Mucor circinelloides Was Identified by Molecular Methods as a Cause of Primary Cutaneous Zygomycosis

Abstract

A case of primary cutaneous zygomycosis caused by Mucor circinelloides is described. Histopathology showed typical hyphae along with chlamydospores. The isolate was identified by molecular and phenotypic methods. The utility of sequence analysis of the internal transcribed spacer region is highlighted; however, further studies are needed to assess species genetic heterogeneity. CASE REPORTA 90-year-old male presented to his primary-care physician with fever, fatigue, and lower-right-leg cellulitis following trauma to the leg. The trauma, which occurred about 1 month prior to presentation, was described by the patient as being "struck by a shrub branch while trimming brush." He had a 2-year history of progressive pancytopenia subsequently diagnosed as myelodysplastic syndrome (MDS) and a 20-year history of diabetes mellitus type II controlled by insulin injections.On physical examination, the temperature was 38°C, and laboratory examination showed pancytopenia with an absolute neutrophil count of 1.0 ϫ 10 3 per mm 3 (normal range, 1.3 ϫ 10 3 to 7.5 ϫ 10 3 per mm 3 ) and hyperglycemia with a serum glucose level of 525 mg per dl (normal range, 70 to 125 mg per dl). He was hospitalized at the Nebraska Medical Center and started on filgrastim (Neupogen; Amgen, Inc., Thousand Oaks, CA) to improve neutropenia and on insulin to control the serum glucose level. Intravenous ceftriaxone and ciprofloxacin were given for the lower-right-leg skin/soft tissue infection. The patient was discharged on day 7 post-primary admission (PPA) with improvement of the leg cellulitis.A follow-up exam on day 14 PPA showed progression of the leg wound, now with a black eschar developing. The patient was readmitted to the hospital with neutropenia (absolute neutrophil cell count, 0.9 ϫ 10 3 per mm 3 ) and hyperglycemia (serum glucose level, 1,160 mg per dl). He was taken to the operating room for debridement of the wound, and tissue was submitted to the hospital clinical microbiology laboratory for bacterial and fungal cultures. The results of a histopathological examination of this tissue were reported as "hemorrhage and extensive necrosis, focal formation of granulation tissue, and numerous invasive fungal organisms (septate hyphae and thick-walled yeast forms)" (Fig. 1). Based on a diagnosis of an invasive fungal (mold) infection, liposomal amphotericin B (AMB) at 5 mg per kg of body weight per day (Abelcet; ENZON Pharmaceuticals, Piscataway, NJ) was begun (day 16 PPA). A fungus grew within 4 days on Sabouraud dextrose (Emmons) agar (Remel Labs, Lenexa, KS) but did not grow on Mycobiotic agar (Remel Labs) after incubation at 30°C. The isolate, which was morphologically identified as a Mucor species, was subsequently sent to the Molecular Mycology Laboratory located at the University of Nebraska Medical Center (UNMC) for species identification. A DNA sequence of the isolate obtained from the internal transcribed spacer (ITS) regions of the rRNA gene was submitted for a BLAST search of the GenBank database (National Center for Biotechnology...

Spectrum of Zygomycete Species Identified in Clinically Significant Specimens in the United States

“…The molecular identification of clinical zygomycetes using the ITS region has been successfully used in recent years (11,12,19,29,36,37,39). However, a BLAST search can constitute an important limitation of such procedures when comparisons are made with inaccurate sequence data (5).…”

Mucor circinelloides as a Cause of Invasive Maxillofacial Zygomycosis: an Emerging Dimorphic Pathogen with Reduced Susceptibility to Posaconazole

“…Even the identification of the isolates to the species level by morphology alone may not be reliable (19). To overcome this limitation, molecular techniques are now being increasingly applied to identify zygomycetes in grown cultures (15,39). Consistent with this approach, we identified our isolate by DNA sequencing of rDNA, thus validating the morphological/physiologic identification features, such as the ability to grow at 37°C, the presence of intercalary and terminal chlamydospores forming successively in chains, the ability to undergo mold-yeast conversion in BHI broth at 37°C, producing unipolar, bipolar, and multipolar budding forms, and the presence of circinate conidiophores-a hallmark of its morphological identification (22).…”

“…Six of the cases with cutaneous or subcutaneous involvement were either known or suspected to have sustained trauma (Table 1). Hematological malignancy was the underlying disease in four cases (acute myelocytic leukemia and myelodysplastic syndrome in two patients each) (6,12,15,31), one had multiple underlying conditions (insulin-dependent diabetes mellitus with metabolic acidosis, alcoholism, cirrhosis, and corticosteroid treatment) (24), and one had short gut syndrome with multiple surgical interventions (7). Two of the patients had no recognizable underlying condition (11a, 40).…”

ZIGOMICOSIS CUTANEA PRIMARIA POR Rhyzopus oryzae EN UNA NIÑA CON LEUCEMIA LINFOBLASTICA AGUDA TIPO B

“…Aunque estas herramientas pueden ser útiles en los estudios epidemiológicos de brotes de zigomicosis, se conoce mal su rendimiento en el diagnóstico primario (10,11).…”