Mucormycosis in a transplant recipient.

Mucormycosis classically occurs in patients who have uncontrolled diabetes who develop rhinocerebral disease. A fatal case of rhinocerebral infection caused by Rhizopus arrhizus in a 53-year-old man who had received a renal homograft three years previously is reported. Only five similar cases have been documented, all since 1970. Although direct smears of the purulent nasal exudate revealed the presence of numerous Gram-negative bacilli, later identified as Haemophilus influenzae, the diagnosis of mucormycosis was made by demonstrating the typical broad, nonseptate branched hyphae in the necrotic tissue obtained by surgical debridement of the paranasal sinuses. Culture of this material revealed growth of mold-like fungus which, upon direct microscopic examination, showed sporangiophores bearing spherical sporangia arising directly from a cluster of root-like structures of rhizoids. Despite the immediate institution of therapy with amphotericin B postoperatively, the patient died 48 hours later. Subsequently, the Rhizopus isolated was shown to be resistant to both amphotericin B and 5-fluorocytosine. The present case and two others stress the importance of an aggressive diagnostic approach to patients suspected of having mucormycosis, because the usual microbiologic technics are frequently, inexplicably, unsuccessful, and possibly even misleading in this disease.