Relationship between Pharmacokinetic/Pharmacodynamic Target Attainment and Microbiological Outcome in Critically Ill COVID-19 Patients with Documented Gram-Negative Superinfections Treated with TDM-Guided Continuous-Infusion Meropenem

Spider chart, greenness and whiteness assessment of experimentally designed multivariate models for simultaneous determination of three drugs used as a combinatory antibiotic regimen in critical care units: Comparative study

In this study, five earth-friendly spectrophotometric methods using multivariate techniques were developed to analyze levofloxacin, linezolid, and meropenem, which are utilized in critical care units as combination therapies. These techniques were used to determine the mentioned medications in laboratory-prepared mixtures, pharmaceutical products and spiked human plasma that had not been separated before handling. These methods were named classical least squares (CLS), principal component regression (PCR), partial least squares (PLS), genetic algorithm partial least squares (GA-PLS), and artificial neural network (ANN). The methods used a five-level, three-factor experimental design to make different concentrations of the antibiotics mentioned (based on how much of them are found in the plasma of critical care patients and their linearity ranges). The approaches used for levofloxacin, linezolid, and meropenem were in the ranges of 3-15, 8-20, and 5-25 µg/mL, respectively. Several analytical tools were used to test the proposed methods' performance. These included the root mean square error of prediction, the root mean square error of cross-validation, percentage recoveries, standard deviations, and correlation coefficients. The outcome was highly satisfactory. The study found that the root mean square errors of prediction for levofloxacin were 0.090, 0.079, 0.065, 0.027, and 0.001 for the CLS, PCR, PLS, GA-PLS, and ANN models, respectively. The corresponding values for linezolid were 0.127, 0.122, 0.108, 0.05, and 0.114, respectively. For meropenem, the values were 0.230, 0.222, 0.179, 0.097, and 0.099 for the same models, respectively. These results indicate that the developed models were highly accurate and precise. This study compared the efficiency of artificial neural networks and classical chemometric models in enhancing spectral data selectivity for quickly identifying three antimicrobials. The results from these five models were subjected to statistical analysis and compared with each other and with the previously published ones. Finally, the whiteness of the methods was assessed by the recently published white analytical chemistry (WAC) RGB 12, and the greenness of the proposed methods was assessed using AGREE, GAPI, NEMI, Raynie and Driver, and eco-scale, which showed that the suggested approaches had the least negative environmental impact. Furthermore, to demonstrate solvent sustainability, a greenness index using a spider chart methodology was employed.

How to use meropenem in pediatric patients undergoing CKRT? Integrated meropenem pharmacokinetic model for critically ill children

Standard dosing could fail to achieve adequate systemic concentrations in ICU children or may lead to toxicity in children with acute kidney injury. The population pharmacokinetic analysis was used to simultaneously analyze all available data (plasma, prefilter, postfilter, effluent, and urine concentrations) and provide the pharmacokinetic characteristics of meropenem. The probability of target fT > MIC attainment, avoiding toxic levels, during the entire dosing interval was estimated by simulation of different intermittent and continuous infusions in the studied population. A total of 16 critically ill children treated with meropenem were included, with 7 of them undergoing continuous kidney replacement therapy (CKRT). Only 33% of children without CKRT achieved 90% of the time when the free drug concentration exceeded the minimum inhibitory concentration (%fT > MIC) for an MIC of 2 mg/L. In dose simulations, only continuous infusions (60-120 mg/kg in a 24-h infusion) reached the objective in patients <30 kg. In patients undergoing CKRT, the currently used schedule (40 mg/kg/12 h from day 2 in a short infusion of 30 min) was clearly insufficient in patients <30 kg. Keeping the dose to 40 mg/kg q8h without applying renal adjustment and extended infusions (40 mg/kg in 3- or 4-h infusion every 12 h) was sufficient to reach 90% fT > MIC (>2 mg/L) in patients >10 kg. In patients <10 kg, only continuous infusions reached the objective. In patients >30 kg, 60 mg/kg in a 24-h infusion is sufficient and avoids toxicity. This population model could help with an individualized dosing approach that needs to be adopted in critically ill pediatric patients. Critically ill patients subjected to or not to CKRT may benefit from the administration of meropenem in an extended or continuous infusion.

Could an optimized joint pharmacokinetic/pharmacodynamic target attainment of continuous infusion ceftazidime-avibactam be a way to avoid the need for combo therapy in the targeted treatment of deep-seated DTR Gram-negative infections?

The objective of this study was to assess the relationship between joint pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) ceftazidime-avibactam and the microbiological outcome of documented difficult-to-treat resistant (DTR) Gram-negative infections. A 2-year retrospective cohort study was performed in patients receiving CI ceftazidime-avibactam mono- or combo therapy for documented DTR Gram-negative infections and undergoing therapeutic drug monitoring of both ceftazidime and avibactam. The free fractions of steady-state concentrations (fCss) of ceftazidime and avibactam were calculated. The joint PK/PD target was considered optimal when both the fCss/MIC ratio for ceftazidime ≥4 (equivalent to 100% fT>4xMIC) and the fCss/CT ratio for avibactam >1 (equivalent to 100% fT >CT of 4.0 mg/L) were simultaneously achieved (quasi-optimal if only one of the two and suboptimal if neither of the two was achieved). Multivariate logistic regression analysis was applied for testing potential variables associated with microbiological failure. Fifty-eight patients were treated with CI ceftazidime-avibactam mono- (36) or combo therapy (22) for documented DTR Gram-negative infections [74.2% for primary or secondary bloodstream infections (BSIs)]. Combo therapy was administered more frequently to intensive care unit (ICU) patients (P = 0.023) or for pneumonia (P = 0.001) and less frequently for intra-abdominal infections and BSIs (P = 0.04). Microbiological failure occurred in five cases (8.6%, three in mono- and two in combo therapy). In the multivariate analysis, the suboptimal/quasi-optimal joint PK/PD target emerged as the only independent predictor of microbiological failure (odds ratio [OR] 11.11; 95% confidence interval [CI] 1.31-93.98; P = 0.023), whereas monotherapy was not (P = 0.99). Optimized joint PK/PD target attainment of CI ceftazidime-avibactam monotherapy could represent a way forward for allowing microbiological eradication of DTR Gram-negative infections and could render unnecessary combo therapy.

Role of a Real-Time TDM-Based Expert Clinical Pharmacological Advice Program in Optimizing the Early Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Beta-Lactams among Orthotopic Liver Transplant Recipients with Documented or Suspected Gram-Negative Infections

(1) Objectives: To describe the attainment of optimal pharmacokinetic/pharmacodynamic (PK/PD) targets in orthotopic liver transplant (OLT) recipients treated with continuous infusion (CI) beta-lactams optimized using a real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program during the early post-surgical period. (2) Methods: OLT recipients admitted to the post-transplant intensive care unit over the period of July 2021-September 2023, receiving empirical or targeted therapy with CI meropenem, piperacillin-tazobactam, meropenem-vaborbactam, or ceftazidime-avibactam optimized using a real-time TDM-guided ECPA program, were retrospectively retrieved. Steady-state beta-lactam (BL) and/or beta-lactamase inhibitor (BLI) plasma concentrations (Css) were measured, and the Css/MIC ratio was selected as the best PK/PD target for beta-lactam efficacy. The PK/PD target of meropenem was defined as being optimal when attaining a fCss/MIC ratio > 4. The joint PK/PD target of the BL/BLI combinations (namely piperacillin-tazobactam, ceftazidime-avibactam, and meropenem-vaborbactam) was defined as being optimal when the fCss/MIC ratio > 4 of the BL and the fCss/target concentration (CT) ratio > 1 of tazobactam or avibactam, or the fAUC/CT ratio > 24 of vaborbactam were simultaneously attained. Multivariate logistic regression analysis was performed for testing potential variables that were associated with a failure in attaining early (i.e., at first TDM assessment) optimal PK/PD targets. (3) Results: Overall, 77 critically ill OLT recipients (median age, 57 years; male, 63.6%; median MELD score at transplantation, 17 points) receiving a total of 100 beta-lactam treatment courses, were included. Beta-lactam therapy was targeted in 43% of cases. Beta-lactam dosing adjustments were provided in 76 out of 100 first TDM assessments (76.0%; 69.0% decreases and 7.0% increases), and overall, in 134 out of 245 total ECPAs (54.7%). Optimal PK/PD target was attained early in 88% of treatment courses, and throughout beta-lactam therapy in 89% of cases. Augmented renal clearance (ARC; OR 7.64; 95%CI 1.32-44.13) and MIC values above the EUCAST clinical breakpoint (OR 91.55; 95%CI 7.12-1177.12) emerged as independent predictors of failure in attaining early optimal beta-lactam PK/PD targets. (4) Conclusion: A real-time TDM-guided ECPA program allowed for the attainment of optimal beta-lactam PK/PD targets in approximately 90% of critically ill OLT recipients treated with CI beta-lactams during the early post-transplant period. OLT recipients having ARC or being affected by pathogens with MIC values above the EUCAST clinical breakpoint were at high risk for failure in attaining early optimal beta-lactam PK/PD targets. Larger prospective studies are warranted for confirming our findings.

Relationship Between Real-time TDM-guided Pharmacodynamic Target Attainment of Continuous Infusion Beta-lactam Monotherapy and Microbiologic Outcome in the Treatment of Critically Ill Children With Severe Documented Gram-negative Infections

OBJECTIVES

To explore the relationship between real-time therapeutic drug monitoring (TDM)-guided pharmacodynamic target attainment of continuous infusion (CI) beta-lactam monotherapy and microbiological outcome in the treatment of critically ill children with severe documented Gram-negative infections.

METHODS

Observational, monocentric, retrospective study of critically ill patients receiving CI piperacillin-tazobactam, ceftazidime, or meropenem in monotherapy for documented Gram-negative infections optimized by means of a real-time TDM-guided strategy. Average steady-state beta-lactam concentrations (C ss ) were calculated for each patient, and the beta-lactam C ss /minimum inhibitory concentration (MIC) ratio was selected as a pharmacodynamic parameter of efficacy. The C ss /MIC ratio was defined as optimal if ≥4, quasi-optimal if between 1 and 4, and suboptimal if <1. The relationship between C ss /MIC and microbiological outcome was assessed.

RESULTS

Forty-six TDM assessments were carried out in 21 patients [median age 2 (interquartile range: 1-8) years]. C ss /MIC ratios were optimal in 76.2% of cases. Patients with optimal C ss /MIC ratios had both a significantly higher microbiological eradication rate (75.0% vs. 0.0%; P = 0.006) and lower resistance development rate (25.0% vs. 80.0%; P = 0.047) than those with quasi-optimal or suboptimal C ss /MIC ratios. Quasi-optimal/suboptimal C ss /MIC ratio occurred more frequently when patients had infections caused by pathogens with MIC values above the European Committee on Antimicrobial Susceptibility Testing clinical breakpoint (100.0% vs. 6.3%; P < 0.001).

CONCLUSIONS

Real-time TDM-guided pharmacodynamic target attainment of CI beta-lactam monotherapy allowed to maximize treatment efficacy in most critically ill children with severe Gram-negative infections. Attaining early optimal C ss /MIC ratios of CI beta-lactams could be a key determinant associated with microbiologic eradication during the treatment of Gram-negative infections. Larger prospective studies are warranted for confirming our findings.

Real-Time TDM-Based Expert Clinical Pharmacological Advice Program for Attaining Aggressive Pharmacokinetic/Pharmacodynamic Target of Continuous Infusion Meropenem in the Treatment of Critically Ill Patients with Documented Gram-Negative Infections Undergoing Continuous Veno-Venous Hemodiafiltration

(1) Objectives: to describe the pharmacokinetic/pharmacodynamic (PK/PD) profile of continuous infusion (CI) meropenem in critical patients with documented Gram-negative infections undergoing continuous veno-venous hemodiafiltration (CVVHDF) and to assess the relationship with microbiological outcome. (2) Methods: Data were retrospectively retrieved for patients admitted to the general and the post-transplant intensive care units in the period October 2022-May 2023 who underwent CVVHDF during treatment with CI meropenem optimized by means of a real-time therapeutic drug monitoring (TDM)-based expert clinical pharmacological advice (ECPA) program for documented Gram-negative infections. Steady-state meropenem plasma concentrations were measured, and the free fractions (fCss) were calculated. Meropenem total clearance (CLtot) was calculated at each TDM assessment, and the impact of CVVHDF dose intensity and of residual diuresis on CLtot was investigated by means of linear regression. Optimal meropenem PK/PD target attainment was defined as an fCss/MIC ratio > 4. The relationship between meropenem PK/PD target attainment and microbiological outcome was assessed. (3) Results: A total of 24 critical patients (median age 68 years; male 62.5%) with documented Gram-negative infections were included. Median (IQR) meropenem fCss was 19.9 mg/L (17.4-28.0 mg/L). Median (IQR) CLtot was 3.89 L/h (3.28-5.29 L/h), and median (IQR) CVVHDF dose intensity was 37.4 mL/kg/h (33.8-44.6 mL/kg/h). Meropenem dosing adjustments were provided in 20 out of 24 first TDM assessments (83.3%, all decreases) and overall in 26 out of the 51 total ECPA cases (51.0%). Meropenem PK/PD target attainment was always optimal, and microbiological eradication was achieved in 90.5% of assessable cases. (4) Conclusion: the real-time TDM-guided ECPA program was useful in attaining aggressive PK/PD targeting with CI meropenem in critically ill patients undergoing high-intensity CVVHDF and allowed microbiological eradication in most cases with dosing regimens ranging between 125 and 500 mg q6h over 6 h.

Loading dose plus continuous/extended infusion versus intermittent bolus of β-lactams for the treatment of Gram-negative bacteria bloodstream infections: a propensity score-adjusted retrospective cohort study

BACKGROUND

Optimal β-lactam dosing for the treatment of Gram-negative bacteria bloodstream infections (GNB-BSIs) remains a debated issue. Herein, the efficacy and safety of a loading dose (LD) followed by extended/continuous infusion (EI/CI) versus intermittent bolus (IB) of these drugs for the treatment of GNB-BSIs was evaluated.

METHODS

This is a retrospective observational study enrolling patients with GNB-BSIs treated with β-lactams from 1 October 2020 to 31 March 2022. The 30 day infection-related mortality rate was assessed with Cox regression, while mortality risk reduction was evaluated by an inverse probability of treatment weighting regression adjustment (IPTW-RA) model.

RESULTS

Overall, 224 patients were enrolled: 140 and 84 in the IB and EI/CI groups, respectively. β-Lactam regimens were chosen according to pathogen antibiogram, clinical judgement and current guidelines. Interestingly, the LD + EI/CI regimen was associated with a significant lower mortality rate (17% versus 32%, P = 0.011). Similarly, β-lactam LD + EI/CI was significantly associated with a reduced risk of mortality at multivariable Cox regression [adjusted HR (aHR) = 0.46; 95%CI = 0.22-0.98; P = 0.046]. Finally, the IPTW-RA (adjusted for multiple covariates) was performed, showing a significant risk reduction in the overall population [-14% (95% CI = -23% to -5%)]; at the subgroup restricted analysis, a significant risk reduction (>15%) was observed in the case of GNB-BSI in severely immunocompromised patients (P = 0.003), for SOFA score > 6 (P = 0.014) and in septic shock (P = 0.011).

CONCLUSIONS

The use of LD + EI/CI of β-lactams in patients with a GNB-BSI may be associated with reduced mortality; also in patients with severe presentation of infection or with additional risk factors, such as immunodepression.

Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Piperacillin-Tazobactam or Meropenem and Microbiological Outcome among Urologic Patients with Documented Gram-Negative Infections

(1) Objectives: To describe the relationship between pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) piperacillin-tazobactam or meropenem monotherapy and microbiological outcome in a case series of urological patients with documented Gram-negative infections. (2) Methods: Patients admitted to the urology ward who were treated with CI piperacillin-tazobactam or meropenem monotherapy for documented Gram-negative infections and underwent real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program from June 2021 to May 2023 were retrospectively retrieved. Average steady-state (Css) piperacillin-tazobactam and meropenem concentrations were determined, and the free fractions (fCss) were calculated. Optimal PK/PD target attainments were defined as an fCss/MIC ratio >4 for CI meropenem and an fCss/MIC ratio of piperacillin >4 coupled with an fCss/CT ratio for tazobactam >1 for piperacillin-tazobactam (joint PK/PD target). The relationship between beta-lactam PK/PD targets and microbiological outcome was explored. (3) Results: Sixteen urologic patients with documented Gram-negative infections (62.5% complicated urinary tract infections (cUTI)) had 30 TDM-guided ECPAs. At first TDM assessment, beta-lactam dosing adjustments were recommended in 11 out of 16 cases (68.75%, of which 62.5% decreases and 6.25% increases). Overall, beta-lactam dosing adjustments were recommended in 14 out of 30 ECPAs (46.6%). Beta-lactam PK/PD target attainments were optimal in 100.0% of cases. Microbiological failure occurred in two patients, both developing beta-lactam resistance. (4) Conclusion: A TDM-guided ECPA program may allow for optimizing beta-lactam treatment in urologic patients with documented Gram-negative infections, ensuring microbiological eradication in most cases.

Safety of megadose meropenem in the empirical treatment of nosocomial sepsis: a pilot randomized clinical trial

Objective: To evaluate the safety of megadose meropenem as empirical treatment of nosocomial sepsis. Materials & methods: Critically ill patients diagnosed with sepsis received either high-dose (2 g every 8 h) or megadose (4 g every 8 h) meropenem as an intravenous infusion over 3 h. Results: A total of 23 patients with nosocomial sepsis were eligible and included in the megadose (n = 11) or high-dose (n = 12) group. No treatment-related adverse events were observed during a 14-day follow-up. Clinical response was also comparable between the groups. Conclusion: Megadose meropenem may be considered for empirical treatment of nosocomial sepsis without serious concern regarding its safety.

Individualised antimicrobial dose optimisation: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Therapeutic drug management (TDM) and model-informed precision dosing (MIPD) allow dose individualisation to increase drug effectivity and reduce toxicity.

OBJECTIVES

Evaluate the available evidence on the clinical efficacy of individualised antimicrobial dosing optimisation.

METHODS

Data sources: Pubmed, Embase, Web of Science, and Cochrane Library databases from database inception to the 11th of November 2022.

STUDY ELIGIBILITY CRITERIA

Published peer-reviewed Randomised Controlled Trials (RCTs).

PARTICIPANTS

Human subjects aged ≥18 years receiving an antibiotic or antifungal drug.

INTERVENTIONS

Patients receiving individualised antimicrobial dose adjustment. Assessment of risk of bias: Cochrane risk-of-bias tool for randomised trials (RoB2). Methods of data synthesis: Primary outcome was the risk of mortality. Secondary outcomes included target attainment, treatment failure, clinical and microbiological cure, length of stay, treatment duration and adverse events. Effect sizes were pooled using a random-effects model. Statistical heterogeneity was assessed by inconsistency testing (I²).

RESULTS

Ten RCTs were included in the meta-analysis (1,241 participants; n= 624 in the TDM group, n = 617 in the control group). Individualised antimicrobial dose optimisation was associated with a numerical decrease in mortality (RR = 0.86; 95% CI 0.71-1.05), without reaching statistical significance. Moreover, it was associated with significantly higher target attainment rates (RR = 1.41; 95% CI, 1.13-1.76) and a significant decrease in treatment failure (RR = 0.70; 95% CI, 0.54-0.92). Individualised antimicrobial dose optimisation was also associated with improvement, but not significant in clinical cure (RR = 1.33; 95% CI, 0.94-1.33) and microbiological outcome (RR = 1.25; CI, 1.00-1.57), as well as with a significant decrease in the risk of nephrotoxicity (RR = 0.55; 95% CI, 0.31-0.97).

CONCLUSIONS

This meta-analysis demonstrates that target attainment, treatment failure, and nephrotoxicity were significantly improved in patients who underwent individualised antimicrobial dose optimisation. However, it did not show a significant decrease in mortality, clinical cure or microbiological outcome.

Jumping into the future: overcoming pharmacokinetic/pharmacodynamic hurdles to optimize the treatment of severe difficult to treat-Gram-negative infections with novel beta-lactams

INTRODUCTION

The choice of best therapeutic strategy for difficult-to-treat resistance (DTR) Gram-negative infections currently represents an unmet clinical need.

AREAS COVERED

This review provides a critical reappraisal of real-world evidence supporting the role of pharmacokinetic/pharmacodynamic (PK/PD) optimization of novel beta-lactams in the management of DTR Gram-negative infections. The aim was to focus on prolonged and/or continuous infusion administration, penetration rates into deep-seated infections, and maximization of PK/PD targets in special renal patient populations. Retrieved findings were applied to the three most critical clinical scenarios of Gram-negative resistance phenotypes (i.e. carbapenem-resistant Enterobacterales; difficult-to-treat resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii).

EXPERT OPINION

Several studies supported the role of PK/PD optimization of beta-lactams in the management of DTR Gram-negative infections for both maximizing clinical efficacy and preventing resistance emergence. Optimizing antimicrobial therapy with novel beta-lactams based on the so called 'antimicrobial therapy puzzle' PK/PD concepts may represent a definitive jump into the future toward a personalized patient management of DTR Gram negative infections. Establishing a dedicated and coordinated multidisciplinary team and implementing a real-time TDM-guided personalized antimicrobial exposure optimization of novel beta-lactams based on expert clinical pharmacological interpretation, could represent crucial cornerstones for the proper management of DTR Gram-negative infections.