Isavuconazole Is as Effective as and Better Tolerated Than Voriconazole for Antifungal Prophylaxis in Lung Transplant Recipients.

BACKGROUND: Invasive fungal infections (IFIs) are common following lung transplantation. Isavuconazole is unstudied as prophylaxis in organ transplant recipients. We compared effectiveness and tolerability of isavuconazole and voriconazole prophylaxis in lung transplant recipients. METHODS: A single-center, retrospective study of patients who received isavuconazole (September 2015-February 2018) or voriconazole (September 2013-September 2015) for antifungal prophylaxis. IFIs were defined by EORTC/MSG criteria. RESULTS: Patients received isavuconazole (n = 144) or voriconazole (n = 156) for median 3.4 and 3.1 months, respectively. Adjunctive inhaled amphotericin B (iAmB) was administered to 100% and 41% of patients in the respective groups. At 1 year, 8% of patients receiving isavuconazole or voriconazole developed IFIs. For both groups, 70% and 30% of IFIs were caused by molds and yeasts, respectively, and breakthrough IFI (bIFI) rate was 3%. Outcomes did not significantly differ for patients receiving or not receiving iAmB. Independent risk factors for bIFI and breakthrough invasive mold infection (bIMI) were mold-positive respiratory culture and red blood cell transfusion >7 units at transplant. Bronchial necrosis >2 cm from anastomosis and basiliximab induction were also independent risk factors for bIMI. Isavuconazole and voriconazole were discontinued prematurely due to adverse events in 11% and 36% of patients, respectively (P = .0001). Most common causes of voriconazole and isavuconazole discontinuation were hepatotoxicity and lack of oral intake, respectively. Patients receiving ≥90 days prophylaxis had fewer IFIs at 1 year (3% vs 9%, P = .02). IFIs were associated with increased mortality (P = .0001) and longer hospitalizations (P = .0005). CONCLUSIONS: Isavuconazole was effective and well tolerated as antifungal prophylaxis following lung transplantation.

Early Experience With Meropenem-Vaborbactam for Treatment of Carbapenem-resistant Enterobacteriaceae Infections.

Twenty patients with carbapenem-resistant Enterobacteriaceae infections were treated with meropenem-vaborbactam. Thirty-day clinical success and survival rates were 65% (13/20) and 90% (18/20), respectively. Thirty-five percent of patients had microbiologic failures within 90 days. One patient developed a recurrent infection due to meropenem-vaborbactam-nonsusceptible, ompK36 porin mutant Klebsiella pneumoniae.

Population Pharmacokinetics of Intravenous Isavuconazole in Solid-Organ Transplant Recipients.

Isavuconazole (ISA) is a triazole antifungal with activity against yeasts and molds. We established a population pharmacokinetic (pop PK) model of intravenous (i.v.) ISA to identify covariates that affect pharmacokinetics, using plasma samples from solid-organ transplant (SOT) recipients receiving peritransplant prophylaxis. Samples (n = 471) from 79 SOT recipients were utilized for pop PK analysis using nonlinear mixed-effect modeling NONMEM software. ISA (i.v.) PK parameters were best described by a two-compartment model. Significant covariates were sex on clearance (∼53% higher in women than men) and body mass index on peripheral volume of distribution. Incorporating drug exposure into Monte Carlo simulations, we demonstrated that standard ISA dosing is likely to attain the PK-pharmacodynamic (PD) target (area under the concentration curve/MIC ratio [AUC/MIC]) for treatment effectiveness against almost all infections caused by Aspergillus fumigatus isolates exhibiting MICs of ≤0.5 µg/ml (modal MIC). In contrast, standard dosing is predicted to attain PK-PD targets against <20% of infections caused by Candida albicans and Candida glabrata isolates exhibiting MICs of ≥0.016 and ≥0.5 µg/ml, respectively (modal MICs). These data are consistent with our SOT program's experience with ISA breakthrough infections, where 3 of 4 were caused by C. glabrata for which probabilities of PK-PD target attainment (PTA) were only 70% and 0% for isolates with MICs of 0.25 µg/ml and 1 µg/ml. Our findings provide important new insights into how ISA use might be optimized following SOT.

Achievement of clinical isavuconazole blood concentrations in transplant recipients with isavuconazonium sulphate capsules administered via enteral feeding tube.

BACKGROUND: Isavuconazole is a triazole antifungal available in IV and capsule formulation. Prescribing information states that capsules should not be chewed, crushed, dissolved or opened because the drug was not studied in this manner. However, considering the pharmacokinetics of the capsules, we theorized opening and sprinkling the contents into an enteral feeding tube (EFT) would result in adequate absorption and systemic concentrations of isavuconazole. OBJECTIVES: To determine whether patients receiving isavuconazonium sulphate capsules via EFT would achieve clinical blood concentrations of isavuconazole. METHODS: Nineteen solid organ and HCT recipients receiving isavuconazole via EFT for prevention or treatment of invasive fungal infection (IFI) were prospectively identified at four academic medical centres in the USA. Patients were included in this evaluation if they received isavuconazole via EFT for at least 5 days and therapeutic drug monitoring (TDM) was performed. RESULTS: TDM was performed after a median of 7 days (range 6-17) following EFT administration and 15 days (range 7-174) of isavuconazole therapy overall. Median isavuconazole concentration was 1.8 µg/mL (range 0.3-5.2). Median isavuconazole concentrations in patients with or without prior IV administration were 1.8 µg/mL (range 0.3-5.2) and 2.2 µg/mL (range 0.8-3.6; P = 0.896), respectively. Concentrations achieved with the EFT route were similar to or greater than the corresponding concentrations via the IV route in six patients who had TDM performed during both routes of administration. CONCLUSIONS: It is reasonable to consider opening isavuconazonium sulphate capsules and administering the contents enterally for prevention and treatment of IFI.

Pharmacokinetics of Intravenous Isavuconazole in Solid-Organ Transplant Recipients.

Isavuconazole may be useful in treating and preventing fungal infections in solid-organ transplant (SOT) recipients due to its safety profile and activity against Aspergillus and some Mucorales Isavuconazole has favorable pharmacokinetics based on clinical trials in various patient populations, but data are limited in SOT recipients. We evaluated the steady-state pharmacokinetics of isavuconazole in 26 SOT recipients receiving the drug intravenously for prophylaxis. There was moderate interpatient variability in isavuconazole pharmacokinetic parameters (coefficients of variation of 51% for the area under the plasma concentration-versus-time curve [AUC] and 59% for the trough plasma concentration [Ctrough]). AUC and steady-state Ctrough were significantly lower in women, patients with a body mass index of ≥18.5 kg/m2, and those receiving hemodialysis. Trough plasma concentrations were highly correlated with AUCs (R2 = 0.94) and can serve as a suitable measure of isavuconazole exposure in patients. In conclusion, moderate interpatient variability in isavuconazole exposure, the identification of factors associated with lower exposure, the recognition that Ctrough is a surrogate marker for AUC, and the availability of a simple analytical method suggest that therapeutic drug monitoring (TDM) may be useful for guiding treatment in at least some SOT recipients. Future studies are needed to correlate isavuconazole exposure with patients' clinical outcomes and to determine the clinical role of TDM.

Ceftazidime-Avibactam Is Superior to Other Treatment Regimens against Carbapenem-Resistant Klebsiella pneumoniae Bacteremia.

There are no data comparing outcomes of patients treated with ceftazidime-avibactam versus comparators for carbapenem-resistant Enterobacteriaceae infections. At our center, ceftazidime-avibactam treatment of carbapenem-resistant Klebsiella pneumoniae bacteremia was associated with higher rates of clinical success (P = 0.006) and survival (P = 0.01) than other regimens. Across treatment groups, there were no differences in underlying diseases, severity of illness, source of bacteremia, or strain characteristics (97% produced K. pneumoniae carbapenemase). Aminoglycoside- and colistin-containing regimens were associated with increased rates of nephrotoxicity (P = 0.002).

Clindamycin Plus Vancomycin Versus Linezolid for Treatment of Necrotizing Soft Tissue Infection.

Background: Necrotizing soft tissue infections (NSTIs) are life-threatening infections. The aim of this study is to evaluate the safety of clindamycin plus vancomycin versus linezolid as empiric treatment of NSTIs. Methods: This was a retrospective, single-center, quasi-experimental study of patients admitted from 1 June 2018 to 30 June 2019 (preintervention) and 1 May 2020 to 15 October 2021 (postintervention). Patients who received surgical management within 24 hours of NSTI diagnosis and at least 1 dose of linezolid or clindamycin were included. The primary endpoint was death at 30 days. The secondary outcomes included rates of acute kidney injury (AKI) and Clostridioides difficile infection (CDI). Results: A total of 274 patients were identified by admission diagnosis code for NSTI or Fournier gangrene; 164 patients met the inclusion criteria. Sixty-two matched pairs were evaluated. There was no difference in rates of 30-day mortality (8.06% vs 6.45%; hazard ratio [HR], 1.67 [95% confidence interval {CI}, .32-10.73]; P = .65). There was no difference in CDI (6.45% vs 1.61%; HR, Infinite [Inf], [95% CI, .66-Inf]; P = .07) but more AKI in the preintervention group (9.68% vs 1.61%; HR, 6 [95% CI, .73-276]; P = .05). Conclusions: In this small, retrospective, single-center, quasi-experimental study, there was no difference in 30-day mortality in patients receiving treatment with clindamycin plus vancomycin versus linezolid in combination with standard gram-negative and anaerobic therapy and surgical debridement for the treatment of NSTIs. A composite outcome of death, AKI, or CDI within 30 days was more common in the clindamycin plus vancomycin group.

Stewardship-Guided T2Candida Testing Shortens Time to Antifungal Treatment and Reduces Antifungal Usage Among Medical Intensive Care Unit Patients With Septic Shock.

Background: Diagnosis of invasive candidiasis (IC) is limited by insensitivity and slow turnaround of cultures. Our objectives were to define the performance of T2Candida, a nonculture test, under guidance of a diagnostic stewardship program, and evaluate impact on time to antifungal initiation and antifungal utilization. Methods: This was a retrospective study of adult medical intensive care unit (MICU) patients with septic shock for whom T2Candida testing was performed from March 2017 to March 2020. Patients with positive T2Candida results during this period were compared to MICU patients who did not undergo T2Candida testing but had septic shock and blood cultures positive for Candida from January 2016 through March 2020. Results: Overall, 155 T2Candida tests from 143 patients were included. Nine percent of T2Candida tests were positive compared to 4.5% of blood cultures. Sensitivity, specificity, positive predictive value, and negative predictive value of T2Candida for proven and probable IC were 78%, 95%, 50%, and 99%, respectively. Patients who tested positive for T2Candida (n = 14) were diagnosed earlier and initiated on antifungal therapy sooner than patients with IC (n = 14) diagnosed by blood culture alone (median, 5.6 vs 60 hours; P < .0001). Median antifungal days of therapy/1000 patient-days were 23.3/month preimplementation and 15/month postimplementation (P  = .007). Following a negative T2Candida result, empiric antifungals were either not administered in 58% or discontinued within 72 hours in 96% of patients. Conclusions: Diagnostic stewardship guided T2Candida testing resulted in reduced time to IC diagnosis, faster initiation of antifungal therapy, and lower antifungal usage among MICU patients with septic shock.