug monitoring were included. Out of 675 patients screened, 125 received vancomycin therapy, 39% with intermittent and 61% with continuous administration. Patients with continuous administration achieved target serum levels significantly earlier (median day 3 versus 4, p=0.022) and showed fewer sub-therapeutic serum levels (41% versus 11%, p<0.001). ICU mortality rate, duration of ICU stay and duration of ventilation did not differ between groups. Acute renal failure during the ICU stay occurred in 35% of patients with intermittent infusion versus 26% of patients with continuous application (p=0.324). In conclusion, continuous administration of vancomycin allowed more rapid achievement of targeted drug levels with fewer sub-therapeutic vancomycin levels observed. This might indicate that patients with more severe infections or higher variability in renal function could benefit from this form of administration.

A Review of Novel Combinations of Colistin and Lipopeptide or Glycopeptide Antibiotics for the Treatment of Multidrug-Resistant Acinetobacter baumannii

As antibiotic resistance continues to increase among Gram-negative organisms such as Acinetobacter baumannii there is a growing need for novel therapies to overcome these resistance mechanisms. Antibiotics active against multidrug-resistant A. baumannii (MDRAB) are few, and agents in development are primarily active against other multidrug-resistant Gram-negative organisms. The combinations of colistin and antimicrobials such as glycopeptides and lipopeptides are unique potential treatment modalities against MDRAB. For both lipopeptides and glycopeptides in vitro data have demonstrated significant synergy, resulting in rapid bactericidal activity in time-kill curves. Several invertebrate in vivo models have also demonstrated increased survival compared to colistin alone. Currently, very little clinical data have focused on using these combinations for infections caused exclusively by multidrug-resistant Gram-negatives. The combination of vancomycin and colistin has been studied with conflicting results regarding both improved outcomes and risk of nephrotoxicity. Although in vitro and in vivo models have proved promising, further investigation is required to provide clinical data necessary to support the use of these combinations. The objective of this review is to summarize literature currently available for the novel combination of lipopeptides or glycopeptides with colistin for the treatment of A. baumannii, in particular MDRAB.