Aspergillus fumigatus is a globally present pathogen capable of inflicting debilitating and life-threatening opportunistic infections in individuals, primarily those who are immunocompromised. Diagnosing A. fumigatus infections is often difficult, leading to a delay in treatment which can greatly impact patient outcomes. Furthermore, our lessening of antifungal development combined with increasing resistance generates a feasible scenario where only last resort options are viable. This has prompted the World Health Organization (WHO) to declare this pathogen a "critical priority" due to increased resistance and rising mortality rates. Azoles are utilized as primary treatment options for Aspergillus fumigatus infections such as voriconazole (VRC), itraconazole (ITC), and posaconazole (POS) with a reserve of Amphotericin B (AmB). In the past two decades, the emergence of resistance to azoles has contributed to a 90% mortality rate in resistant cases globally.
In this report, we investigated the MedChem Express (MCE) Drug Repurposing Compound Library (4,226 compounds) in conjunction with itraconazole at 0.06 µg/mL against A. fumigatus CDC #738. After the initial screening, we identified compounds known to be antifungals or antiseptics and deselected them. The remaining thirty selected compounds were evaluated through published literature and clinical trial data to determine those candidates with favorable characteristics/properties. Criteria for candidate selection consisted of evaluating the compounds; plasma concentration peak, the time to reach peak, protein binding, oral availability, and drug class. Six candidates were ranked the highest of the previous round –surprisingly 50% of those compounds were HIV drugs, cobicistat, elvitegravir, lopinavir. The remaining three selected compounds are penfluridol, rilapladib, and rolapitant.
The combination of itraconazole (ITC), posaconazole (POS), and voriconazole (VRC), with the identified compounds demonstrated promising amounts of synergy, in resistant and susceptible isolates.
Further investigation revealed novel properties of ITC and POS when in combination with our compounds of interest. Rilapladib was able to reverse POS, ITC, and VRC resistant strain(s) to a sensitive profile. Growth kinetic assays demonstrate potent anti-germination properties not seen before in the sub-inhibitory doses of azoles. This work demonstrates that high-throughput screening as a viable technique to identify robust antifungal synergizers, allowing for tenable translation to a clinical setting. / Master of Science / Aspergillus fumigatus is a worldwide fungal organism capable of causing disease, particularly in immunocompromised individuals. Infections primarily occur when individuals inhale spores that can remain dormant until the person's immune system is weakened, via disease, cancer, or prescribed drug for surgery. When the immune system is weakened, the spores are more effective at lung colonization. Aspergillus fumigatus infections can be combatted with voriconazole (VRC), itraconazole (ITC), or posaconazole (POS). However, in the past two decades, some fungi have started to develop resistance to azoles, necessitating the use of amphotericin B (AmB), a highly intolerable and final treatment option.
In this report, we challenged A. fumigatus CDC isolate #738 with compounds from the MedChem Express (MCE) Drug Repurposing Compound Library (4,226 compounds) with itraconazole at 0.06 µg/mL, an ineffective concentration. We selected combinations and compounds that negated 90% of fungal growth those combinations that contained a known antifungal or antiseptic agent; once identified we deselected any known antifungal or antiseptic agents. The remaining selected compounds were evaluated for favorable drug properties, by reviewing published literature and clinical reports to determine those candidates with favorable characteristics/properties. The combination of ITC, POS, and VRC with the identified compounds demonstrated antifungal enhancement in resistant and susceptible isolates.
We observed the reversal of resistance to POS, ITC, and VRC in several isolates when the drug combinations were applied. This demonstrates the importance of evaluating approved and under current review drugs to identify novel properties to aid our dwindling number of effective antifungals. This study provides promising combinational therapies for further evaluation in combating resistant A. fumigatus infections.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/117248 |
| Date | 20 December 2023 |
| Creators | Burns, Nicolas Dale |
| Contributors | Biomedical and Veterinary Sciences, Seleem, Mohamed Naguieb, Davis, Jennifer Lynn, Caswell, Clayton Christopher, Allen, Irving Coy |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
Page generated in 0.0024 seconds