Geotricum candidum: Introduction, Pathogenecity, Laboratory Diagnosis

Geotricum candidum: Introduction, Pathogenecity, Laboratory Diagnosis and Treatment

Geotricum on SDA

Geotricum candidum on SDA as shown above picture. Colony characteristics on SDA are fast-growing, flat, white to cream, dry, and finely suede-like with no reverse pigment as shown above picture.

Geotrichum candidum

Geotricum candidum is an extremely common fungus and worldwide in distribution. It is normal human flora and was first described in 1809 by Johann Heinrich Friedrich Link and isolated from sputum and feces. Geotricum candidum showing arthroconidium in LPCB mount as shown above picture. Hyphae are hyaline, septate, branched, and break up into chains of hyaline, smooth, one-celled, subglobose to cylindrical arthroconidia. They are 6-12× 3-6 µm in size. They are released by the separation of a double septum.

Scientific classification of Geotricum

(Described by Link ex Persoon in 1822)

Kingdom: Fungi
Phylum: Ascomycota
Subphylum: Ascomycotina
Class: Saccharomycetes
Order: Saccharomycetales
Family: Endomycetaceae
Genus: Geotricum
Species: G. candidum

Note: The genus, Geotricum includes several species among them medically important species are Geotricum candidum and Geotricum capitatum.

Risk group: It comes in risk group 1 organism.

Pathogenicity

Geotrichosis is a fungal disease and its causative agent Geotricum candidum. The most important risk factor for invasive fungal infection related to Geotrichum is severe immunosuppression. Its involvement is especially in hematological malignancies as acute leukemia, associated with profound and prolonged neutropenia. Fungemia is very common, often with deep organ involvement like lung, liver, spleen, and central nervous system. Its involvement is also in skin and mucous membranes lesions.

It can cause the following infections-

Pulmonary infection ( the most common)
Bronchial infection
Oral infection
Vaginal
Cutaneous and
Alimentary infection

Mortality rate: Mortality associated with Geotricum-related infections is high, ranging from 57% to 80%.

Laboratory Diagnosis of Geotricum

Specimen: It depends on the nature of infection involvement.

KOH mount
Culture
LPCB preparation
Physiological tests ( fermentation and assimilation of various carbohydrates)
Histopathological examination: Septate hyphae (3-6 µm wide) and rectangular to oval arthroconidia are observable in tissues infected with Geotricum.
PCR test

Treatment of Geotrichum

There is no optimal treatment for Geotricum infections.

Following antifungal agents are applicable for antifungal susceptibility testing-

Fluconazole

Intraconazole

Voriconazole

Amphotericin B and

Flucytosine.

But according to existing data guidelines recommend amphotericin B with or without co-administered flucytosine or with voriconazole showing well in vitro susceptibility.

Keynotes

Geotricum is different from Trichosporon is due to lacking ability of to produce blastoconidia.
Distinguishing features of G. candidum from G. capitatum is as follows-

G. candidum G. capitatum

Risk group 1 organism Risk group 2
Cylindrical arthroconidia Rectangular arthroconidia
Ferment trehalose Can not ferment trehalose
It does not assimilate D-xylose. It assimilates D-xylose.

universe84a