Superficial abdominal surgical site infection caused by Aspergillus welwitschiae: a case report

Aspergillus spp. are rare causes of surgical site infections (SSIs). Specifically, Aspergillus section Nigri, commonly identified as Aspergillus niger through morphological findings, has infrequently been reported as an abdominal SSI pathogen.

An 86-year-old woman with a history of hypertension, chronic kidney disease, and atrial fibrillation who was taking 6 mg of prednisolone daily for rheumatoid arthritis was admitted to our hospital because of sudden abdominal pain. She was diagnosed with sigmoid colon perforation and underwent an open Hartmann operation on the day of admission. Subsequently, a superficial abdominal SSI was detected. Through analysis of the calmodulin gene, Aspergillus welwitschiae, which is classified within the Aspergillus section Nigri, was identified as the responsible pathogen. The minimum inhibitory concentration of voriconazole (VRCZ) was 2 mg/L. Surgical removal of the infected tissue and VRCZ administration was effectively used to treat the infection.

Given the reported low susceptibility of Nigri section species to azoles, identification and drug susceptibility testing of these fungi are highly important.