Treatment of invasive fungal infections in intensive care units with micafungin: The MYRIADE study

Association of doses based on body constitutional parameters with the efficacy of micafungin in candidemia

BACKGROUND

Invasive candidiasis is a life-threatening infection associated with high mortality, necessitating early and effective treatment. Micafungin, an echinocandin, is recommended as initial therapy for invasive candidiasis. However, the optimal micafungin dose relative to patients' body constitutional parameters (BCPs) remains unclear. This study aimed to evaluate the relationship between the dose of micafungin per BCPs (Dose/BCPs) and treatment outcomes.

METHODS

This two-center retrospective study included patients treated with micafungin who had confirmed positive blood cultures for Candida species between January 1, 2010, and December 31, 2020. We assessed the association between Dose/BCP and treatment success, as well as time to recovery following micafungin therapy.

RESULTS

Eighty-three patients were included in the analysis, with a median age of 78 years. The primary isolated Candida species were Candida albicans (n = 34), Candida parapsilosis (n = 19), and Candida glabrata (n = 16). The treatment success rate was 44.6 % and was significantly associated with age ≥75 years. Although no significant differences in Dose/BCP were observed between the success and failure groups, patients with a Dose/BSA ≥100 mg/m2 experienced a significantly shorter time to recovery with micafungin therapy.

CONCLUSION

Our study identified an association between Dose/BSA and the time to recovery with micafungin therapy. While some missing data, including APACHE-II scores, limit the robustness of the findings because of the retrospective design, dose adjustment to achieve Dose/BSA ≥100 mg/m2 may be beneficial in antifungal stewardship. This adjustment could reduce treatment duration with this broad-spectrum antifungal agent.

An improved expression and purification protocol enables the structural characterization of Mnt1, an antifungal target from Candida albicans

BACKGROUND

Candida albicans is one of the most prevalent fungi causing infections in the world. Mnt1 is a mannosyltransferase that participates in both the cell wall biogenesis and biofilm growth of C. albicans. While the cell wall performs crucial functions in pathogenesis, biofilm growth is correlated with sequestration of drugs by the extracellular matrix. Therefore, antifungals targeting CaMnt1 can compromise fungal development and potentially also render Candida susceptible to drug therapy. Despite its importance, CaMnt1 has not yet been purified to high standards and its biophysical properties are lacking.

RESULTS

We describe a new protocol to obtain high yield of recombinant CaMnt1 in Komagataella phaffii using methanol induction. The purified protein's identity was confirmed by MALDI-TOF/TOF mass spectroscopy. The Far-UV circular dichroism (CD) spectra demonstrate that the secondary structure of CaMnt1 is compatible with a protein formed by α-helices and β-sheets at pH 7.0. The fluorescence spectroscopy results show that the tertiary structure of CaMnt1 is pH-dependent, with a greater intensity of fluorescence emission at pH 7.0. Using our molecular modeling protocol, we depict for the first time the ternary complex of CaMnt1 bound to its two substrates, which has enabled the identification of residues involved in substrate specificity and catalytic reaction. Our results corroborate the hypothesis that Tyr209 stabilizes the formation of an oxocarbenium ion-like intermediate during nucleophilic attack of the acceptor sugar, opposing the double displacement mechanism proposed by other reports.

CONCLUSIONS

The methodology presented here can substantially improve the yield of recombinant CaMnt1 expressed in flask-grown yeasts. In addition, the structural characterization of the fungal mannosyltransferase presents novelties that can be exploited for new antifungal drug's development.