A retrospective study of the prevalence of calcium oxalate crystals in veterinary Aspergillus cases.

This research investigates the prevalence of calcium oxalate crystals in various species affected by fungi in the genus Aspergillus. It shows that there is a significant occurrence of these crystals in infected species, suggesting that detection methods for these crystals during fungal infections should be improved.

Study Design and Species Selection

• The study reviewed past cases of Aspergillus infections in different animal species involving birds, horses, dogs, an ox and a dolphin.
• The cases were picked based on whether they had positive cultures for Aspergillus species or the presence of conidiophores, which belong to the Aspergillus genus.

Finding the Calcium Oxalate Crystals

• For each case, histologic slides were re-examined to confirm whether calcium oxalate crystals were present and if they were initially identified in the original report.
• Of the 38 reviewed cases, 14 were found to have a deposition of calcium oxalate crystals.
• These depositions were found in infection cases by various Aspergillus species, including A. fumigatus, A. versicolor, A. niger, and unspecified Aspergillus sp.

Specific Findings in Different Species

• The researchers discovered that 11 of the 16 bird species studied showed calcium oxalate crystals.
• The crystals were also found in one bovine case, one equine case, and one canine case.

Implications for Pathology Reporting

• Only 3 out of the 14 original pathology reports had noted the presence of these crystals, indicating that the identification and reporting of crystals in histologic specimens need improvement.
• All tissues containing crystals were respiratory tissues that interfaced with air, including the nasal sinus, trachea, syrinx (vocal organ in birds), lungs, and air sac.
• Also, the researchers observed that in cases stained with Gomori methenamine silver and periodic acid-Schiff, the crystals were often absent or less in number than in the tissue sections stained with H&E.

Recommendations for Future Practices

• The study suggests that polarization of slides should be routinely done during tests for fungal infections, especially in the respiratory tract, to check for the presence of calcium oxalate crystals.