Should the trough concentration of vancomycin be abandoned in therapeutic drug monitoring? A multicentre, retrospective study of critically ill patients without any form of dialysis.

BACKGROUND: There are conflicts in guideline recommendations about the value and range of vancomycin trough concentration during therapeutic drug monitoring (TDM). This multicentre, retrospective study was conducted to explore the usefulness of trough concentration in specific patients who were critically ill and without any form of dialysis. METHODS: Patient information from five centres was retrospectively collected and the 24-hour area under the curve (AUC) was estimated by a Bayesian method. Patients were categorised into four groups according to trough concentration: < 10, 10-15, 15-20 and > 20 mg/L, and the corresponding AUC was analysed. A multivariable logistic regression model was used to investigate the relationship between trough concentration and AUC. RESULTS: Overall, 645 trough concentrations available from 416 patients were included in this study. The results indicated that the AUC was always < 400 mg/L∙h or > 600 mg/L∙h in the < 10 or > 20 mg/L groups, whereas the ratios of vancomycin AUC target attainment (400-600 mg/L∙h) were 48.8% and 92.3% in the 10-15 mg/L and 15-20 mg/L groups, respectively. Augmented renal clearance, low daily dose and non-q12h administration were found to be independent risk factors associated with AUC target non-attainment for patients with trough concentrations of 10-15 mg/L. CONCLUSION: Vancomycin trough concentration is a good marker of AUC for critically ill adults without any form of dialysis. However, AUC-guided TDM may be needed for patients with trough concentrations of 10-15 mg/L, especially for those with risk factors.

Individualized Vancomycin Dosing with Therapeutic Drug Monitoring and Pharmacokinetic Consultation Service: A Large-Scale Retrospective Observational Study.

BACKGROUND: To date, outcome data with a large sample size and data regarding the clinical outcomes of pharmacokinetic-guided (PK) dosing of vancomycin are limited. AIM: We evaluated the pharmacokinetic and clinical outcomes of a PK-guided dosing advisory program, pharmacokinetic consultation service (PKCS), in vancomycin treatment. METHODS: We investigated vancomycin therapeutic drug monitoring (TDM) and PKCS use through a retrospective review of patients who had serum vancomycin trough concentration data from October 2017 to November 2018. Among these patients, we selected non-critically ill adult patients satisfying our selection criteria to evaluate the effect of PKCS. Target trough attainment rate, time to target attainment, vancomycin-induced nephrotoxicity (VIN), vancomycin treatment failure rate, and duration of vancomycin therapy were compared between patients whose dosing was adjusted according to PKCS (PKCS group), and those whose dose was adjusted at the discretion of the attending physician (non-PKCS group). RESULTS: A total of 280 patients met the selection criteria for the VIN analysis (PKCS, n=134; non-PKCS, n=146). The incidence of VIN was similar between the two groups (PKCS, n=5; non-PKCS, n=5); however, the target attainment rate was higher in the PKCS group (75% vs 60%, P = 0.012). The time to target attainment was similar between the two groups. Further exclusions yielded 112 patients for the clinical outcome evaluation (PKCS, n=51; non-PKCS, n=61). The treatment failure rate was similar, and the duration of vancomycin therapy was longer in the PKCS group (12 vs 8 days, P = 0.008). CONCLUSION: In non-critically ill patients, an increase in target trough achieved by PKCS did not lead to decreased vancomycin treatment failures, shorter vancomycin treatment, or decreased nephrotoxicity in vancomycin treatment. Considering the excessive amount of effort currently put into vancomycin dosing and monitoring, more selective criteria for individualized pharmacokinetic-guided dosing needs to be applied.

Optimal trough concentration of teicoplanin for the treatment of methicillin-resistant Staphylococcus aureus infection: A systematic review and meta-analysis.

WHAT IS KNOWN AND OBJECTIVE: It has been recommended that the trough concentration (Cmin ) of teicoplanin should be maintained at ≥20 µg/ml for difficult-to-treat complicated infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Conversely, Cmin of teicoplanin of at least 10 µg/ml is required for non-complicated MRSA infections. Considering the low incidence of nephrotoxicity for teicoplanin, Cmin  = 15-30 µg/ml has been suggested for most MRSA infections. Thus, we assessed the clinical efficacy and adverse effects of teicoplanin at this target Cmin . METHODS: We searched electronic databases (PubMed, Cochrane Central Register of Controlled Trials and Ichushi-Web) to identify eligible studies. Studies were included if they provided the incidence of treatment success, mortality in patients with MRSA infection, and/or hepatotoxicity and nephrotoxicity according to the Cmin range. RESULTS AND DISCUSSION: Four trials assessing clinical success (n = 299) and three studies assessing adverse effects (n = 546) were included. Cmin  = 15-30 µg/ml significantly increased the probability of treatment success compared with Cmin  < 15 µg/ml (odds ratio [OR] = 2.68, 95% confidence interval [CI] = 1.14-6.32, p = 0.02). The all-cause mortality rate did not differ between the groups (OR = 0.46, 95% CI = 0.13-1.61, p = 0.22). Cmin  = 15-30 µg/ml did not increase the risks of nephrotoxicity (OR = 0.91, 95% CI = 0.49-1.69, p = 0.76) or hepatotoxicity (OR = 0.67, 95% CI = 0.18-2.44, p = 0.54). WHAT IS NEW AND CONCLUSION: Teicoplanin therapy using a Cmin target of 15-30 µg/ml is likely to be associated with better clinical responses than Cmin  < 15 µg/ml without increasing the risk of adverse effects.

Association between single trough-based area under the curve estimation of vancomycin and treatment outcome among methicillin-resistant Staphylococcus aureus bacteremia patients.

BACKGROUND: Failure of antibiotic treatment increases mortality of critically ill patients. This study investigated the association between the treatment resolution of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and vancomycin pharmacokinetic variables. METHODS: A total of 28 critically ill patients were included in this study. All data were collected from medical, microbiology and pharmacokinetic records. The clinical response was evaluated on the basis of clinical and microbiological parameters. The 24-h area under the curve (AUC_0-24) was estimated from a single trough level using established equations. RESULTS: Out of the 28 patients, 46% were classified as responders to vancomycin treatment. The trough vancomycin concentration did not differ between the responders and non-responders (15.02 ± 6.16 and 14.83 ± 4.80 µg mL-1; P = 0.929). High vancomycin minimum inhibitory concentration (MIC) was observed among the non-responders (P = 0.007). The ratio between vancomycin trough concentration and vancomycin MIC was significantly lower in the non-responder group (8.76 ± 3.43 vs. 12.29 ± 4.85 µg mL-1; P = 0.034). The mean ratio of estimated AUC_0-24 and vancomycin MIC was 313.78 ± 117.17 µg h mL-1 in the non-responder group and 464.44 ± 139.06 µg h mL-1 in the responder group (P = 0.004). AUC_0-24/MIC of ≥ 400 µg h mL-1 was documented for 77% of the responders and 27% of the non-responders (c2 = 7.03; P = 0.008). CONCLUSIONS: Ratio of trough concentration/MIC and AUC_0-24/MIC of vancomycin are better predictors for MRSA treatment outcomes than trough vancomycin concentration or AUC_0-24 alone. The single trough-based estimated AUC may be sufficient for the monitoring of treatment response with vancomycin.

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

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

A Quasi-Experiment To Study the Impact of Vancomycin Area under the Concentration-Time Curve-Guided Dosing on Vancomycin-Associated Nephrotoxicity.

Evidence suggests that maintenance of vancomycin trough concentrations at between 15 and 20 mg/liter, as currently recommended, is frequently unnecessary to achieve the daily area under the concentration-time curve (AUC24) target of ≥400 mg · h/liter. Many patients with trough concentrations in this range have AUC24 values in excess of the therapeutic threshold and within the exposure range associated with nephrotoxicity. On the basis of this, the Detroit Medical Center switched from trough concentration-guided dosing to AUC-guided dosing to minimize potentially unnecessary vancomycin exposure. The primary objective of this analysis was to assess the impact of this intervention on vancomycin-associated nephrotoxicity in a single-center, retrospective quasi-experiment of hospitalized adult patients receiving intravenous vancomycin from 2014 to 2015. The primary analysis compared the incidence of nephrotoxicity between patients monitored by assessment of the AUC24 and those monitored by assessment of the trough concentration. Multivariable logistic and Cox proportional hazards regression examined the independent association between the monitoring strategy and nephrotoxicity. Secondary analysis compared vancomycin exposures (total daily dose, AUC, and trough concentrations) between monitoring strategies. Overall, 1,280 patients were included in the analysis. After adjusting for severity of illness, comorbidity, duration of vancomycin therapy, and concomitant receipt of nephrotoxins, AUC-guided dosing was independently associated with lower nephrotoxicity by both logistic regression (odds ratio, 0.52; 95% confidence interval [CI], 0.34 to 0.80; P = 0.003) and Cox proportional hazards regression (hazard ratio, 0.53; 95% CI, 0.35 to 0.78; P = 0.002). AUC-guided dosing was associated with lower total daily vancomycin doses, AUC values, and trough concentrations. Vancomycin AUC-guided dosing was associated with reduced nephrotoxicity, which appeared to be a result of reduced vancomycin exposure.

Vancomycin AUC24 /MIC Ratio in Patients with Methicillin-Resistant Staphylococcus aureus Pneumonia.

BACKGROUND: Vancomycin is the treatment of choice for serious methicillin-resistant Staphylococcus aureus (MRSA) infections. The area under the concentration-time curve from 0 to 24 hr (AUC24 )/minimum inhibitory concentration (MIC) ratio was recently introduced as a parameter for assessing clinical outcome by S. aureus. This study was purposed to apply the vancomycin AUC24 /MIC in patients with MRSA pneumonia. METHODS: Forty-seven patients with confirmed lower respiratory infection caused by MRSA during 2011 were enrolled. All patients were treated with vancomycin. Clinical characteristics and laboratory data were collected. AUC24 /MIC values were calculated as previously reported and patients were divided into two groups based on the bacteriologic response, which was eradicated or not, and an AUC24 /MIC value (above or below 400). RESULTS: MRSA infections were eradicated in 39 patients but 8 patients had persistent MSRA infection in the following cultures. The mean AUC24 /MIC values and vancomycin concentrations were not statistically different between patients with and without MRSA eradication. All 13 patients with a vancomycin MIC of 2 mg/L had an AUC24 /MIC below 400. CONCLUSION: AUC24 /MIC might not be a reliable indicator for assessing treatment response of vancomycin in MRSA pneumonia. Relationship between vancomycin AUC24 /MIC and therapeutic outcome needs to undergo further studies, including sufficiently large sample size.

Vancomycin serum trough concentration vs. clinical outcome in patients with gram-positive infection: a retrospective analysis.

WHAT IS KNOWN AND OBJECTIVE: Vancomycin is still the first-line treatment for resistant gram-positive infections, particularly for methicillin-resistant Staphylococcus aureus (MRSA) infections. The vancomycin treatment guideline is based on the association between vancomycin trough concentration and clinical outcome. We here present a retrospective analysis of whether the trough level of vancomycin is associated with clinical outcome in Chinese patients with gram-positive infections. METHODS: Clinical data were collected retrospectively from patients under vancomycin therapeutic drug monitoring in Huashan Hospital from March 2004 to September 2014. RESULTS AND DISCUSSION: A total of 148 inpatients with gram-positive infection were identified and data on their corresponding vancomycin serum trough concentration retrieved. A total of 113 strains of gram-positive bacteria were isolated from 111 patients, including 90 strains of MRSA. Vancomycin was used for 11 to 13 days on average. The overall bacterial eradication rate was 67·3% (76/113), including 61·1% (55/90) for MRSA and 91·3% (21/23) for Enterococcus. Multivariate logistic model analysis showed that vancomycin trough concentration was not associated with clinical outcome (OR: 1·0; 95% CI: 0·92, 1·08, P = 0·9613). The incidence of adverse drug reactions was low and not related to vancomycin trough concentration. WHAT IS NEW AND CONCLUSION: This retrospective analysis failed to demonstrate an association between vancomycin trough concentration and the clinical and microbiological response. Prospective controlled studies are necessary to further establish the need for the higher trough concentrations normally cited for clinical efficacy.