According to the 2020 guidelines for the therapeutic monitoring of vancomycin for serious methicillin-resistant Staphylococcus aureus (MRSA) infections from the American Society of Health-System Pharmacists (ASHP), the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Diseases Society (PIDS), and the Society of Infectious Diseases Pharmacists (SIDP), monitoring serum concentration is essential for guiding vancomycin dosing in patients receiving intermittent hemodialysis (HD), particularly as modern high-permeability dialyzers significantly clear the drug, necessitating more frequent dosing than historical recommendations. Although outcome studies validating the goal area under the curve (AUC) AUC24h of 400 to 600 mg*h/L, used in other populations, are lacking for HD patients, this target is currently recommended. Due to practical limitations in HD patients, monitoring is most often based on predialysis serum concentrations. To ensure the AUC target of 400 to 600 mg*h/L is achieved, maintaining predialysis concentrations between 15 and 20 mg/L is recommended. Critically, blood samples for monitoring should not be drawn during or for at least two hours after an HD session, as these samples inaccurately reflect the true body load and could lead to erroneous dosing decisions. For a guideline-recommended dosing summary of vancomycin in HD patients, refer to Table 1. [1]
A 2021 editorial review discusses the newly revised vancomycin dosing guidelines for patients with End-Stage Kidney Disease (ESKD) undergoing hemodialysis. These guidelines address the complexities surrounding vancomycin therapy in such patients, particularly due to the prevalence of MRSA infections. The guidelines shift from the trough-only therapeutic drug monitoring (TDM) approach recommended in the 2009 consensus to an area under the curve/minimum inhibitory concentration (AUC/MIC) ratio method. The updated protocol recommends a target AUC/MIC ratio of 400-600, aiming to improve pharmacodynamic efficacy while minimizing the risk of vancomycin-associated acute kidney injury (AKI). The recommendations emphasize the adoption of AUC-based TDM, ideally through pharmacokinetic (PK) modeling software such as Bayesian forecasting programs, which allows individualized dosing regimens. The editorial highlights the numerous logistical challenges in implementing these recommendations, particularly in outpatient hemodialysis settings where blood sampling timing, dosing adjustments, and vancomycin infusion times can complicate treatment. Although a weight-based initial dosing regimen and a predialysis serum concentration target of 15-20 mg/L are suggested, the editorial acknowledges significant inter-individual pharmacokinetic variability and the lack of comprehensive outcomes data for ESKD patients. For a summary of vancomycin dosing and monitoring recommendations for patients receiving hemodialysis, refer to Table 2. [2]
The 2017 IDSA Clinical Practice Guidelines for Healthcare-Associated Ventriculitis and Meningitis synthesized data through a systematic review involving a multidisciplinary panel of experts from infectious diseases, neurology, and neurosurgery specialties. Empiric treatment with vancomycin plus an anti-pseudomonal beta-lactam (e.g., cefepime or meropenem) was advised, with adjustments based on local susceptibility patterns and the presence of antimicrobial-resistant organisms. The panel states that in seriously ill adult patients with healthcare-associated ventriculitis and meningitis, the vancomycin trough concentration should be maintained at 15-20 mcg/mL in those who receive intermittent bolus administration. [3]
Further guidance from the ASHP/IDSA/PIDS/SIDP consensus guidelines on therapeutic monitoring of vancomycin for serious MRSA infections provide recommendations reflective of recent data in regards to specific dosing and monitoring of vancomycin, which was not reflected in the original consensus guidelines published in 2009. Trough-only monitoring, with a target of 15 to 20 mg/L, is no longer recommended based on efficacy and nephrotoxicity data in patients with serious infections due to MRSA. Given the narrow vancomycin AUC range for therapeutic effect and minimal AKI risk, it is now recommended that the most accurate and optimal way to manage vancomycin dosing is through AUC-guided dosing and monitoring. [1], [2], [3], [4]
To accomplish this, the guidelines recommend two approaches, one of which relies on the collection of 2 concentrations (obtained near steady-state, postdistributional peak concentration [Cmax] at 1 to 2 hours after infusion and trough concentration [Cmin] at the end of the dosing interval), preferably but not required during the same dosing interval (if possible) and utilizing first order PK equations to estimate the AUC. The preferred approach to monitor AUC, however, involves the use of Bayesian software programs, embedded with a PK model based on richly sampled vancomycin data as the Bayesian prior, to optimize the delivery of vancomycin based on the collection of 1 or 2 vancomycin concentrations, with at least 1 trough. With this approach, it is preferred to obtain 2 PK samples (i.e., at 1 to 2 hours post-infusion and at the end of the dosing interval) to estimate the AUC. A trough concentration alone may be sufficient to estimate the AUC with the Bayesian approach in some patients, but more data are needed across different patient populations to confirm the viability of using trough-only data. Notably, the guidelines state that there is an absence of clinical outcomes data specific to osteomyelitis or meningitis that establishes the efficacy of AUC/MIC-guided vancomycin dosing in these settings. [1]
For patients with suspected or definitive serious MRSA infections, an individualized target of AUC over 24 hours to MIC determined by broth microdilution (AUC/MICBMD) ratio of 400 to 600 (assuming a vancomycin MICBMD of 1 mg/L) should be advocated to achieve clinical efficacy while improving patient safety. Doses of 15 to 20 mg/kg (based on actual body weight) administered every 8 to 12 hours as an intermittent infusion are recommended for most patients with normal renal function when assuming a MICBMD of 1 mg/L. In patients with normal renal function, such doses may not achieve the therapeutic AUC/MIC target when the MIC is 2 mg/L. It should be noted that there is insufficient evidence to provide recommendations on whether trough-only or AUC-guided vancomycin monitoring should be used among patients with noninvasive MRSA or other infections. [1]
A 2021 review discusses the most substantial changes in the revised vancomycin consensus guidelines including the recommendation to transition from trough-only to AUC-guided dosing and monitoring for patients receiving vancomycin for “suspected or definitive serious invasive MRSA infections” and to maintain daily AUCs between 400 and 600 mg x hr/L. In general, the basis for the shift from troughs of 15-20 mg/L to AUC-guided dosing and monitoring was to minimize vancomycin-associated acute kidney injury (VA-AKI) while maintaining similar effectiveness. Available data indicate that VA-AKI increases as a function of the intensity and duration of vancomycin exposure. Despite being widely utilized in practice, data demonstrating the clinical benefits of maintaining higher troughs are lacking. The 2009 consensus guidelines recommend maintaining troughs between 15 and 20 to simplify dosing and monitoring, but there were a lack of high-quality efficacy and safety data to support this recommendation at the time, and it was solely based on the fact that a trough within this range will consistently ensure a daily AUC greater than 400. Despite this, the 2009 consensus guidelines did not account for the fact that a wide range of upper AUC values can occur with a given trough value. When examining the relationship between day 2 trough and AUC among simulated subjects with troughs between 15 and 20, 48% of patients will have daily AUCs greater than 600, which could result in a higher risk for VA-AKI. [1, 4, 5]
A 2014 prospective study evaluated the cerebrospinal fluid (CSF) penetration of vancomycin in adults with acute community-acquired meningitis. This investigation enrolled 27 adult patients (mean age 39.4 ± 14.7 years) who presented with clinical and CSF findings consistent with acute meningitis. All participants received a loading dose of vancomycin at 15 mg/kg followed by a maintenance regimen of 30 mg/kg/day in two divided intravenous doses, administered alongside ceftriaxone (2 g IV twice daily). Notably, no corticosteroids were administered, thereby eliminating a known confounder on meningeal permeability. High-performance liquid chromatography (HPLC) was utilized for quantifying vancomycin concentrations in both serum and CSF, with sampling performed 15–30 minutes prior to the fourth vancomycin dose and again during days 8 to 10 of treatment in 14 patients. Initial trough vancomycin concentrations measured in serum and CSF were 13.82 ± 1.28 mg/L and 11.2 ± 1.41 mg/L, respectively, yielding a CSF-to-serum ratio of 0.811 ± 0.082. A positive linear correlation between serum and CSF levels was identified (r = 0.60, p = 0.004). Repeat measurements taken on days 8 to 10 demonstrated consistent trough levels (serum: 13.32 ± 1.02 mg/L; CSF: 10.64 ± 1.21 mg/L; CSF/serum ratio: 0.79 ± 0.063), with no statistically significant decline over time, despite the resolution of meningeal inflammation markers. Notably, changes in CSF leukocyte count, protein, and glucose did not correlate with vancomycin concentrations, and serum creatinine remained stable throughout the treatment period. These findings underscore the sustained and clinically meaningful CSF penetration of vancomycin in the setting of acute meningeal inflammation, suggesting reliable therapeutic exposure without the necessity of intrathecal administration. [6]
A 2019 retrospective, observational analysis evaluated vancomycin pharmacokinetic parameters using two-level monitoring in 34 hospitalized adult patients treated for presumed or confirmed invasive staphylococcal infections. Conducted across two acute care hospitals within the Aurora Health Care system in Wisconsin, the investigation focused on correlating vancomycin serum trough (Cmin) concentrations to 24-hour area under the concentration-time curve to minimum inhibitory concentration ratio (AUC/MIC), aiming to inform institutional vancomycin dosing protocols. Pharmacist-managed vancomycin therapy utilized a non-Bayesian, equation-based approach. Two steady-state levels were drawn per patient: one approximately two hours post-infusion and a trough obtained 30 minutes prior to the subsequent dose. Among 36 paired samples from 34 patients, most (91.2%) of whom were admitted to intensive care units, and 85.3% of patients were prescribed vancomycin for bacteremia, pneumonia, or endocarditis. The mean vancomycin Cmin was 16.6 ± 6.1 mg/L, and the mean AUC/MIC was 588 ± 156 mg*h/L. Notably, 91.2% of patients achieved a 24-hour AUC/MIC ≥ 400 mg*h/L, and among those with a Cmin > 9 mg/L, 100% reached the AUC/MIC threshold of 400 mg*h/L and 93.9% exceeded 500 mg*h/L. A strong linear correlation was observed between vancomycin Cmin and AUC24 (R² = 0.731; P <0.001). Subgroup analysis revealed a weaker correlation in patients with creatinine clearance ≥ 120 mL/min (R² = 0.2579), weight <60 kg (R² = 0.1767), or weight >90 kg (R² = 0.0687). Furthermore, in 63.1% of patients who continued vancomycin therapy after AUC determination, dose reductions were implemented relative to institutional nomogram-based dosing. These findings underscore the potential for overexposure when targeting trough concentrations of 15-20 mg/L and suggest a lower trough range may ensure therapeutic AUC while minimizing nephrotoxicity risk. [7]
A 2022 systematic review synthesized findings from 19 clinical investigations, comprising a total of 482 patients, to evaluate the efficacy, safety, and pharmacokinetics of both intravenous (IV) and intraventricular (IVT) vancomycin in the treatment of central nervous system (CNS) infections, including meningitis, ventriculitis, and CNS device–associated infections. The review highlighted that the optimal dosing regimens still remain unclear, and therapeutic drug monitoring is often conducted to ensure adequate cerebrospinal fluid (CSF) concentrations. Across the included studies, IV vancomycin doses ranged from 1,000 to 3,000 mg/day, with dosing frequencies commonly at 15 mg/kg every 6 hours. IVT vancomycin doses spanned from 2 to 20 mg/day, typically administered once daily. Therapeutic drug monitoring (TDM) was conducted in 14 of the reviewed studies, although no consistent relationship was found between CSF vancomycin concentrations and therapeutic efficacy or toxicity. Pharmacokinetic data revealed wide variability in CSF concentrations for both IV (0.06–22.3 mg/L) and IVT (2.5–292.9 mg/L) administration routes. Notably, CSF-to-serum ratios varied significantly, ranging from 0.00 to 0.81, with some studies suggesting enhanced penetration in the presence of meningeal inflammation. No serious adverse effects, including nephrotoxicity, were attributed to either IV or IVT vancomycin administration. Clinical outcomes indicated favorable responses in most cases, with CSF sterilization achieved in 88.4% of patients treated with IVT vancomycin alone. Despite observed efficacy and an acceptable safety profile, the review highlighted the need for high-quality clinical trials to further delineate optimal dosing strategies and characterize CNS pharmacokinetics to inform therapeutic decision-making in CNS infections. [8]
A 2024 case report described the clinical management of MRSA meningitis using vancomycin with a high AUC/MIC strategy. A 61-year-old woman who underwent ventriculoperitoneal (VP) shunt placement following subarachnoid hemorrhage developed healthcare-associated meningitis due to shunt infection. Gram-positive cocci were identified by CSF Gram stain, and MRSA was confirmed by molecular testing. Targeted therapy with IV vancomycin at 25 mg/kg every 12 hours was initiated after initial treatment with piperacillin-tazobactam. Serial therapeutic drug monitoring was performed utilizing Bayesian software to estimate pharmacokinetic parameters from paired peak and trough levels. On postoperative day (POD) 24, an AUC/MIC of 515 was achieved, but CSF cultures remained positive. Escalation of vancomycin dosing to 30 mg/kg every 8 hours increased the AUC/MIC to 610 by POD 28, with a concurrent increase in trough to 18.6 μg/mL. CSF cultures turned negative by POD 30, and an AUC/MIC of 700 was recorded. Therapeutic efficacy coincided with higher vancomycin AUC exposure, suggesting a potential benefit of targeting an AUC/MIC at or near the upper boundary of the recommended therapeutic window (400–600) in CNS infections. The vancomycin CSF-to-serum ratio averaged approximately 41%, with CSF concentrations of 5.4 μg/mL at MRSA-positive and 6.2 μg/mL at MRSA-negative culture points. Despite achieving early bloodstream clearance, CSF sterilization lagged until AUC/MIC exceeded 600, supporting the notion that the conventional target of ≥400 may be insufficient for MRSA meningitis. Notably, the patient experienced no vancomycin-associated nephrotoxicity during therapy, although a non-serious drug eruption prompted treatment discontinuation on POD 47. These findings underscore that AUC-guided dosing offers enhanced precision and safety over trough-only strategies, particularly in infections with limited drug penetration, such as CNS involvement. [9]