Comparison of Broth Dilution and Disc Diffusion Method for the Antifungal Susceptibility Testing of Aspergillus flavus

With the discovery of newer antifungal agents, emergence of resistance among Aspergillus, is a major problem. In the present study, 25 different clinical isolates of Aspergillus flavus were screened for their susceptibility against five common antifungal agents by broth dilution and disc diffusion method with the aim to evaluate both the methods for their suitability to adapt in clinical laboratory. All the isolates showed susceptibility to five antifungals by broth dilution after 24 hrs however all isolates showed resistance for 5FC, fluconazole and ketoconazole after 48 hrs. By disc diffusion method, all isolates were sensitive for all antifungals except fluconazole which showed resistance even after 24 hrs. Amphotericin B and itraconazole were in good agreement between both the methods where 100% isolates were sensitive at both time period by broth dilution and 84% to 100% by disc diffusion method. Both the methods are in good agreement and since disc diffusion method is easy to perform, cheap, rapid and same can be adapted easily for the routine susceptibility testing of clinical fungal isolates in medical microbiology laboratory.