Photo Quiz: A 52-Year-Old Liver Transplant Patient with Chronic Diarrhea

A 52-year-old male underwent a liver transplant for cirrhosis due to nonalcoholic steatohepatitis. His cytomegalovirus serostatus was donor-negative, recipient-negative, and his Epstein-Barr serostatus was donor-positive, recipient-negative. He did not receive any induction and his posttransplant immunosuppressive regimen consisted of tacrolimus, azathioprine, and a tapering dose of prednisone. He developed subacute diarrhea postoperative day 1 of his transplant, which was felt to be medication-related. Four months after his transplant, he presented to the hospital with worsening diarrhea leading to weakness and a mechanical fall. At this time, he reported ongoing diarrhea since his transplant. Computerized tomography (CT) scans performed as part of an initial trauma evaluation revealed the presence of masses in his nasopharynx, lungs, pleura, and liver as well as generalized abdominal lymphadenopathy and diffuse colonic thickening. He underwent a biopsy of the nasopharyngeal mass, and histopathology showed posttransplant lymphoproliferative disorder. A serum Epstein-Barr viral load was checked and resulted in 60,700 copies/mL. He developed progressive pancytopenia and hyperferritinemia, raising concern for a secondary hemophagocytic lymphohistiocytosis. He was treated with dexamethasone and rituximab, and his other immunosuppressive medications were held. However, despite these interventions, he continued to experience profuse diarrhea, with up to 5 to 6 liters of watery stool per day. A repeat CT scan of his abdomen and pelvis revealed persistent colonic thickening and, consequently, an evaluation for infectious etiologies was undertaken. Molecular Clostridioides difficile toxin assay and a multiplex enteric pathogen panel (for bacterial and viral targets) were performed alongside an enzyme immunoassay for Giardia spp. and Cryptosporidium spp., all of which were negative. A second stool sample was submitted for microscopic examination of ova and parasites. A modified trichrome stain for microsporidia (Fig. 1A) and modified acid-fast stain for coccidian parasites were requested (Fig. 1B).

FIG 1.

Permanent stains performed on a concentrated stool specimen submitted for ova and parasite examination. Magnification was 1000×. (A) modified trichrome stain (for microsporidia). (B) Modified acid-fast stain (for coccidian parasites).

What microbiological phenomenon is observed on the modified trichrome stain? What class of organisms would you be suspicious of based on the characteristics observed in Fig. 1A and B?