Cryptococcus neoformans

Ciri dan struktur

Cryptococcus neoformans typically grows as a yeast (unicellular) and replicates by budding. It makes hyphae during mating, and eventually creates basidiospores at the end of the hyphae before producing spores. Under host-relevant conditions, including low glucose, serum, 5% carbon dioxide, and low iron, among others, the cells produce a characteristic polysaccharide capsule. The recognition of C. neoformans in Gram-stained smears of purulent exudates may be hampered by the presence of the large, gelatinous capsule, which apparently prevents definitive staining of the yeast-like cells. In such stained preparations, it may appear either as round cells with Gram-positive granular inclusions impressed upon a pale lavender cytoplasmic background or as Gram-negative lipoid bodies. When grown as a yeast, C. neoformans has a prominent capsule composed mostly of polysaccharides. Under the microscope, the India ink stain is used for easy visualization of the capsule in cerebral spinal fluid. The particles of ink pigment do not enter the capsule that surrounds the spherical yeast cell, resulting in a zone of clearance or "halo" around the cells. This allows for quick and easy identification of C. neoformans. Unusual morphological forms are rarely seen. For identification in tissue, mucicarmine stain provides specific staining of polysaccharide cell wall in C. neoformans. Cryptococcal antigen from cerebrospinal fluid is thought to be the best test for diagnosis of cryptococcal meningitis in terms of sensitivity, though it might be unreliable in HIV-positive patients. The first genome sequence for a strain of C. neoformans (var. neoformans; now C. deneoformans) was published in 2005.

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Rujukan: [1]

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Habitat dan peran ekologis

Cryptococcus neoformans is an encapsulated basidiomycetous yeast belonging to the class Tremellomycetes and an obligate aerobe that can live in both plants and animals. Its teleomorph is a filamentous fungus, formerly referred to Filobasidiella neoformans. In its yeast state, it is often found in bird excrement. It has remarkable genomic plasticity and genetic variability between its strains, making treatment of the disease it causes difficult. In addition, it has been shown to cause disease in apparently immunocompetent hosts, especially in developed countries. Infection with C. neoformans is termed cryptococcosis. Most infections with C. neoformans occur in the lungs, as the fungus enters its host through the respiratory route. Because it is normally a harmless soil fungus, C. neoformans must first adapt to its new environment inside the human body, making several virulent transformations, including the formation of a polysaccharide capsule. The specific factors that enable this transformation involve sensory receptor proteins common to most soil fungi (pH sensors, carbon dioxide sensors, and intracellular iron detectors) which have been adapted to induce C. neoformans cells into rapidly becoming a dangerous, disease-causing organism.

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Rujukan: [1]

Habitat atau konteks temuan

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Substrat

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Peran atau konteks

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Reproduksi

Cryptococcus neoformans typically grows as a yeast (unicellular) and replicates by budding. It makes hyphae during mating, and eventually creates basidiospores at the end of the hyphae before producing spores. Under host-relevant conditions, including low glucose, serum, 5% carbon dioxide, and low iron, among others, the cells produce a characteristic polysaccharide capsule. The recognition of C. neoformans in Gram-stained smears of purulent exudates may be hampered by the presence of the large, gelatinous capsule, which apparently prevents definitive staining of the yeast-like cells. In such stained preparations, it may appear either as round cells with Gram-positive granular inclusions impressed upon a pale lavender cytoplasmic background or as Gram-negative lipoid bodies.

Sebagian uraian ditampilkan dalam bahasa sumber; terjemahannya belum tersedia atau belum lolos pemeriksaan.

Rujukan: [1]

Catatan identitas dan cakupan

• Nama diterima mengikuti Catalogue of Life Base2026-09-11; uraian mempertahankan konsep dan nama sumber aslinya.
• Original geographic, specimen and life-cycle scope retained; source import awaits individual editorial review.
• Impor dan terjemahan otomatis belum diperiksa editorial per profil. Struktur reproduktif yang disebutkan tidak membuktikan seluruh siklus hidup diketahui.
• Pengukuran pada uraian mengikuti spesimen, kultur, dan metode sumber; angka tidak diperluas ke semua populasi.

Melihat dengan konteks

Dokumentasi Cryptococcus neoformans dari Wikimedia Commons. This photomicrograph depicts Cryptococcus neoformans using a light India ink staining preparation. Life-threatening infections caused by the encapsulated fungal pathogen Cryptococcus neoformans have been increasing steadily over the past 10 years because of the onset of AIDS, and the expanded use of immunosuppressive drugs. Identifikasi mengikuti record berkas sumber.

Jenis

Fotografi

Kredit

Photo Credit: Content Providers(s): CDC/Dr. Leanor Haley

Lisensi

Public domain

Sumber media

Buka entri sumber

Gambar menunjukkan objek menurut identifikasi sumber, bukan verifikasi independen spesimen oleh Fungi. Tidak ada skala baru yang ditambahkan.

Sumber profil

1. [1] Cryptococcus neoformans — Wikipedia (en)Bagian sumber: Frozen revision 1373799179
   Tanggal penghimpunan sumber: 2026-10-12
   Teks sumber: CC BY-SA4.0 · Wikipedia contributors
2. [2] Catalogue of Life Base2026-09-11 — Cryptococcus neoformansBagian sumber: ColDP NameUsage.tsv ID ZWQQ; accepted species; source 2073
   Tanggal penghimpunan sumber: 2026-10-12
3. [3] Dokumentasi visual — Cryptococcus neoformansBagian sumber: Individual media record; identification follows the source, not independent determination
   Tanggal penghimpunan sumber: 2026-10-12
   Media sumber: Public domain · Photo Credit: Content Providers(s): CDC/Dr. Leanor Haley