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Journal of Clinical Microbiology, September 2005, p. 4766-4772, Vol. 43, No. 9
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.9.4766-4772.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Dual Infections with Pigmented and Albino Strains of Cryptococcus neoformans in Patients with or without Human Immunodeficiency Virus Infection in India

Piyali Mandal,¹ Uma Banerjee,¹ Arturo Casadevall,^2,3 and Joshua D. Nosanchuk^2*

Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India,¹ Division of Infectious Diseases, Departments of Medicine,² Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York³

Received 19 May 2005/ Returned for modification 2 June 2005/ Accepted 9 June 2005

Cryptococcus neoformans is an encapsulated yeast-like fungus of worldwide distribution. Melanin production is an important virulence factor of C. neoformans. We report the identification of distinct cryptococcal isolates with either pigmented or white colony phenotypes on L-dihydroxyphenylalanine agar plates in three patients who presented with meningitis to the All India Institute of Medical Sciences in India. Two of the patients were also infected with human immunodeficiency virus. Biochemical studies, India ink analysis, immunofluorescence with antibodies specific to capsular antigen, and serotyping confirmed that the melanotic and albino strains were C. neoformans serotypes A and D, respectively. Genotyping with M13 and [GACA]4 primers revealed that all the C. neoformans isolates were genetically different. The CNLAC1 gene associated with melanin production was identified in all the strains by PCR. Standard MIC testing revealed that the strains had similar susceptibilities to amphotericin B, but time-kill assays with the antifungal showed reduced susceptibility in melanin-producing strains. Infection studies with A/Jcr mice showed that the melanin-lacking yeast were less virulent than melanin-producing isolates. These findings indicate that these patients had dual infections with pigmented and albino strains of C. neoformans that were phenotypically and biologically different. Continued surveillance of primary isolates from patients with cryptococcosis by analyzing phenotypic differences and by molecular methods may reveal that mixed infections occur more commonly than is currently realized.

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* Corresponding author. Mailing address: Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461. Phone: (718) 430-3766. Fax: (718) 430-8968. E-mail: nosanchu{at}aecom.yu.edu.

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Journal of Clinical Microbiology, September 2005, p. 4766-4772, Vol. 43, No. 9
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.9.4766-4772.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

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