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Virulence factors of Candida spp. isolated from COVID-19 patients: hydrolytic enzyme activity and biofilm formation

Summary

During the COVID-19 pandemic, many hospitalized patients developed fungal infections caused by Candida yeasts alongside their coronavirus infection. Researchers studied 71 Candida samples from COVID-19 patients to understand how these fungi cause disease by examining three damaging enzymes they produce and their ability to form protective biofilm layers. The findings showed that these fungi are highly virulent, producing strong enzyme activity that helps them invade tissues and resist treatment, which helps explain why these infections are particularly dangerous in COVID-19 patients.

Background

During the COVID-19 pandemic, opportunistic fungal co-infections have emerged as serious complications in critically ill patients, with invasive candidiasis being a significant contributor to mortality. Candida spp. possess multiple virulence factors including hydrolytic enzymes and biofilm formation capacity that enhance their pathogenic potential in immunocompromised hosts.

Objective

This study aimed to assess the virulence factors of Candida spp. isolated from COVID-19 patients, specifically evaluating proteinase, phospholipase, and hemolysin activities as well as biofilm-forming capacity, and to explore associations with clinical parameters.

Results

All C. albicans strains and 95.45% of non-albicans Candida strains produced proteinase, 93.87% of C. albicans and 45.45% of non-albicans strains showed phospholipase activity, and all strains exhibited high hemolytic activity. Biofilm formation was detected in 43.66% of strains with weak to moderate intensity, with no significant associations found between virulence factors and clinical parameters.

Conclusion

Candida strains isolated from COVID-19 patients demonstrated high levels of hydrolytic enzyme activity, particularly proteinase and hemolysin, with variable biofilm formation. These findings highlight the importance of hydrolytic enzymes and biofilm formation in COVID-19-associated candidiasis pathogenesis and suggest the need for further research on therapeutic targets.
  • Published in:BMC Microbiology,
  • Study Type:Observational Laboratory Study,
  • Source: PMID: 41039201, DOI: 10.1186/s12866-025-04351-3
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