Antifungal Susceptibility Testing Against Aspergillus flavus with Herbal Extracts and Synthetic Antifungals

Abstract

The globally distributed pathogenic fungus Aspergillus flavus poses a threat to both animal and human health. While synthetic antifungals have shown promise in controlling this fungus, their overuse has unfortunately led to a critical problem: the development of multidrug resistance, along with various other negative consequences. Therefore, alternative therapy is mandatory. This research sought to investigate the potential of herbal extracts, known for their antifungal properties, to serve as a complementary treatment to synthetic antifungals against A. flavus. Antifungal susceptibility tests were employed to evaluate this possibility. To isolate and identify A. flavus, fifty poultry feed samples underwent conventional culture methods and microscopic examination. Subsequently, the antifungal potential of five synthetic drugs (fluconazole, itraconazole, amphotericin B, nystatin, voriconazole) and eight herbal extracts (black seed, ginger, oregano, onion, turmeric, garlic, cinnamon, basil) was evaluated through disc diffusion assays and minimum inhibitory concentration (MIC) determination. Statistical analysis revealed voriconazole as the most effectual synthetic antifungal due to its highest zone of inhibition (39.53 ± 0.72) and lowest MIC value (0.12 ± 0). Hence, garlic amongst all herbs proved the best natural remedy with the highest inhibition zone value (25.83 ± 0.24) and lowest MIC score (0.66 ± 0.16) as per Clinical and Laboratory Standard Institute. Although synthetic antifungals gave better results than herbal extracts due to inconsistent, high financial exchange rates and lethal chemical residues, most of them are considered unsafe for humans. On the contrary, conventional complementary therapy, including herbal extracts, is harmless, affordable, eco-friendly, and has a lack of residual effects. Thus, more surveillance and research for the application of natural remedies are a supreme necessity.