Clinical effects of micafungin, a novel echinocandin antifungal agent, on systemic fungal infections in surgery, emergency, and intensive-care medicine: evaluation using the AKOTT algorithm

Leukopenia induced by micafungin in a bottlenose dolphin (Tursiops truncatus): a case report

A bottlenose dolphin (Tursiops truncatus) housed in the Port of Nagoya Public Aquarium (PNPA) presented with symptomatic pneumonia caused by Aspergillus fumigatus. The dolphin was treated with micafungin. On days 2 and 11 after the first administration of micafungin, results from a physical examination and laboratory test indicated a decline of body temperature (BT) and leukopenia, with lowest BT, white blood cells (WBCs), and segmented neutrophils (SEGs) of 34.2°C, 600 cells/µl, and 67 cells/µl, respectively. BT, WBCs, and SEGs returned to normal range after administration of granulocyte colony stimulating factor (G-CSF). To the best of our knowledge, this is the first report of micafungin-induced decline of BT and leukopenia that was successfully treated with G-CSF in a bottlenose dolphin.

The Role of Antifungals against Candida Biofilm in Catheter-Related Candidemia

Catheter-related bloodstream infection (C-RBSI) is one of the most frequent nosocomial infections. It is associated with high rates of morbidity and mortality. Candida spp. is the third most common cause of C-RBSI after coagulase-negative staphylococci and Staphylococcus aureus and is responsible for approximately 8% of episodes. The main cause of catheter-related candidemia is the ability of some Candida strains-mainly C. albicans and C. parapsilosis-to produce biofilms. Many in vitro and in vivo models have been designed to assess the activity of antifungal drugs against Candida biofilms. Echinocandins have proven to be the most active antifungal drugs. Potential options in situations where the catheter cannot be removed include the combination of systemic and lock antifungal therapy. However, well-designed and -executed clinical trials must be performed before firm recommendations can be issued.

Penetration of micafungin into the burn eschar in patients with severe burns

Micafungin (MCFG) concentrations in the plasma and in burn eschar were investigated after daily intravenous infusion (1 h) of MCFG (200 mg) in three patients with severe burns. MCFG treatment was initiated more than 72 h after the burn injuries. The MCFG concentrations in the plasma were determined at the end of the first administration of MCFG, immediately before the second dosing, at the end of the MCFG infusion after at least 4 days from the initial treatment, and immediately before the subsequent dosing using high-performance liquid chromatography. In addition, the trough levels in burn eschar after both the initial administration and repeated administration were measured. The peak and trough levels in the plasma were comparable to or slightly lower than the reported values in healthy volunteers. The mean (range) MCFG concentrations in the burn eschar after initial administration and repeated administration were 1.41 μg/mL (<0.1-3.98 μg/mL) and 6.65 μg/mL (1.10-14.81 μg/mL), respectively. In most cases, the MCFG concentrations in the burn eschar, especially after repeated administration, were higher than the reported MIC90 of MCFG against the clinically important pathogenic species of Candida and Aspergillus. These results suggest that MCFG is capable of penetrating burn eschar.

Efficacy and safety of liposomal amphotericin B for deep mycosis in patients with connective tissue disease

The efficacy and safety of liposomal amphotericin B (L-AMB) in the treatment of invasive fungal infections (IFIs) were retrospectively evaluated for patients with connective tissue diseases (CTDs) during treatment with immunosuppressive therapy. Subjects were 13 patients with CTDs complicated by IFI, on the basis of clinical symptoms, imaging findings, and microbiological and histological examinations. All patients were treated with L-AMB. Efficacy and safety were evaluated before and after administration of L-AMB. Underlying diseases were systemic lupus erythematosus for 4 patients, rheumatoid arthritis for 3, microscopic polyangiitis for 2, adult-onset Still disease for 1, dermatomyositis for 1, and mixed connective tissue disease for 1. Eight patients were resistant to other antifungal drugs. Prednisolone was given to 11 patients and the median dose was 10 mg/day. Immunosuppressants were used for 8 patients. The median duration of administration of L-AMB was 8.5 days (range 4-38 days). In proven and probable diagnosis patients (n = 5), the treatment was effective for 3 patients and ineffective for 2 (efficacy rate 60 %). Serum 1,3-β-D-glucan antigenemia (BG) levels decreased after treatment in the 2 patients who were positive for BG. Serum Aspergillus galactomannan antigen levels decreased in 3 of 4 patients with Aspergillus infection. No patient died of IFI. Regarding potential adverse reactions, there were no significant changes in serum creatinine and potassium levels. L-AMB is effective and well-tolerated for treatment of IFI in patients with CTDs.

Efficacy of micafungin in empirical therapy of deep mycosis in surgically ill patients

Micafungin (MCFG), an echinocandin antifungal agent, exhibits antifungal activity against Candida albicans and non-albicans Candida. The fungicidal activity of MCFG against clinical isolates of Candida species was investigated, and the clinical efficacy of MCFG in therapy of deep mycosis in surgery was studied using the AKOTT algorithm. The minimum inhibitory concentration and minimum fungicidal concentration values of fluconazole were ≤0.06-4 and >64 μg/ml, respectively, for each strain, whereas these values of MCFG were 0.008-0.5 and 0.016-1 μg/ml, suggesting that MCFG provided superior fungicidal ability against Candida albicans and non-albicans Candida. The subjects were separated into two groups: group A consisted of 20 subjects with both persisting fever refractory to broad-spectrum antibiotics and positive reaction to β-D-glucan test, and group B consisted of 20 subjects with either of those conditions. The overall response was evaluated as "effective" in 17 patients (85%) and 20 patients (100%) in groups A and B, respectively. In total, response was evaluated as "effective" in 37 patients (92.5%) and "ineffective" in 3 patients (7.5%). These findings suggest that MCFG administration should be used as empirical therapy for deep mycosis in surgically ill patients as it was shown to be an effective antifungal drug lacking serious adverse effects.

Synthesis of antifungal glucan synthase inhibitors from enfumafungin

An efficient, new, and scalable semisynthesis of glucan synthase inhibitors 1 and 2 from the fermentation product enfumafungin 3 is described. The highlights of the synthesis include a high-yielding ether bond-forming reaction between a bulky sulfamidate 17 and alcohol 4 and a remarkably chemoselective, improved palladium(II)-mediated Corey-Yu allylic oxidation at the highly congested C-12 position of the enfumafungin core. Multi-hundred gram quantities of the target drug candidates 1 and 2 were prepared, in 12 linear steps with 25% isolated yield and 13 linear steps with 22% isolated yield, respectively.

Clinical efficacy and safety of intravenous itraconazole in the management of invasive candidiasis in patients of surgery and critical care

Although itraconazole exhibits potent activity against Candida species, there have been few studies examining the use of intravenous itraconazole in the treatment of invasive candidiasis. A nationwide multicenter clinical study was conducted to evaluate the efficacy and safety of intravenous itraconazole in the management of invasive candidiasis, including non-albicans Candida species, in non-neutropenic patients undergoing surgery and critical care. Between September 2007 and August 2009, patients with proven and presumed candidiasis were enrolled at 22 participating institutions. Patients with presumed candidiasis had a deep-body temperature of 37.8°C or higher and were positive for serum β-D: -glucan or two or more colonization sites of Candida species. The main exclusion criterion was severe renal impairment (creatinine clearance <30 ml/min). The primary efficacy analysis was based on clinical and microbiological responses 5-10 days after the end of treatment, assessed by an independent data review committee. Of the 60 patients enrolled, 49 were included in the modified intention-to-treat population; 31 patients received a definitive diagnosis and 18 patients a presumed diagnosis. Intravenous itraconazole was used as first-line therapy to treat 39 patients and as second-line therapy for 10 patients. The isolated species included Candida albicans (25 strains with definitive diagnosis and 17 with presumed diagnosis) and non-albicans species (16 and 10, respectively). Treatment was successful in 61.5% patients (65.5% in first-line and 50.0% in second-line therapy); 60% of proven invasive candidiasis (IC) patients were judged as successful compared with 63.2% of presumed candidiasis patients. Eradication rate was 63.6% for C. albicans and 71.4% for C. glabrata. Adverse effects occurred in 9 of 60 patients (15.0%), commonly impaired liver function. The clinical efficacy and safety of intravenous itraconazole were suggested in the management of proven and presumed candidiasis including C. glabrata in non-neutropenic patients. The status of intravenous itraconazole in the Japanese guideline warrants reconsideration.

Micafungin concentrations in the plasma and burn eschar of severely burned patients

Micafungin concentrations in plasma and burn eschar after daily intravenous infusion (1 h) of micafungin (200 to 300 mg) were investigated for six patients with severe burns. Micafungin treatment was initiated more than 72 h after the burn injuries. The peak and trough levels in the plasma after the initial administration and repeated administrations for more than 4 days were comparable with or slightly lower than the reported values for healthy volunteers. Micafungin concentrations in the plasma and burn eschar were between 3.6 and >1,000 times higher than the reported MIC(90)s of micafungin against clinically important Candida and Aspergillus species.

Current perspectives on echinocandin class drugs

It has been nearly a decade since caspofungin was approved for clinical use as the first echinocandin class antifungal agent, followed by micafungin and anidulafungin. The echinocandin drugs target the fungal cell wall by inhibiting the synthesis of β-1,3-D-glucan, a critical cell wall component of many pathogenic fungi. They are fungicidal for Candida spp. and fungistatic for moulds, such as Aspergillus fumigatus, where they induce abnormal morphology and growth properties. The echinocandins have a limited antifungal spectrum but are highly active against most Candida spp., including azole-resistant strains and biofilms. As they target glucan synthase, an enzyme absent in mammalian cells, the echinocandins have a favorable safety profile. They show potent MIC and epidemiological cutoff values against susceptible Candida and Aspergillus isolates, and the frequency of resistance is low. When clinical breakthrough occurs, it is associated with high MIC values and mutations in Fks subunits of glucan synthase, which can reduce the sensitivity of the enzyme to the drug by several thousand-fold. Such strains were not adequately captured by an early clinical breakpoint for susceptibility prompting a revised lower value, which addresses the FKS resistance mechanism and new pharmacokinetic/pharmacodynamic studies. Elevated MIC values unlinked to therapeutic failure can occur and result from adaptive cell behavior, which is FKS-independent and involves the molecular chaperone Hsp90 and the calcineurin pathway. Mutations in FKS1 and/or FKS2 alter the kinetic properties of glucan synthase, which reduces the relative fitness of mutant strains causing them to be less pathogenic. The echinocandin drugs also modify the cell wall architecture exposing buried glucans, which in turn induce a variety of important host immune responses. Finally, the future for glucan synthase inhibitors looks bright with the development of new orally active compounds.

Evaluation of the safety and efficacy of micafungin in Japanese patients with deep mycosis: a post-marketing survey report

The safety and efficacy of micafungin were evaluated in a Japanese post-marketing survey involving 1,142 patients with deep mycosis caused by Candida or Aspergillus. The overall clinical response was 83.0%, and the respective responses for patients with candidiasis or aspergillosis were 86.3 and 70.8%. With regard to drug reactions, 562 adverse reactions were observed in 28.5% of patients. Among the 83 serious adverse drug reactions reported by 53 patients, a causal relationship with micafungin was assessed as definite or probable for 6 reactions in 5 patients. Age and baseline hepatic and renal function status did not affect the incidence of adverse reactions, although incidence increased significantly in proportion to the severity of mycosis and daily dose (p < 0.01). In multiple logistic regression analysis, neither baseline hepatic impairment nor increased daily dose of micafungin affected the incidence of hepatobiliary disorders, however, the severity of mycosis was found to correlate significantly with hepatobiliary disorders (p = 0.031). Taken together, our post-marketing findings show that micafungin is effective against deep mycosis caused by Candida or Aspergillus in patients across a range of backgrounds.