Infectious Disease Compendium

Rhizopus

Microbiology

A mould, a zygomyces; one of the causes of mucormycosis. Rhizopus caespitosus, Rhizopus delemari, Rhizopus homothallicus, Rhizopus microsporus, Rhizopus oryzae, Rhizopus reflexus, Rhizopus schipperae, Rhizopus stolonifer (black bread mold).

Epidemiologic Risks

Environmental, it lives in decaying vegetable matter and soon to be decaying patients. Desferoximine is a risk factor in dialysis patients.

There was an nosocomial outbreak from hopsital linens (PubMed)

Syndromes

Invasive disease, both local (esp lung) and disseminated in the profoundly immunoincompetent.

Important variations:

- Skin disease, especially in burn patients. Also after environmental trauma.

- Invasive pneumonia: especially in patients with hematologic malignancies and on steroids.

- Rhinocerebral: in diabetic ketoacidosis and patients with hematologic malignancies and on steroids. It invades along the muscle of the eyes into the brain. Look for a fixed eye and/or unilateral proptosis. A real emergency if found.

Treatment

Debride if at all possible. Amphotericin B has been the treatment of choice, but depending on the species, posaconazole looks promising in vitro (PubMed). My one cure was with posaconazole in the patient who could not be debrided (lung/sternum infection) but his cancer did go into remission, so I do not know how much was from the antibiotic. I would still rely on debridement more than antibiotics.

There was one salvage with isavuconazole (PubMed).

Notes

R. microsporus var. oligosporus is used to make tempeh, a fermented food derived from soybeans.

R. oryzae is used in the production of alcoholic beverages in parts of Asia and Africa.

Rhizopus stolonifer (black bread mold) causes fruit rot on strawberry, tomato, and sweet potato and used in commercial production of fumaric acid and cortisone (WikiPedia).

Last Update: 04/05/18.