A patient presented with symptoms leading to suspicion of cryptococcal infection, prompting a lateral flow cryptococcal antigen assay (CrAg LFA). The assay returned a positive result, suggesting Cryptococcus. However, further investigation using metagenomic next-generation sequencing (mNGS) of the patient's samples revealed the presence of Trichosporon inkin, not Cryptococcus. This case highlights a critical diagnostic challenge where a commonly used rapid diagnostic test for Cryptococcus exhibited cross-reactivity with another fungal pathogen. The mNGS played a crucial role in correctly identifying the causative agent, preventing potential misdiagnosis and inappropriate treatment. This finding underscores the importance of confirmatory testing when unexpected results arise.
Key note: Lateral flow cryptococcal antigen assays can exhibit cross-reactivity with Trichosporon inkin, necessitating advanced diagnostic methods like mNGS for accurate pathogen identification.