Use of vancomycin in high-flux hemodialysis: experience with 130 courses of therapy

Vancomycin Dosing in Patients on Intermittent Hemodialysis-A Retrospective Study

PURPOSE

To determine the incidence of therapeutic target attainment using a three-times per week protocol for vancomycin therapy given during the last hour of intermittent hemodialysis (HD).

METHODS

A single-center retrospective cohort study was conducted of patient medical records in a remote dialysis center from January 2017 to July 2023. Adult patients with chronic kidney disease stage 5 on ≥3 months of intermittent HD who had received a course of vancomycin therapy with ≥1 serum vancomycin concentration recorded were included. Demographic and dosing data were collected. Clinician adherence with the dosing protocol and attainment of the therapeutic target (trough concentration within 15-20 mg/L) following the loading and maintenance doses were assessed. Factors associated with target nonattainment following the loading dose were analyzed, and the 48- and 72-h maintenance dosing intervals were analyzed for target nonattainment.

FINDINGS

A total of 98 vancomycin courses (67 patients) were available for analysis. Only 38% of the loading doses were prescribed as per protocol. Following the loading dose, 25% of trough concentrations achieved the therapeutic target concentration (15-20 mg/L), 25% returned a supra-therapeutic concentration (>20 mg/L) and 50% were sub-therapeutic (<15 mg/L). When compared with those achieving target, sub-therapeutic concentrations were associated with a lower loading dose (median 16.6 vs 20.0 mg/kg, P < 0.002), and supra-therapeutic concentrations had a shorter dosing interval between the loading dose and first maintenance dose (median 31.5 vs 39.0 h, P = 0.06). Of the 201 maintenance trough concentrations collected, 65% were therapeutic, 21% were sub-therapeutic and 14% were supra-therapeutic, with an overall median trough concentration of 17.3 mg/L. As the treatment duration increased, an increase was seen in the number of dose adjustments required to achieve the target trough concentration. The 48-h dosing interval was associated with more supra-therapeutic concentrations and the 72-h interval was associated with more sub-therapeutic concentrations (df = 2, P = 0.022).

IMPLICATIONS

We have identified a high rate of target nonattainment for HD patients on a three times a week vancomycin dosing regimen. We recommend a loading dose of 20 to 25 mg/kg irrespective of the indication and a better-defined dosing interval after the loading dose. A higher maintenance dose should be prescribed when the time to next dialysis session is 72 h. Further pharmacokinetic studies are needed to assess factors influencing target concentration attainment following the maintenance doses and to determine an optimal dosing regimen.

Practices, Knowledge, and Attitudes of Nephrologists Towards Prescribing and Monitoring Vancomycin at Dialysis Centers

BACKGROUND

Vancomycin dosing protocols are varied in the literature for hemodialysis patients. This study sought to determine nephrologists' practices, knowledge, attitudes, and barriers toward prescribing and monitoring vancomycin at dialysis centers.

METHODS

A cross-sectional and multi-center study was conducted in Kuwait using a validated self-administered questionnaire among 168 nephrologists. Descriptive and comparative analyses were performed using SPSS (version 28).

RESULTS

The response rate was 75% (n = 126). Over half of nephrologists frequently prescribed a vancomycin loading dose of 1000 mg (53.2%) and a maintenance dose of 500 mg (51.6%) to all patients. Their overall median (IQR) percentage knowledge about the therapeutic monitoring of vancomycin was 66.7% (33.3) and was found to be higher in nephrologists aged ≤ 40 years and in registrars/senior registrars (p < 0.05). Their overall median (IQR) attitude score was 4.0 (1.0) [positive attitude]. Nephrologists with > 15 years of practice experience expressed higher attitudes (p < 0.05). The top two perceived barriers were a lack of clear local hospital/national guidelines (60.3%) for vancomycin dosing in dialysis and inconsistencies among different dosing references and guidelines (51.6%).

CONCLUSION

Findings showed that nephrologists have varying practices, moderate knowledge, and positive attitudes toward prescribing and monitoring vancomycin and highlight the need for interventions to overcome the perceived barriers.

Comparison of antimicrobial dosing recommendations in patients receiving intermittent hemodialysis among drug information resources

WHAT IS KNOWN AND OBJECTIVE

Tertiary drug information resources are frequently consulted for the optimal antimicrobial dosing in intermittent hemodialysis (IHD) patients. Yet, significant discrepancy may exist in dosing recommendations between resources. This study was to evaluate the consistency of antimicrobial dosing recommendations in IHD among four different drug information resources and the relevance of referenced pharmacokinetic studies.

METHODS

Dosing recommendations of 29 commonly prescribed antimicrobials in IHD patients were collected from Micromedex, LexiComp, Clinical Pharmacology and Drug Prescribing in Renal Impairment to compare dosing categorization and the total daily dose (TDD). Significant dosing discrepancies were defined as ≥30% difference. Referenced pharmacokinetic studies were evaluated for their relevance in current practice, using sample size, hemodialyzer types, the use of optimal pharmacodynamic targets and the consideration of different interdialytic dosing periods.

RESULTS AND DISCUSSION

A significant variation was found both in dosing categorization and recommended doses between resources. Seventeen drugs were compared for TDD with significant dosing discrepancy in 8 drugs. Among 42 referenced pharmacokinetic studies, 40 were evaluated. Mean patient numbers of pharmacokinetic studies were 13 ranging from 3 to 70. Sixty per cent of studies utilized contemporary hemodialyzers (e.g., high-flux and/or high efficiency). The optimal pharmacodynamic targets and the impact of different interdialytic intervals were assessed only in 27.5% and 7.5% respectively.

WHAT IS NEW AND CONCLUSION

Inconsistent antimicrobial dosing recommendations for IHD patients exist among four well-established resources. Many referenced pharmacokinetic studies utilized outdated or less pharmacodynamically relevant study methods. Newer studies are warranted to reflect contemporary dialysis practice and assess its impact on optimal antimicrobial dosing.

Pharmacokinetics of Vancomycin in Pediatric Patients Receiving Intermittent Hemodialysis or Hemodiafiltration

INTRODUCTION

Vancomycin is a common antibiotic used to treat hemodialysis (HD) or hemodiafiltration (HDF)-related infections in pediatric patients, but optimal dosing remains unknown. This is the first observational study to characterize the pharmacokinetics and evaluate dosing of vancomycin in this population.

METHODS

Eligible patients received IV vancomycin 10 mg/kg per dose postdialysis followed by a series of serum vancomycin concentrations collected before, immediately after, 1 hour after, and 4 hours after dialysis. The pharmacokinetic parameters were estimated using 1- and 2-compartment models and a nonlinear least-squares algorithm.

RESULTS

Among 42 vancomycin courses in 16 patients, 1 compartment model had the best fit for observed data. The net drug removal was 43 ± 13% (39% for HD and 50% for HDF) from an average 3-hour HD/HDF session. The mean elimination constant was 0.28 h-1 (standard deviation [SD], 0.11 h-1) during the intradialytic period compared with 0.0049 h-1 (SD, 0.004 h-1) when off dialysis. The mean volume of distribution was 0.65 (SD, 0.19) L/kg. Duration of dialysis session and mode of dialysis (HD vs. HDF) were significant predictors of vancomycin pharmacokinetic parameters. Half-life was shorter for HDF compared with HD (2.1 vs. 3.5 hours).

CONCLUSIONS

Based on the simulations, an initial vancomycin dose of 10 mg/kg per dose and redosing postdialysis was optimal to achieve a vancomycin concentration range of 5 to 12 mg/L at 4 hours postdialysis and 24-hour area under the curve over minimum inhibitory concentration of ≥400 hours. Therapeutic drug monitoring is necessary to account for residual variability in vancomycin elimination in pediatric patients receiving HD/HDF.

Evaluation and Development of Vancomycin Dosing Schemes to Meet New AUC/MIC Targets in Intermittent Hemodialysis Using Monte Carlo Simulation Techniques

Published vancomycin dosing recommendations for patients receiving maintenance hemodialysis were not designed to meet newly recommended 24-hour area under the curve/minimum inhibitory concentration (AUC_24h /MIC) pharmacokinetic/pharmacodynamic targets. The aims of this study were to predict pharmacokinetic/pharmacodynamic target attainment rates with a commonly used vancomycin regimen and to design a new dosing scheme incorporating therapeutic drug monitoring (TDM) to maximize target attainment in patients receiving vancomycin and hemodialysis with high- or low-flux hemodialyzers. Vancomycin pharmacokinetic- and dialysis-specific parameters were incorporated into Monte Carlo simulations (MCS). A commonly used vancomycin regimen was modeled to determine its likelihood of attaining AUC_24h /MIC targets for 1 week of thrice-weekly hemodialysis treatments. MCS was then used to develop optimal initial vancomycin dosing for patients receiving intradialytic or postdialytic vancomycin administration with either high- or low-flux hemodialyzers. Finally, a new MCS model incorporating TDM was built to further optimize the probability of pharmacokinetic/pharmacodynamic target attainment. Traditional vancomycin dosing methods are unlikely to meet AUC_24h /MIC targets. Vancomycin doses necessary to attain AUC_24h /MIC targets are significantly influenced by hemodialyzer permeability and whether vancomycin is administered intradialytically or after hemodialysis. Depending on dialyzer type and whether vancomycin is administered during or after hemodialysis, loading doses of 25 to 35 mg/kg followed by maintenance doses of 7.5 to 15 mg/kg are necessary to reach minimum AUC_24h /MIC targets in 90% of virtual patients. For a 3-day interdialytic period, a 30% higher maintenance dose is required to maintain target attainment. Dosing based on a single vancomycin serum concentration obtained prior to the second dialysis session greatly enhances the probability of target attainment.

Retention of beneficial molecules and coagulation factors during haemodialysis and haemodiafiltration

Middle molecules (MMs) are associated with the pathology of uraemia, and are not effectively removed by standard extracorporeal treatments. Increased convection used in haemodiafiltration (HDF) can enhance the removal of MMs; however, high-volume HDF is not available to all patients. The new medium cut-off (MCO) membrane has been developed to allow increased removal of MMs using standard haemodialysis (HD). Improved removal of MMs has been shown with the MCO membrane compared with standard high-flux dialysers, but it is not known whether the increased pore size affects the retention of commonly used medications or that of coagulation factors in dialysis patients. Using an in vitro model, the retention of erythropoietin, heparin, insulin, vancomycin and several coagulation factors (Factors II, VII and X, protein C and antithrombin III) was investigated with the MCO membrane dialyser, compared with high-flux dialysers with polysulfone (in HDF) or polyethersulfone membranes (in HD and HDF). The retention of all molecules investigated was comparable between the MCO membrane and the high-flux dialysers. Results from the in vitro studies suggest that switching from a high-flux dialyser to the MCO membrane should not require changes to the medication dosing or anti-coagulation protocols of dialysis patients.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Evaluation of Factors which Influence Mortality in Gram-positive Bacteremia in Hemodialysis Patients

Vascular access infection is one of the major contributors to hemodialysis (HD) patient morbidity and mortality. There is a paucity of consensus guidelines on vancomycin use in the HD population. The primary objective of this study was to determine if vancomycin serum concentrations were associated with positive outcomes in HD patients with Gram-positive bacteremia. A retrospective cohort study conducted at a 443-bed tertiary teaching county hospital from January 1, 2010 to January 1, 2016 was performed. Patients aged 18-89, with chronic renal failure on hemodialysis who presented with positive blood cultures with Gram-positive bacteria and received intravenous vancomycin for at least 24 hours were evaluated. A multivariate analysis was utilized comparing factors related to outcomes including Simplified Acute Physiology Score II (SAPS II), loading dose, 30-day mortality and vancomycin serum concentrations. A total of 139 patients were obtained, 90 of whom had documented pre-dialysis serum vancomycin concentrations. A multivariate analysis showed that a lower SAPS II score [OR 1.220 (95% CI: 1.086-1.370, p < 0.0001)], a higher loading dose/kg [OR 0.7911 (0.6302-0.9929, p = 0.0239)], and pre-dialysis concentrations between 15 and 20 mcg/mL [0.05437 (95% CI: 0.0033-0.8891, p = 0.0099)] were associated with decreased mortality (overall multivariate model, p < 0.0001). When patient acuity and loading dosing are taken into account, pre-dialysis vancomycin serum concentrations between 15 and 20 mcg/mL were associated with decreased mortality in Gram-positive bacteremic intermittent HD patients. Further prospective studies are needed to assess whether targeting a pre-dialysis serum vancomycin concentration of 15-20 mcg/mL can improve mortality.

The ratio of pre-dialysis vancomycin trough serum concentration to minimum inhibitory concentration is associated with treatment outcomes in methicillin-resistant Staphylococcus aureus bacteremia

Background

Vancomycin is a standard treatment for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, and its efficacy is closely linked to the recommended serum trough concentration of 15–20 mg/L. However, it is unknown how the pre-dialysis trough serum concentration (C_pre-HD) correlates with MRSA eradication in renal failure patients undergoing intermittent hemodialysis (HD).

Objective

To evaluate the relationship between C_pre-HD and the treatment outcomes in this population.

Materials and methods

A retrospective study was conducted to enroll renal failure patients undergoing HD who had received vancomycin treatment for MRSA bacteremia during January 2013 to June 2016. Treatment failure was defined as persistent bacteremia after ≥ 7 days of vancomycin therapy or recurrent MRSA infection within 30 days. Patient characteristics, vancomycin dosing regimen, C_pre-HD, vancomycin minimum inhibitory concentration (MIC), and subsequent culture data were reviewed. The receiver operating characteristic (ROC) curve was used to find the optimal cut-off point of C_pre-HD.

Results

42 patients were enrolled and 64% had treatment failure. Although there were no significant differences in demographics or C_pre-HD between the two groups, C_pre-HD/MIC was significantly higher in the success group than that in the failure group (22.80±10.90 vs. 14.94±6.11, p = 0.019). The area under the ROC curve was 0.74, while the sensitivity, specificity, positive predictive value, and negative predictive value were 67%, 78%, 62.5%, and 81%, respectively, at the optimal C_pre-HD/MIC of ≧ 18.6.

Conclusions

C_pre-HD/MIC was associated with vancomycin treatment outcome in MRSA bacteremia, and targeting to achieve a C_pre-HD/MIC of ≧ 18.6 may improve treatment outcomes in renal failure patients who are on intermittent HD.

The Nephrotoxicity of Vancomycin

Vancomycin use is often associated with nephrotoxicity. It remains uncertain, however, to what extent vancomycin is directly responsible, as numerous potential risk factors for acute kidney injury frequently coexist. Herein, we critically examine available data in adult patients pertinent to this question. We review the pharmacokinetics/pharmacodynamics of vancomycin metabolism. Efficacy and safety data are discussed. The pathophysiology of vancomycin nephrotoxicity is considered. Risk factors for nephrotoxicity are enumerated, including the potential synergistic nephrotoxicity of vancomycin and piperacillin‐tazobactam. Suggestions for clinical practice and future research are given.

Prevention and Therapy of Acute Kidney Injury in the Developing World

Timely recognition of patients at risk or with possible acute kidney injury (AKI) is essential for early intervention to minimize further damage and improve outcome. Initial management of patients with suspected and persistent AKI should include thorough clinical assessment of all patients with AKI to identify reversible factors, including fluid volume status, potential nephrotoxins, and an assessment of the underlying health of the kidney. Based on these assessments, early interventions to provide appropriate and adequate fluid resuscitation while avoiding fluid overload, removal of nephrotoxins, and adjustment of drug doses according to the level of kidney function derangement are important. The judicious use of diuretics for fluid overload and/or in cardiac decompensated patients and introduction of early enteral nutritional support need to be considered to improve outcomes in AKI. Although these basic principles are well recognized, their application in clinical practice in low resource settings is often limited due to lack of education, availability of resources, and lack of trained personnel, which limits access to care. We report the consensus recommendations of the 18th Acute Dialysis Quality Initiative meeting in Hyderabad, India, on strategies to evaluate patients with suspected AKI and initiate measures for prevention and management to improve outcomes, particularly in low resource settings. These recomendations provide a framework for caregivers, who are often primary care physicians, nurses, and other allied healthcare personnel, to manage patients with AKI in resource poor countries.

Predicting Maintenance Doses of Vancomycin for Hospitalized Patients Undergoing Hemodialysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus is a leading cause of death in patients undergoing hemodialysis. However, controversy exists about the optimal dose of vancomycin that will yield the recommended pre-hemodialysis serum concentration of 15-20 mg/L.

OBJECTIVE

To develop a data-driven model to optimize the accuracy of maintenance dosing of vancomycin for patients undergoing hemodialysis.

METHODS

A prospective observational cohort study was performed with 164 observations obtained from a convenience sample of 63 patients undergoing hemodialysis. All vancomycin doses were given on the floor after completion of a hemodialysis session. Multivariate linear generalized estimating equation analysis was used to examine independent predictors of pre-hemodialysis serum vancomycin concentration.

RESULTS

Pre-hemodialysis serum vancomycin concentration was independently associated with maintenance dose (B = 0.658, p < 0.001), baseline pre-hemodialysis serum concentration of the drug (B = 0.492, p < 0.001), and interdialytic interval (B = -2.133, p < 0.001). According to the best of 4 models that were developed, the maintenance dose of vancomycin required to achieve a pre-hemodialysis serum concentration of 15-20 mg/L, if the baseline serum concentration of the drug was also 15-20 mg/L, was 5.9 mg/kg with interdialytic interval of 48 h and 7.1 mg/kg with interdialytic interval of 72 h. However, if the baseline pre-hemodialysis serum concentration was 10-14.99 mg/L, the required dose increased to 9.2 mg/kg with an interdialytic interval of 48 h and 10.0 mg/kg with an interdialytic interval of 72 h.

CONCLUSIONS

The maintenance dose of vancomycin varied according to baseline pre-hemodialysis serum concentration of the drug and interdialytic interval. The current practice of targeting a pre-hemodialysis concentration of 15-20 mg/L may be difficult to achieve for the majority of patients undergoing hemodialysis.

Vancomycin dosing and monitoring for patients with end-stage renal disease receiving intermittent hemodialysis

PURPOSE

Vancomycin dosing and monitoring algorithms for patients with end-stage renal disease (ESRD) receiving intermittent hemodialysis are reviewed.

SUMMARY

Vancomycin is one of the most commonly administered antimicrobial agents in adult patients with ESRD receiving intermittent hemodialysis. However, despite the availability of many published studies, the single best method of vancomycin administration in this population remains unclear. Many studies evaluating vancomycin dosing in adult patients with ESRD receiving intermittent hemodialysis were limited by a small sample size, inappropriate therapeutic targets, older hemodialysis modalities (e.g., low-flux intermittent hemodialysis), and inconsistencies in the timing of dosing or therapeutic drug monitoring. Pharmacokinetic variables that must be accounted for include a prolonged distribution phase, a redistribution phase and rebound effect after completion of hemodialysis, patient weight, residual renal function, and nonrenal clearance. Optimal vancomycin dosing recommendations are needed, but clinicians should always consider patient-specific variables, the timing of vancomycin administration, the timing of serum vancomycin concentrations, and technical aspects of the dialysis procedure when creating a dosing regimen.

CONCLUSION

Individualized vancomycin dosing regimens and therapeutic drug monitoring are necessary for patients with ESRD receiving intermittent hemodialysis to ensure that goal serum vancomycin levels are reached to adequately treat an infection.

Application of Intrawound Vancomycin Powder during Spine Surgery in a Patient with Dialysis-Dependent Renal Failure

Surgical site infections (SSIs) after spinal surgery are a serious complication that can be minimized with prophylaxis. Vancomycin is a common agent used in the prevention of SSI. Given that vancomycin is renally cleared, its use requires careful observation in dialysis-dependent patients due to toxicity at supratherapeutic levels. Since minimum inhibitory concentrations (MICs) for vancomycin have increased due to the emergence of resistant pathogens, the use of vancomycin in such patients is further complicated. Local instillation of vancomycin powder is thought to provide additional protection against SSI and have lower systemic absorption. We present a patient with end-stage renal disease that developed progressively debilitating cervical spondylotic myelopathy necessitating multilevel laminectomy and instrumented fusion. Prior to closure, 1 gram of vancomycin powder was sprinkled into the surgical incision. Postoperative serum vancomycin levels were well below those associated with nephrotoxicity and ototoxicity. Based on this experience, we reviewed the relevant guidelines that were designed to prevent postoperative infections in such dialysis-dependent patients. Intrawound application of vancomycin may be a legitimate and safe option for SSI prophylaxis in patients with renal failure on dialysis.

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.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Hemodialysis Catheter-related Infection: Prophylaxis, Diagnosis and Treatment

Purpose

Infectious complications associated with central venous catheters (CVCs) are a major source of morbidity and mortality among hemodialysis (HD) patients. This review aims to discuss prevention, diagnosis criteria and management of CVC-related infections in HD patients.

Methods

We searched Medline for articles published in the last 10 years, with the keywords “catheter,” “hemodialysis,” “infection,” “treatment,” “diagnosis,” “prophylaxis” and “adults.” Only English language articles were reviewed. We reviewed prophylaxis and surveillance protocols, diagnosis criteria, including new molecular tools, and the management of catheter-related infections, including antibiotic regimen, empiric and according to causal agents, lock therapy, catheter salvage or removal choice and treatment of complications.

Results

To prevent infectious complications, first of all we need to avoid using catheters. If we need CVC, adoption of prophylaxis and surveillance protocols, and antibiotic ointment at the exit site reduce infectious complications. The diagnosis of CVC-related infections should be made with drainage and/or blood cultures. Empiric systemic antibiotics should cover Gram-positive and -negative microorganisms, and final regimen should be based on culture results. In selected cases, salvage of site, by CVC exchange over wire, or salvage of catheter, using antibiotic lock, under the cover of systemic antibiotics, could be attempted.

Conclusions

The best approach to prevent CVC-related infection would be to avoid the use of CVC. However, in patients for whom it is impossible, the adoption of adequate prophylaxis protocols, early diagnosis and effective treatment of infectious complications are essential to improve outcomes.

Pharmacokinetic analysis of antibiotic adsorption (vancomycin and teicoplanin) by the Lixelle extracorporeal unit

PURPOSE

The pharmacokinetic properties of vancomycin (VAN) and teicoplanin (TEC) may be affected by adsorption during hemofiltration as well as hemoperfusion therapies. The aim of this in vitro study was to investigate VAN and TEC removal adsorption kinetics with mass balance analysis by direct hemoperfusion (DHP) with the Lixelle S-35 cartridge (Lixelle, Kaneka Corporation, Tokyo).

METHODS

Mock DHP was performed for 120 min using VAN and TEC solutions (46.08 ± 0.81 and 74.79 ± 1.24 mg/l per N = 6). Clinical plasma antibiotic concentrations were circulated in a closed circuit simulating DHP using an adsorption column (Lixelle S-35) at flow rate of 250 ml/min. Samples were collected at 10, 60, and 120 min through both arterial and venous ports; drug levels were measured with particle enhanced turbidimetric inhibition immunoassay and fluorescence polarization immunoassay. All tests were performed in triplicate.

RESULTS

Results subsequent to DHP at the primary assessment interval for VAN mass was 49.06 ± 1.47 mg, indicating a significant reduction of the starting mass (94.74 ± 1.63 mg). The observed reduction of TEC levels greatly exceeded that of VAN at the first interval (10 min). At 120 min of DHP, the estimated mass adsorption of VAN was 45.68 ± 2.26 mg, while the mesured total TEC mass adsorbed was 126.86 ± 0.91 mg.

CONCLUSIONS

A VAN adsorption plateau indicating the VAN loading dose may be required in patients receiving DHP with the Lixelle S-35. The total TEC mass was adsorbed subsequent to 60 min of circulation, so the loading dose should be closely considered. In addition, the Lixelle S-35 may represent an option as a rescue therapy in accidental overdose of TEC.

Vancomycin: the tale of the vanquisher and the pyrrhic victory

Vancomycin has been the antibiotic of choice in the treatment of methicillin-resistant Staphylococcus aureus infections for decades. But relatively recently, vancomycin-intermediate-susceptible S. aureus (VISA) have been reported. Phenotypically, VISA are characterized by thicker cell walls, requiring higher concentrations of vancomycin for inhibition of bacterial cell growth. Vancomycin-intermediate-susceptible S. aureus represent just the tip of the iceberg of an insidious loss of vancomycin susceptibility in staphylococci. Increasing proportions of S. aureus isolates have higher minimum inhibitory concentrations that are still within the officially susceptible range, a characteristic that is associated with treatment failure. The most important risk factor for decreased vancomycin susceptibility is in vivo selection pressure. To prevent the development of VISA, prolonged or inappropriate use of vancomycin and suboptimal vancomycin levels should be avoided. Trough serum vancomycin concentrations of 15 - 20 mg/L for intermittent dosing and plateau serum vancomycin concentrations of 20 - 25 mg/L for continuous infusions are therefore currently recommended. The widespread clinical application of these intensive dosing regimens has resulted in an increasing awareness of vancomycin-induced nephrotoxicity, which is especially relevant in patients whose renal function is already compromised. This narrow therapeutic-toxic window reinforces the use of rigorous dosing protocols. In hemodialysis, the use of a vancomycin dose calculator permits achievement of target concentrations in most patients. In peritoneal dialysis (PD), intermittent vancomycin dosing regimens often lead to low end-of-dwell concentrations. On the other hand, a continuous vancomycin dosing regimen after a loading dose offers the desired combination of high local levels without toxic systemic levels.

Bacteremia, Sepsis, and Infective Endocarditis Associated with Staphylococcus aureus

Bacteremia and infective endocarditis (IE) are important causes of morbidity and mortality associated with Staphylococcus aureus infections. Increasing exposure to healthcare, invasive procedures, and prosthetic implants has been associated with a rising incidence of S. aureus bacteremia (SAB) and IE since the late twentieth century. S. aureus is now the most common cause of bacteremia and IE in industrialized nations worldwide and is associated with excess mortality when compared to other pathogens. Central tenets of management include identification of complicated bacteremia, eradicating foci of infection, and, for many, prolonged antimicrobial therapy. Evolving multidrug resistance and limited therapeutic options highlight the many unanswered clinical questions and urgent need for further high-quality clinical research.

Antibiotic Dosing in Patients With Acute Kidney Injury: "Enough But Not Too Much"

Increasing evidence suggests that antibiotic dosing in critically ill patients with acute kidney injury (AKI) often does not achieve pharmacodynamic goals, and the continued high mortality rate due to infectious causes appears to confirm these findings. Although there are compelling reasons why clinicians should use more aggressive antibiotic dosing, particularly in patients receiving aggressive renal replacement therapies, concerns for toxicity associated with higher doses are real. The presence of multisystem organ failure and polypharmacy predispose these patients to drug toxicity. This article examines the pharmacokinetic and pharmacodynamic consequences of critical illness, AKI, and renal replacement therapy and describes potential solutions to help clinicians give "enough but not too much" in these very complicated patients.

Subtherapeutic serum vancomycin concentrations during on-line hemodiafiltration

The aim of the study is to study vancomycin serum concentration changes during on-line hemodiafiltration (OL-HDF) and determine whether administration of vancomycin during the last hour of OL-HDF provides therapeutic serum concentrations. Vancomycin was administered intravenously at a dose of 15 mg/kg to 17 chronic hemodialysis patients who were enrolled into two study groups (A and B). In group A patients (n = 11), vancomycin was administered immediately postdialysis. Forty-three hours later, a 4-hour OL-HDF session was performed. Blood samples (S) for vancomycin measurement were drawn before, during, and after the session. In group B patients (n = 6), vancomycin was administered during the last hour of a 4-hour OL-HDF session on Monday. Vancomycin serum concentrations were measured postdialysis, as well as before and after the next two dialysis sessions of the week. In group A patients, mean vancomycin concentrations were reduced by 50% (S(pre): 10.2 ± 1.4 μg/ml, S(post): 5.0 ± 0.9 μg/ml). Vancomycin dialysance was 74.6 ± 29.3 ml/min, while the volume of distribution was 0.42 L/kg. In group B patients, mean vancomycin concentrations before the beginning of Wednesday and Friday dialysis sessions were 3.1 ± 0.7 and 1.4 ± 0.4 μg/ml, respectively. Postdialysis administration of vancomycin followed by OL-HDF resulted in a 50% reduction of vancomycin serum concentrations. Administration during the last treatment hour of OL-HDF results in subtherapeutic vancomycin serum concentrations over the course of the subsequent inter- and intradialytic intervals.

The protective and immunomodulatory effects of hypothalamic proline-rich polypeptide galarmin against methicillin-resistant Staphylococcus aureus infection in mice

The present research summarizes the protective and immunomodulatory activity of hypothalamic proline-rich polypeptide galarmin against methicillin-resistant Staphylococcus aureus (MRSA). The protective effect of galarmin was shown on MRSA-infected animals' survival and weight loss recovery. The immunological impact of galarmin was evaluated in terms of immunocompetent cell recruitment, serum immunoglobulins, complement components C3 and C4, and pro- and anti-inflammatory cytokines (IL-6, IL-8, IL-10, IL-1b, TNFa, and KC) secretion. Galarmin efficiently protects mice against lethal MRSA infection (100% of survival vs. 0% in the untreated group) when intramuscularly injected 24 h before infection and during the 1-h post-infection period at a concentration of 1 μg per mouse, while its higher concentrations (5 and 10 μg) were protective when injected in parallel to the infection process. The protective effect of galarmin was not due to a direct effect on MRSA, but should be attributed to an action on the host response to infection. Galarmin significantly increased and modulated the levels of IL-6, IL-8, IL-1b, IL-10, and KC in both peritoneal lavages and blood, leukocyte and platelet counts, lymphocytes percentage, serum IgM and IgG, and complement C3 and C4 components secretion. The experimental results allow concluding that galarmin is a powerful immunomodulatory and protective agent for the in vivo prophylaxis and treatment of MRSA-induced infection.

Comparative effectiveness of nafcillin or cefazolin versus vancomycin in methicillin-susceptible Staphylococcus aureus bacteremia

Background

The high prevalence of methicillin-resistant S. aureus (MRSA) has led clinicians to select antibiotics that have coverage against MRSA, usually vancomycin, for empiric therapy for suspected staphylococcal infections. Clinicians often continue vancomycin started empirically even when methicillin-susceptible S. aureus (MSSA) strains are identified by culture. However, vancomycin has been associated with poor outcomes such as nephrotoxicity, persistent bacteremia and treatment failure. The objective of this study was to compare the effectiveness of vancomycin versus the beta-lactam antibiotics nafcillin and cefazolin among patients with MSSA bacteremia. The outcome of interest for this study was 30-day in-hospital mortality.

Methods

This retrospective cohort study included all adult in-patients admitted to a tertiary-care facility between January 1, 2003 and June 30, 2007 who had a positive blood culture for MSSA and received nafcillin, cefazolin or vancomycin. Cox proportional hazard models were used to assess independent mortality hazards comparing nafcillin or cefazolin versus vancomycin. Similar methods were used to estimate the survival benefits of switching from vancomycin to nafcillin or cefazolin versus leaving patients on vancomycin. Each model included statistical adjustment using propensity scores which contained variables associated with an increased propensity to receive vancomycin.

Results

267 patients were included; 14% (38/267) received nafcillin or cefazolin, 51% (135/267) received both vancomycin and either nafcillin or cefazolin, and 35% (94/267) received vancomycin. Thirty (11%) died within 30 days. Those receiving nafcillin or cefazolin had 79% lower mortality hazards compared with those who received vancomycin alone (adjusted hazard ratio (HR): 0.21; 95% confidence interval (CI): 0.09, 0.47). Among the 122 patients who initially received vancomycin empirically, those who were switched to nafcillin or cefazolin (66/122) had 69% lower mortality hazards (adjusted HR: 0.31; 95% CI: 0.10, 0.95) compared to those who remained on vancomycin.

Conclusions

Receipt of nafcillin or cefazolin was protective against mortality compared to vancomycin even when therapy was altered after culture results identified MSSA. Convenience of vancomycin dosing may not outweigh the potential benefits of nafcillin or cefazolin in the treatment of MSSA bacteremia.

Use of antibacterial agents in renal failure

This article provides background information on the pharmacokinetics of antibacterial agents in patients who have normal and impaired renal function. Tables are provided to allow quick determination of appropriate dosages for varying degrees of renal failure. The use of serum levels; newer strategies for cefazolin, vancomycin and aminoglycoside dosing; methods of dialysis and associated antibiotics dosage adjustments, and antibiotic toxicity in renal failure are reviewed.

Vancomycin pharmacokinetics and pharmacodynamics during short daily hemodialysis

BACKGROUND AND OBJECTIVES

Short daily hemodialysis (SDHD) is an alternative to thrice-weekly HD because of its putative physiologic benefits. The purpose of this study was to investigate the effect of SDHD on the pharmacokinetics and pharmacodynamics of vancomycin.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Six noninfected adults who had anuria and were treated with SDHD were studied and received four dialysis sessions over 4 days. After completion of the first SDHD, each patient received vancomycin 15 mg/kg by intravenous infusion. Blood samples were collected over the ensuing 3 days during each subsequent inter- and intradialytic period. Pharmacokinetic parameters were determined. Serum concentration-time profiles were simulated for four vancomycin regimens with maintenance doses administered after every other SDHD. Area under the serum-concentration time curve (AUC) from 0 to 48 hours, 48 to 96 hours, and 96 to 144 hours were calculated, and Monte Carlo simulations were performed to determine the probability of target attainment at an AUC/minimum inhibitory concentration (MIC) ratio ≥800 for each 48-hour AUC at MICs ranging from 0.5 to 2.0 μg/ml.

RESULTS

Median (range) systemic clearance was 7.2 ml/min (5.3 to 10.0 ml/min), and dialytic clearance was 104 ml/min (94 to 106 ml/min). The steady-state volume of distribution was 55.4 L (34.8 to 77.2 L). At MICs ≤1 μg/ml, probability of target attainment was >90% for each 48-hour AUC when vancomycin was administered as a 20-mg/kg loading dose followed by 10 mg/kg after every other SDHD.

CONCLUSIONS

Vancomycin pharmacokinetic parameters in SDHD are consistent with data from thrice-weekly HD. A loading dose of 20 mg/kg followed by 10 mg/kg after every other SDHD provides adequate exposure for pathogens with MICs ≤1 μg/ml.

Clinical practice guidelines for the diagnosis and management of intravascular catheter-related infection: 2009 Update by the Infectious Diseases Society of America

These updated guidelines replace the previous management guidelines published in 2001. The guidelines are intended for use by health care providers who care for patients who either have these infections or may be at risk for them.

Treatment of dialysis catheter-related Enterococcus bacteremia with an antibiotic lock: a quality improvement report

BACKGROUND

Catheter-related bacteremia (CRB) is a frequent complication of tunneled dialysis catheters, and Enterococcus is a common infecting organism. CRB may be treated by instilling an antibiotic lock into the catheter lumen in conjunction with systemic antibiotics. The efficacy of this approach in Enterococcus bacteremia is unknown.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

64 catheter-dependent hemodialysis outpatients with vancomycin-sensitive Enterococcus bacteremia treated with a uniform antibiotic lock protocol. Clinical outcomes were tracked prospectively. QUALITY IMPROVEMENT PLANS: Patients received intravenous vancomycin for 3 weeks in conjunction with a vancomycin lock instilled into both catheter lumens after each dialysis session.

MEASURES

Treatment failure was defined as persistent fever 48 hours after initiation of antibiotic therapy or recurrent Enterococcus bacteremia within 90 days. A clinical cure was defined as fever resolution without recurrent bacteremia. Major infection-related complications within 6 months were documented.

RESULTS

Treatment failure occurred in 25 patients (39%) because of persistent fever in 10 and recurrent bacteremia in 15. Treatment success occurred in 39 patients (61%). A serious complication of Enterococcus CRB occurred in 4 of 64 patients (6%); endocarditis in 1 and osteomyelitis in 3. The frequency of serious complications was 16% (4 of 25 patients) in those with treatment failure compared with 0% (0 of 39 patients) in those with treatment success (P = 0.01).

LIMITATIONS

This was a single-center study. We did not measure serum vancomycin.

CONCLUSIONS

An antibiotic lock protocol permits catheter salvage in 61% of hemodialysis patients with Enterococcus CRB. Serious complications occur in 6% of patients and are more common in those with treatment failure.

Assessment of vancomycin use in chronic haemodialysis patients: room for improvement

BACKGROUND

Vancomycin is frequently prescribed for the management of infections in haemodialysis patients. We evaluated the appropriateness of vancomycin use in our chronic haemodialysis population.

METHODS

Charts of all chronic haemodialysis patients who received vancomycin between 1 March 2003 and 1 March 2004 were retrospectively reviewed. Indication was assessed according to the modified Hospital Infection Control Practices Advisory Committee guidelines for vancomycin prescription. The prescribed dosing regimens were evaluated.

RESULTS

A total of 163 courses of vancomycin in 105 patients were assessed. Of all courses, 88% were considered to be initially appropriate, but this decreased to 63% once culture and sensitivity results were available. Use of vancomycin for the management of beta-lactam-sensitive organisms accounted for the majority of inappropriate use. The most common vancomycin-dosing regimen prescribed was 500 mg intravenously at each haemodialysis session (51%); however, considerable variability was observed.

CONCLUSIONS

Although the initial indication for vancomycin use was generally appropriate, inappropriate continuation of this antibiotic, failure to obtain proper cultures to guide therapy and potentially subtherapeutic dosing regimens were some of the challenges identified. Centres providing chronic haemodialysis should take steps to optimize vancomycin prescription to improve clinical outcomes and reduce the risk of antimicrobial resistance.

Pharmacokinetic and Pharmacodynamic Aspects of Antibiotic Use in High-Risk Populations

The study of pharmacokinetics includes the absorption, distribution, metabolism, and elimination of drugs. The pharmacologic effect that a medication has on the body is known as pharmacodynamics. With antimicrobials, pharmacokinetic and pharmacodynamic parameters become especially important because of the association between host drug concentrations, microorganism eradication, and resistance. This article focuses on the pharmacokinetic changes that can occur with antimicrobials when they are used in patients at high risk of infections and how they influence pharmacodynamic effects. The populations described here include patients with obesity and diabetes mellitus, renal or hepatic failure, chronic lung disease, severe burns, and long-term prosthetic devices and the elderly.

Treatment of dialysis catheter-related Staphylococcus aureus bacteremia with an antibiotic lock: a quality improvement report

BACKGROUND

Dialysis catheter-related bacteremia is often treated successfully by instilling an antibiotic-heparin solution into the catheter lumen (an antibiotic lock) in conjunction with systemic antibiotic therapy without removal of the catheter. The efficacy of this therapy is uncertain in Staphylococcus aureus bacteremia.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

113 catheter-dependent hemodialysis outpatients with S aureus catheter-related bacteremia treated with a standardized antibiotic lock protocol. Data for all patients with catheter-related bacteremia are recorded in a prospective database.

QUALITY IMPROVEMENT PLAN

In conjunction with systemic antibiotic therapy (vancomycin for methicillin-resistant S aureus or cefazolin for methicillin-sensitive S aureus), an antibiotic lock was instilled into each catheter lumen after each dialysis session for 3 weeks.

MEASURES

Treatment failure is defined as persistent fever after 48 hours of antibiotic therapy or recurrent S aureus bacteremia within 90 days. Clinical cure is defined as resolution of fever and no recurrence of bacteremia. Major infection-related complications within 6 months were documented.

RESULTS

The catheter could not be salvaged in 67 patients (59%) because of persistent fever in 40 patients and recurrent bacteremia in 27 patients. A clinical cure was achieved in 46 patients (41%). A serious complication of catheter-related bacteremia occurred in 9.7% of all patients (11 of 113 patients). Serious complications were observed in 25% of patients (10 of 40 patients) with persistent fever, but only 1.4% of all other patients (1 of 73 patients; P < 0.0001).

LIMITATIONS

This was a single-center study. Serum antibiotic levels were not measured.

CONCLUSIONS

Routine antibiotic lock therapy is not appropriate for patients with S aureus catheter-related bacteremia. Serious complications occur primarily in patients with persistent fever.

Current management of vascular access

Optimizing vascular access outcomes remains an ongoing challenge for clinical nephrologists. All other things being equal, fistulas are preferred over grafts, and grafts are preferred over catheters. Mature fistulas have better longevity and require fewer interventions, as compared with mature grafts. The major hurdle to increasing fistula use is the high rate of failure to mature of newly created fistulas. There is a desperate need for enhanced understanding of the mechanisms of failure to mature and the optimal type and timing of interventions to promote maturity. Grafts are prone to frequent stenosis and thrombosis. Surveillance for graft stenosis with preemptive angioplasty may reduce graft thrombosis, but recent randomized clinical trials have questioned the efficacy of this approach. Graft stenosis results from aggressive neointimal hyperplasia, and pharmacologic approaches to slowing this process are being investigated in clinical trials. Catheters are prone to frequent thrombosis and infection. The optimal management of catheter-related bacteremia is a subject of ongoing debate. Prophylaxis of catheter-related bacteremia continues to generate important clinical research. Close collaboration among nephrologists, surgeons, radiologists, and the dialysis staff is required to optimize vascular access outcomes and can be expedited by having a dedicated access coordinator to streamline the process. The goal of this review is to provide an update on the current status of vascular access management.