Furthermore, P. boydii grains and hyphae should be cultured and observed microscopically after staining with H&E, periodic acid–Schiff stain, Tissue Gram or Grocotts methenamine silver stain. A radiological diagnosis may be helpful in elucidating the extent of the disease in terms of bone and soft tissue involvement. Scedosporium-caused eumycetomas have been found to have thick-walled cavities and grains appearing as hyperreflective echoes on scans, while actinomycetomas show fine echoes at the bottom of cavities.Direct detection is possible in samples histochemically stained in 20% KOH followed by fluorescence microscopy with antibody. The characteristic shape, texture and colour of tissues can help identify S. apiospermum grains, which are often surrounded by an eosinophilic zone. Histopathologically, hyalohyphomycotic fungi like Scedosporium spp., Aspergillus spp., Fusarium spp. and Petriella spp. are similar in that they show septation of hyphae at regular intervals, have dichotomous branching and invade blood vessels. However, Scedosporium presents more irregular branching, sometimes with terminal or intercalary chlamydospores. In serum, Scedosporium infections can be detected by counterimmunoelectrophoresis. Molecular diagnostics appear to be promising in complementing current conventional diagnostic methods.Culture detection is accomplished by rinsing "grains" in 70% ethanol and sterile saline solution to avoid bacterial contamination prior to inoculation on growth medium. Selection of Scedosporium growth can be achieved on Leonians agar supplemented with 10 g/mL benomyl, or on media containing cycloheximide or amphotericin B. Optimal incubation is at a temperature of 25–35 °C (77–95 °F). Treatment
Pseudallescheria boydii is resistant to amphotericin B and nearly all other antifungal drugs.
Infections in the CNS, which are rare, present as neutrophilic meningitis or multiple brain abscesses and have a mortality rate of up to 75%. Infections have also been observed in animals, notably corneal infection, abdominal mycetoma and disseminated infections in dogs and horses. Transient colonization is more likely than disease. However, invasive pseudoallescheriasis can be found in patients with prolonged neutropenia, high-dose corticosteroid therapy and allotransplantation of bone marrow. Pseudallescheria boydii has also been implicated in pneumonia subsequent to near-drowning events with infection developing anywhere between a few weeks to several months after exposure yielding high mortality. Dissemination of the organism to the central nervous system has been observed in some cases. This species is also known as a non-invasive colonist of the external ear and airways of patients with poor lung or sinus clearance, and the first documented case of human pseudallescheriasis involved the ear canal. It has also been implicated in infection of joints following traumatic injury, and these infections can progress to osteomyelitis. Infections of the skin and cornea have also been reported. Typical host-related risk factors for infection include lymphopenia, steroid treatment, serum albumin levels of < 3 mg/dL and neutropenia. Diagnosis
Detection and diagnosis of S. apiospermum is possible through isolation of the fungus in culture or through cytology and histopathology in the tissues of diseased individuals. In mycetoma-type infections, a confluence of symptoms is necessary for diagnosis, including tumefaction, draining sinuses and extrusion of grains.