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Fungal keratitis complicating the diagnosis of Acanthamoeba keratitis

Summary

A 42-year-old farmer presented with a severe eye infection that was initially misdiagnosed as a viral infection caused by herpes simplex virus. When antiviral treatment failed, doctors discovered the patient had a fungal infection caused by Fusarium. However, advanced testing revealed she actually had a dual infection with both the fungus and a microscopic parasite called Acanthamoeba. The patient required corneal transplant surgery and combination therapy with multiple medications to control the infection and preserve vision.

Background

Acanthamoeba keratitis (AK) is a serious eye infection that can lead to significant visual damage and is challenging to diagnose due to early symptoms resembling other forms of keratitis such as herpes simplex virus infection. Coinfections of Acanthamoeba with fungi are more common than previously recognized and can occur in non-contact lens users, often requiring therapeutic keratoplasty.

Objective

This case report describes an unusual presentation of coinfection with both Acanthamoeba and fungal keratitis in a patient without contact lens use history. The study emphasizes the importance of considering Acanthamoeba infection in progressive and non-responsive infectious keratitis cases.

Results

Culture identified Fusarium sp. on day 5, but the patient did not respond to antifungal therapy. Histopathology and PCR analysis of corneal tissue obtained during therapeutic penetrating keratoplasty revealed both Acanthamoeba T4 genotype and Fusarium sp. DNA sequencing confirmed the T4 subgroup with greater than 95% similarity.

Conclusion

Acanthamoeba coinfections are more common than previously acknowledged and should be considered in cases of progressive or medically unresponsive keratitis. PCR molecular diagnostic testing is essential for accurate diagnosis, and early recognition of coinfections is crucial for appropriate treatment and visual outcomes.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 39811097, DOI: 10.1016/j.mmcr.2024.100687
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