Efficacy and Associated Drug Exposures of Isavuconazole and Fluconazole in an Experimental Model of Coccidioidomycosis

A microbial risk assessor's guide to Valley Fever (Coccidioides spp.): Case study and review of risk factors

Valley Fever is a respiratory disease caused by inhalation of arthroconidia, a type of spore produced by fungi within the genus Coccidioides spp. which are found in dry, hot ecosystems of the Western Hemisphere. A quantitative microbial risk assessment (QMRA) for the disease has not yet been performed due to a lack of dose-response models and a scarcity of quantitative occurrence data from environmental samples. A literature review was performed to gather data on experimental animal dosing studies, environmental occurrence, human disease outbreaks, and meteorological associations. As a result, a risk framework is presented with information for parameterizing QMRA models for Coccidioides spp., with eight new dose-response models proposed. A probabilistic QMRA was conducted for a Southwestern US agricultural case study, evaluating eight scenarios related to farming occupational exposures. Median daily workday risks for developing severe Valley Fever ranged from 2.53 × 10-7 (planting by hand while wearing an N95 facemask) to 1.33 × 10-3 (machine harvesting while not wearing a facemask). The literature review and QMRA synthesis confirmed that exposure to aerosolized arthroconidia has the potential to result in high attack rates but highlighted that the mechanistic relationships between environmental conditions and disease remain poorly understood. Recommendations for Valley Fever risk assessment research needs in order to reduce disease risks are discussed, including interventions for farmers.

Isavuconazole in the Treatment of Chronic Forms of Coccidioidomycosis

Coccidioidomycosis is a fungal infection with a range of clinical manifestations. Currently used antifungal agents exhibit variable efficacy and toxicity profiles that necessitate evaluation of additional therapeutic options. Improvement was observed in the majority of patients treated with isavuconazole, with clinical failures observed only in those with coccidioidal meningitis.

Can fluconazole be used for inpatient re-treatment of coccidioidomycosis among patients with past fluconazole exposures?

BACKGROUND

Coccidioides spp. may cause significant disease requiring hospitalisation, but optimal antifungal therapy among inpatients following outpatient fluconazole exposures is unknown.

OBJECTIVES

The objective of this study is to describe the effectiveness of fluconazole among patients hospitalised for coccidioidomycosis despite recent outpatient fluconazole treatment.

PATIENTS/METHODS

Patients were admitted to an academic medical center in Phoenix, Arizona from 1 January 2013 through 31 December 2020 for coccidioidomycosis following at least 30 days of outpatient treatment and re-initiation of fluconazole upon admission. The primary outcome was the proportion of patients with an improved response per the change in the modified Mycosis Study Group (MSG) score (a composite of symptoms, serology and radiographic findings) and clinician impressions.

RESULTS

Sixty-seven patients were included, with most (54%) admitted to the intensive care unit. Meningitis was the most common infectious presentation (55%), 17 patients (25%) had multiple infection sites, and 23 (34%) were culture-positive for Coccidioides. Upon admission, the median (IQR) MSG score was 11 (9-14), which dropped to 4 (1-7) at end of therapy or last follow-up. Overall, after initiation of fluconazole therapy at a median daily dose of 800 mg, 48 patients (72%) improved in overall status, 10 (15%) showed stable disease and 9 (13%) were unresponsive. Improved response rates were high across all infection sites, including meningitis (68%) and bone infection (71%). There was no significant difference in response rates between patients with and without reported outpatient fluconazole nonadherence.

CONCLUSIONS

The majority of patients admitted to the hospital for coccidioidomycosis appeared responsive to fluconazole therapy despite past outpatient exposures.

New Perspectives on Antimicrobial Agents: Isavuconazole

Isavuconazole is the newest of the clinically available advanced generation triazole antifungals and is active against a variety of yeasts, molds, and dimorphic fungi. Its current FDA-approved indications include the management of invasive aspergillosis as well as mucormycosis, though the latter indication is supported by limited clinical data. Isavuconazole did not achieve noninferiority to caspofungin for the treatment of invasive candidiasis and therefore lacks an FDA-approved indication for this invasive disease. Significant advantages of isavuconazole, primarily over voriconazole but in some circumstances posaconazole as well, make it an appealing option for the management of complex patients with invasive fungal infections. These potential advantages include lack of QTc interval prolongation, more predictable pharmacokinetics, a less complicated drug interaction profile, and improved tolerability, particularly when compared to voriconazole. This review discusses these topics in addition to addressing the in vitro activity of the compound against a variety of fungi and provides insight into other distinguishing factors among isavuconazole, voriconazole, and posaconazole. The review concludes with an opinion section in which the authors provide the reader with a framework for the current role of isavuconazole in the antifungal armamentarium and where further data are required.

Controversies in the Management of Central Nervous System Coccidioidomycosis

Central nervous system infection with Coccidioides spp is fatal if untreated, and complications occur even when therapy is directed by experienced clinicians. We convened a panel of clinicians experienced in the management of coccidioidal meningitis to summarize current controversies and provide consensus for the management of this difficult infection.

Current Landscape of Coccidioidomycosis

Coccidioidomycosis, also known as Valley fever, is an endemic fungal infection commonly found in the southwestern parts of the United States. However, the disease has seen an increase in both in its area of residency and its prevalence. This review compiles some of the latest information on the epidemiology, current and in-development pharmaceutical approaches to treat the disease, trends and projections, diagnostic concerns, and the overlapping dynamics of coccidioidomycosis and COVID-19, including in special populations. This review provides an overview of the current diagnostic and therapeutic strategies and identifies areas of future development.

Efficacy of nikkomycin Z in murine CNS coccidioidomycosis: modelling sustained-release dosing

OBJECTIVES

Meningitis is the most feared coccidioidomycosis complication. Nikkomycin Z (nikZ) is a chitin synthase inhibitor. A concern is short half-life, necessitating multiple dose/day regimens. We simulated extended release, providing nikZ in drinking water. Extended release would enhance convenience, and adherence, for patients.

METHODS

Coccidioides posadasii was injected intracerebrally into mice. Twelve day treatments began on Day 3. Fluconazole was given 100 mg/kg once daily (gavage); designed doses of nikZ 30, 100 or 300 mg/kg/day in drinking water. On Day 30 post-treatment, survivors were euthanized, brain cfu quantitated and cfu in other organs assessed.

RESULTS

nikZ was stable in drinking water. Survival was 11%, 50%, 70%, 90% and 100% in untreated controls, fluconazole and nikZ 30, 100 and 300 mg/kg/day, respectively ; nikZ 300 mg/kg/day was superior (P ≤ 0.01) to fluconazole. Brains were sterilized in 0%, 20%, 86%, 89% and 80% of mice, respectively; nikZ 100 or 300 mg/kg/day was superior (P ≤ 0.01) to fluconazole. Clearance of infection in other organs was similar. All decreased drinking after infection, causing nikZ mice to ingest less than the desired dose in early therapy; despite this, they recovered sufficiently to resume pre-infection drinking and designed drug intakes. Thus, when sickest, even less than the designed dose was sufficient to enable recovery.

CONCLUSIONS

This efficacy supports the development of sustained-release nikZ. Decreased intake wouldn't be a factor in humans, receiving drug via extended-release pill or continuous IV infusion. In prior studies (twice daily nikZ) of murine coccidioidal meningitis, results were inferior, suggesting sustained release may provide both convenience and superior outcomes.