Micafungin twice-a-week for prophylaxis of invasive Aspergillus infections in children with acute lymphoblastic leukaemia: A controlled cohort study

OBJECTIVES

Invasive Aspergillus infections during the early phase of childhood acute lymphoblastic leukemia (ALL) treatment come with morbidity and mortality. The interaction with vincristine hampers first-line azole prophylaxis. We describe the efficacy of an alternative twice-a-week micafungin regimen for Aspergillus prophylaxis.

METHODS

Newly diagnosed paediatric patients with ALL treated according to the ALL-11 protocol received micafungin twice-a-week (9 mg/kg/dose [max. 300 mg]) during the induction course (first 35 days of treatment) as part of routine care. A historical control cohort without Aspergillus prophylaxis was used. During the first consolidation course (day 36-79), standard itraconazole prophylaxis was used in both groups. The percentage of proven/probable Aspergillus infections during the induction/first consolidation course was compared between the cohorts. The cumulative incidence of proven/probable Aspergillus infections was estimated using a competing risk model. For safety evaluation, liver laboratory chemistry values were analysed.

RESULTS

A total of 169 and 643 paediatric patients with ALL were treated in the micafungin cohort (median age: 4 years [range 1-17]) and historical cohort (median age: 5 years [range 1-17]). The percentage of proven/probable Aspergillus infections was 1·2% (2/169) in the micafungin cohort versus 5·8% (37/643) in the historical cohort (p=0.013; Fisher's exact test). The differences in estimated cumulative incidence were assessed (p=0·014; Gray's test). Although significantly higher ALT/AST values were reported in the micafungin cohort, no clinically relevant side effects were observed.

CONCLUSIONS

Twice-a-week micafungin prophylaxis during the induction course significantly reduced the occurrence of proven/probable Aspergillus infections in the early phase of childhood ALL treatment.

Liposomal amphotericin B-the past

The discovery of amphotericin B, a polyene antifungal compound, in the 1950s, and the formulation of this compound in a liposomal drug delivery system, has resulted in decades of use in systemic fungal infections. The use of liposomal amphotericin B formulation is referenced in many international guidelines for the treatment of fungal infections such as Aspergillus and cryptococcal disease and Candida infections, as well as other less common infections such as visceral leishmaniasis. With the development of liposomal amphotericin B, an improved therapeutic index could be achieved that allowed the attainment of higher drug concentrations in both the plasma and tissue while simultaneously lowering the toxicity compared with amphotericin B deoxycholate. In over 30 years of experience with this drug, a vast amount of information has been collected on preclinical and clinical efficacy against a wide variety of pathogens, as well as evidence on its toxicity. This article explores the history and nature of the liposomal formulation, the key clinical studies that developed the pharmacokinetic, safety and efficacy profile of the liposomal formulation, and the available microbiological data.

First international quality control programme for laboratories measuring antimicrobial drugs to support dose individualization in critically ill patients

Objectives

International quality control (proficiency testing) programmes are instituted to safeguard the analytical performance of laboratories and to aid these laboratories in identifying sources of error in their analytical methods. We describe the first international quality control programme for antimicrobial agents that are frequently used in critically ill patients.

Methods

Spiked plasma samples with ceftazidime, ciprofloxacin, flucloxacillin, piperacillin, sulfamethoxazole, N-acetyl sulfamethoxazole and trimethoprim were shipped to 22 laboratories from eight different countries. Acceptable accuracy by the performing laboratory was defined if measurements were within 80%–120% limits of the true weighed-in concentrations.

Results

A total of 81% of the measurements (ranging between 56% and 100%, dependent on drug) were within the 80%–120% limits of the true weighed-in concentrations.

Conclusions

We found a relatively good performance of the participating laboratories in measuring eight different antimicrobial drugs. Nevertheless, some of the antimicrobial drugs were not measured properly as up to 44% of the measurements was inaccurate depending on the drug. Our results emphasize the need for and utility of an ongoing quality control programme.

Invasive pulmonary aspergillosis associated with viral pneumonitis

The occurrence of invasive pulmonary aspergillosis (IPA) in critically ill patients with viral pneumonitis has increasingly been reported in recent years. Influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are the two most common forms of this fungal infection. These diseases cause high mortality in patients, most of whom were previously immunocompetent. The pathogenesis of IAPA and CAPA is still not fully understood, but involves viral, fungal and host factors. In this article, we discuss several aspects regarding IAPA and CAPA, including their possible pathogenesis, the use of immunotherapy, and future challenges.

Nephrotoxicity of concomitant piperacillin/tazobactam and teicoplanin compared with monotherapy

OBJECTIVES

Piperacillin/tazobactam combined with vancomycin has been associated with a decline in renal function when compared with monotherapy. Teicoplanin is a glycopeptide similar to vancomycin. We investigated whether piperacillin/tazobactam combined with teicoplanin is associated with a decline in renal function as well.

METHODS

We conducted a single-centre retrospective cohort study with data from our electronic health records from 9 August 2013 to 15 November 2019, including all adult patients that received either piperacillin/tazobactam, teicoplanin or piperacillin/tazobactam + teicoplanin. The incidence of acute kidney injury (AKI) at 48-72 h served as the primary outcome, whereas change in serum creatinine served as a secondary outcome.

RESULTS

Of the 4202 included patients, 3188 (75.9%) received piperacillin/tazobactam, 791 (18.8%) received teicoplanin and 223 (5.3%) received piperacillin/tazobactam + teicoplanin. The incidence of AKI at 48-72 h after commencement of antibiotic therapy was 5.4% for piperacillin/tazobactam, 3.4% for teicoplanin and 11.7% for piperacillin/tazobactam + teicoplanin (P < 0.001). However, mean serum creatinine at 48-72 h was slightly higher in the piperacillin/tazobactam + teicoplanin group therapy compared with baseline [+1.61% (95% CI -2.25 to 5.70)], indicating a slight decrease in renal function, and decreased for piperacillin/tazobactam [-1.98% (95% CI -2.73 to -1.22)] and teicoplanin [-8.01% (95% CI -9.54 to -6.45)]. After correcting for significant confounders in a multivariate linear regression analysis, these patterns remained.

CONCLUSIONS

Our study suggests that piperacillin/tazobactam + teicoplanin is associated with a higher prevalence of AKI compared with monotherapy. However, as the overall decline in renal function with piperacillin/tazobactam + teicoplanin is very small, its clinical relevance is likely limited. Therefore, piperacillin/tazobactam + teicoplanin can probably be safely combined.

Management of cerebral azole-resistant Aspergillus fumigatus infection: A role for intraventricular liposomal-amphotericin B

OBJECTIVES

In the pre-azole era, central nervous system (CNS) infections with Aspergillus had a dismal outcome. Survival improved with voriconazole but CNS infections caused by azole-resistant Aspergillus fumigatus preclude its use. Intravenous liposomal-amphotericin B (L-AmB) is the preferred treatment option for azole-resistant CNS infections but has suboptimal brain concentrations.

METHODS

We describe three patients with biopsy-proven CNS aspergillosis where intraventricular L-AmB was added to systemic therapy. Two patients with azole-resistant aspergillosis and one patient with azole-susceptible CNS aspergillosis were treated with intraventricular L-AmB at a dose of 1mg weekly.

RESULTS

We describe three patients successfully treated with a combination of intravenous and intraventricular L-AmB. All three patients survived but one patient developed serious headaches, most likely not related to this treatment.

CONCLUSIONS

Intraventricular L-AmB may have a role in the treatment of therapy-refractory CNS aspergillosis when added to systemic therapy.

The role of infection models and PK/PD modelling for optimising care of critically ill patients with severe infections

Critically ill patients with severe infections are at high risk of suboptimal antimicrobial dosing. The pharmacokinetics (PK) and pharmacodynamics (PD) of antimicrobials in these patients differ significantly from the patient groups from whose data the conventional dosing regimens were developed. Use of such regimens often results in inadequate antimicrobial concentrations at the site of infection and is associated with poor patient outcomes. In this article, we describe the potential of in vitro and in vivo infection models, clinical pharmacokinetic data and pharmacokinetic/pharmacodynamic models to guide the design of more effective antimicrobial dosing regimens. Individualised dosing, based on population PK models and patient factors (e.g. renal function and weight) known to influence antimicrobial PK, increases the probability of achieving therapeutic drug exposures while at the same time avoiding toxic concentrations. When therapeutic drug monitoring (TDM) is applied, early dose adaptation to the needs of the individual patient is possible. TDM is likely to be of particular importance for infected critically ill patients, where profound PK changes are present and prompt appropriate antibiotic therapy is crucial. In the light of the continued high mortality rates in critically ill patients with severe infections, a paradigm shift to refined dosing strategies for antimicrobials is warranted to enhance the probability of achieving drug concentrations that increase the likelihood of clinical success.

Mechanism of oxime reactivation of acetylcholinesterase analyzed by chirality and mutagenesis

Organophosphates inactivate acetylcholinesterase by reacting covalently with the active center serine. We have examined the reactivation of a series of resolved enantiomeric methylphosphonate conjugates of acetylcholinesterase by two oximes, 2-pralidoxime (2-PAM) and 1-(2'-hydroxyiminomethyl-1'-pyridinium)-3-(4'-carbamoyl-1-pyridinium) (HI-6). The S(p) enantiomers of the methylphosphonate esters are far more reactive in forming the conjugate with the enzyme, and we find that rates of oxime reactivation also show an S(p) versus R(p) preference, suggesting that a similar orientation of the phosphonyl oxygen toward the oxyanion hole is required for both efficient inactivation and reactivation. A comparison of reactivation rates of (S(p))- and (R(p))-cycloheptyl, 3,3-dimethylbutyl, and isopropyl methylphosphonyl conjugates shows that steric hindrance by the alkoxy group precludes facile access of the oxime to the tetrahedral phosphorus. To facilitate access, we substituted smaller side chains in the acyl pocket of the active center and find that the Phe295Leu substitution enhances the HI-6-elicited reactivation rates of the S(p) conjugates up to 14-fold, whereas the Phe297Ile substitution preferentially enhances 2-PAM reactivation by as much as 125-fold. The fractional enhancement of reactivation achieved by these mutations of the acyl pocket is greatest for the conjugated phosphonates of the largest steric bulk. By contrast, little enhancement of the reactivation rate is seen with these mutants for the R(p) conjugates, where limitations on oxime access to the phosphonate and suboptimal positioning of the phosphonyl oxygen in the oxyanion hole may both slow reactivation. These findings suggest that impaction of the conjugated organophosphate within the constraints of the active center gorge is a major factor in influencing oxime access and reactivation rates. Moreover, the individual oximes differ in attacking orientation, leading to the presumed pentavalent transition state. Hence, their efficacies as reactivating agents depend on the steric bulk of the intervening groups surrounding the tetrahedral phosphorus.