We report and investigated a case of inadvertent contamination of 125 mice (housed in two germ-free positive-pressurized isolators) with emerging human and coral pathogen Aspergillus sydowii. The infected mice correspond to genetic line SAMP1/YitFc, which have 100% immune predisposition to develop Crohn's disease-like spontaneous pathologies, namely, inflammatory bowel disease (IBD). Pathogen update based on a scoping review of the literature and our clinical observations and experimentation are discussed. The unwanted infection of germ-free mice (immunologically prone to suffer chronic inflammation) with human pathogen A. sydowii resulted in no overt signs of clinical disease over 3-week exposure period, or during DSS-induced colitis experiments. Results and observations suggest that A. sydowii alone has limited clinical effect in immunocompromised germ-free mice or that other commensal microbial flora is required for Aspergillus-associated disease to occur.