Zygomycosis by Rhizopus species – a very rare angioinvasive mycosis: report of three cases

Introduction

Zygomycosis caused by Rhizopus species (Rhsp) 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, immune defects or metabolic disturbances like diabetic ketoacidosis. Rhizopus infections are characterized by angioinvasive growth, necroses of infected tissue and perineural invasion. The invasion of blood vessels is remarkable for a fungal infection. The mortality of zygomycosis is very high, especially for disseminated disease and if immunosuppression cannot be corrected.

Patients

Patient 1 (female, 73 years): Delayed clinical course according to infection of a hip-TEP and a femoropopliteal bypass of the right leg, eventual exarticulation of the right hip joint, pseudomonas pneumonia, severe sepsis caused by staphylococci, acute respiratory distress syndrome, acute renal failure and multiple use of antibiotics. Subsequent detection of Rhsp in the bronchoalveolar lavage and treatment with amphotericin B for this reason. Patient 2 (male, 68 years): 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. Rhsp 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 because of Candidemia in addition to zygomycosis. The further course was delayed by several septic phases. Patient 3 (male, 72 years): An insignificant past medical history with appendectomy, secondary wound-healing; hypertension, hyperlipoproteinemia. No hint for an immune defect. Operation because of adhesion ilueus, postoperative severe septic shock owing to peritonitis. After 1 month of intensive care therapy with multiple lavages and antibiotics microbiologically proven abdominal infection with Rhsp. All patients died later in spite of all efforts.

Discussion

The very rarely seen zygomycosis caused by Rhsp developed in patient 1 and patient 2 owing to immunosuppression – in the first, iatrogenic induced by immunosuppressive drugs after organ transplantation; in the second as a result of previous immunosuppression and prolonged severe sepsis. Zygomycosis of the third patient developed because of prolonged severe septic shock without a hint of a immune deficit before.

In comparison with other mycoses, treatment of Rhsp infections remains difficult. The affinity to blood vessels, where the fungi multiply and their feature of vascular invasion with thrombosis and infarction are complicating therapeutic efforts, which should include surgical resection whenever possible and amphotericin B.