[Pulmonary zygomycosis--a rare angioinvasive fungal infection]

Zygomycosis caused by Rhizopus species is an aggressive and rapidly progressive opportunistic fungal infection in immunocompromised patients. It comprises mucocutaneous, rhinocerebral, pulmonary, urological and disseminated infections. Predisposing factors are immunosuppression owing to severe diseases, immunological defects or metabolic disturbances like diabetic ketoacidosis. Rhizopus infections are characterized by angioinvasive growth, necroses of infected tissue and perineural invasion. The histopathologic demonstrable invasion of blood vessels is remarkable for a fungal infection. The mortality of zygomycosis is very high, especially for disseminated disease and when immunosuppression cannot be corrected. We report about two cases of pulmonary zygomycosis, caused by Rhizopus spp.: patient 1, female 73 years old: Delayed clinical course according to hip arthroplasty infection and infection of a femoropopliteal bypass of the right leg, eventually exarticulation of the right hip joint, Pseudomonas pneumonia, severe sepsis caused by staphylococci, acute respiratory distress syndrome (ARDs), acute renal failure and multiple use of antibiotics. Subsequently detection of Rhizopus spp. in the bronchoalveolar lavage and treatment with amphotericin B for this reason. Patient 2, male 68 years old: transplantation of kidney in past medical history, presenting with acute renal failure and with quite a few infections before. In the sequel development of abscessing pneumonia on the right side with a pleural empyema. Rhizopus spp. were detected by microbiological testing in the empyema fluid. These findings required surgical intervention, resection of the lower lobe of the right lung and within the same operation of the renal graft because of rejection. The patient was treated with caspofungin. The further course was delayed by several septic phases. Both patients died later on in spite of all efforts. The very rarely seen pulmonary zygomycosis caused by infection with Rhizopus spp. developed in both patients owing to immunosuppression, in one patient iatrogenically induced by immunosuppressive drugs after organ transplantation, in the other as a result of prolonged severe sepsis. In comparison with other mycoses treatment of Rhizopus infections remains difficult. The affinity to blood vessels, where the fungi multiply, and their feature of vascular invasion with thrombosis and infarction complicate therapeutic efforts.