Anticandidal Effects of Zinc Oxide Nanoparticles on Fluconazole-Resistant Candida Isolates Causing Diarrhea in Calves, in vitro

Gastrointestinal disease in calves may pose a significant threat to the livestock industry. Due to the increased rate of resistance to antifungal drugs and the side effects of these drugs, it is essential to find suitable alternatives, such as nanoparticles, with favorable antifungal effects and few side effects. This study aimed to determine the frequency of yeast causing diarrhea in calves and evaluate zinc oxide nanoparticles' antifungal effects on fluconazole-resistant isolates. Fecal samples from 94 calves (age: < three months old) with clinical signs of diarrhea were examined by standard microbiological and biochemical methods. The broth microdilution method evaluated the susceptibility of fungi to fluconazole and the antimicrobial activity of zinc oxide nanoparticles on drug-resistant isolates. Candida albicans (41.63%) were calves' predominant cause of diarrhea. In addition, 51.2% of the C. albicans isolates were resistant to fluconazole. All fluconazole-resistant isolates were eliminated when treated with 119 μg/ml of zinc oxide nanoparticles. The prevalence of diarrhea is relatively high in calves. Considering the predominance of drug-resistant Candida and the favorable in vitro effects of zinc oxide nanoparticles against these isolates, it is recommended to investigate the effects of zinc oxide nanoparticles on these isolates in vivo.