Submitted to: Journal of Clinical Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/7/2011
Publication Date: 6/20/2011
Citation: Hemashettar, B.M., Patil, R.N., O Donnell, K., Padhye, A.A. 2011. Chronic rhino-orbital mucormycosis caused by Mucor irregularis (Rhizomucor variabilis) in India. Journal of Clinical Microbiology. 49(6):2372-2375. Interpretive Summary: This research was conducted to identify and characterize the pathogen responsible for a chronic nasal infection in an 18-year old immunocompetent male from south India. The patient was admitted to the Jawaharlal Nehru Medical College Hospital (Belgaum, India) with a 12-yr history of progressive destruction of the nasal septum, soft and hard palate leading to collapse of the nose bridge. Examination of thin sections of a nasal biopsy revealed broad, non-septate hyphae suggesting the pathogen might be a mold in the fungal order Mucorales. A portion of the biopsy cultured on agar resulted in the growth of several whitish to lemon-yellow colonies on agar plates incubated at 28°C. Microscopic examination suggested the colonies were Mucor-like. DNA sequence data obtained from portions of three genes from the mold. Comparisons of this data with the GenBank database indicated the mold was Rhizomucor variabilis. However, the pathogen is reported in this study as Mucor irregularis because it is nested phylogenetically within Mucor and because it does not form an exclusive group with Rhizomucor based on analyses of the DNA sequence data. This study should be of interest to clinicians treating fungal infections because Mucor and Rhizomucor species may have different susceptibilities to antifungal drugs.
Technical Abstract: We describe a chronic case of rhino-orbital zygomycosis caused by Mucor irregularis, formerly known as Rhizomucor variabilis var. variabilis, a rare mycotic agent in humans. The infection caused progressive destruction of the nasal septum, soft and hard palate, leading to collapse of the nose bridge and an ulcerative gaping hole. The mucoralean mold cultured from a nasal biopsy was determined by multilocus DNA sequence data to be conspecific with M. irregularis.