Population pharmacokinetics of piperacillin in critically ill children including those undergoing continuous kidney replacement therapy.

OBJECTIVES: Despite that piperacillin-tazobactam combination is commonly used in critically ill children, increasing evidence suggests that the current dosing schedules are not optimal for these patients. The aim of this work is to develop a population pharmacokinetic model for piperacillin to evaluate the efficacy of standard dosing in children with and without continuous kidney replacement therapy (CKRT) and to propose alternative dosing schemes maximizing target attainment. METHODS: Four hundred twenty-nine piperacillin concentrations measured in different matrices, obtained from 32 critically ill children (19 without CKRT, 13 with CKRT) receiving 100 mg/kg of piperacillin/tazobactam every 8 hours (increased to 12 hours after the fourth dose) were modelled simultaneously using the population approach with NONMEM 7.4. The percentage of patients with 90% fT > MIC and target attainment (percentage of dosing interval above MIC) were estimated for different intermittent and continuous infusions in the studied population. RESULTS: Piperacillin pharmacokinetic was best described with a two-compartment model. Renal, nonrenal, and hemofilter clearances were found to be influenced by the glomerular filtration rate, height (renal clearance), weight (nonrenal clearance), and filter surface (hemofilter clearance). Only seven (37%) children without CKRT and seven (54%) with CKRT achieved 90% fT > MIC with the current dosing schedule. Of the alternative regimens evaluated, a 24-hour continuous infusion of 200 mg/kg (CKRT) and 300 mg/kg (no CKRT) provided 100% fT > MIC (percent of time free drug remains above the minimum inhibitory concentration) (≤16 mg/L) and target attainments ≥90% across all evaluated MICs. DISCUSSION: In children with and without CKRT, standard dosing failed to provide an adequate systemic exposure, while prolonged and continuous infusions showed an improved efficacy.

A Case-Control Study of Real-Life Experience with Ceftolozane-Tazobactam in Patients with Hematologic Malignancy and Pseudomonas aeruginosa Infection.

We present our experience in patients with hematologic malignancy and Pseudomonas aeruginosa infection treated with ceftolozane-tazobactam. We performed a single-center case-control study comparing patients with hematologic malignancy and P. aeruginosa infection treated with ceftolozane-tazobactam (study group) with similar patients not treated with ceftolozane-tazobactam (control group) to assess safety and efficacy. Nineteen cases and 38 controls were analyzed. Cases were younger (45.6 years versus 57.6 years; P = 0.012) and less frequently had bacteremia (52.6% versus 86.8%; P = 0.008). They also had worse Multinational Association for Supportive Care in Cancer (MASCC) scores (10.2 versus 16.1; P = 0.0001), more hospital-acquired infections (78.9% versus 47.4%; P = 0.013), and more extremely drug-resistant (XDR) P. aeruginosa infections (47.4% versus 21.1%; P = 0.015). Cases received a median of 14 days (7 to 18 days) of ceftolozane-tazobactam (monotherapy in 11 cases [57.9.6%]). Ceftolozane-tazobactam was mostly used as targeted therapy (16 cases; 84.2%) because of resistance (9 cases; 47.4%), failure (4 cases; 21.1%), and toxicity (3 cases; 15.8%). Ten cases had bacteremia (52.6%). The sources were pneumonia (26.3%), catheter-related bacteremia (21.1%), primary bacteremia (21.1%), and perianal/genital (15.7%), urinary (10.5%), and skin/soft tissue (5.3%) infection. No toxicity was attributed to ceftolozane-tazobactam. More than 60% had neutropenia, and 15.8% fulfilled the criteria for sepsis. There were no significant differences in clinical cure at day 14 (89.5% versus 71.1%; P = 0.183) or recurrence (15.8% versus 10.5%; P = 0.675). Thirty-day mortality was lower among cases (5.3% versus 28.9%; P = 0.045). Ceftolozane-tazobactam was well tolerated and at least as effective as other alternatives for P. aeruginosa infection in patients with hematologic malignancy, including neutropenic patients with sepsis caused by XDR strains.

Initial use of echinocandins does not negatively influence outcome in Candida parapsilosis bloodstream infection: a propensity score analysis.

BACKGROUND: Concerns have arisen regarding the optimal antifungal regimen for Candida parapsilosis bloodstream infection (BSI) in view of its reduced susceptibility to echinocandins. METHODS: The Prospective Population Study on Candidemia in Spain (CANDIPOP) is a prospective multicenter, population-based surveillance program on Candida BSI conducted through a 12-month period in 29 Spanish hospitals. Clinical isolates were identified by DNA sequencing, and antifungal susceptibility testing was performed by the European Committee on Antimicrobial Susceptibility Testing methodology. Predictors for clinical failure (all-cause mortality between days 3 to 30, or persistent candidemia for ≥72 hours after initiation of therapy) in episodes of C. parapsilosis species complex BSI were assessed by logistic regression analysis. We further analyzed the impact of echinocandin-based regimen as the initial antifungal therapy (within the first 72 hours) by using a propensity score approach. RESULTS: Among 752 episodes of Candida BSI identified, 200 (26.6%) were due to C. parapsilosis species complex. We finally analyzed 194 episodes occurring in 190 patients. Clinical failure occurred in 58 of 177 (32.8%) of evaluable episodes. Orotracheal intubation (adjusted odds ratio [AOR], 2.81; P = .018) and septic shock (AOR, 2.91; P = .081) emerged as risk factors for clinical failure, whereas early central venous catheter removal was protective (AOR, 0.43; P = .040). Neither univariate nor multivariate analysis revealed that the initial use of an echinocandin-based regimen had any impact on the risk of clinical failure. Incorporation of the propensity score into the model did not change this finding. CONCLUSIONS: The initial use of an echinocandin-based regimen does not seem to negatively influence outcome in C. parapsilosis BSI.