Malassezia furfur and Malassezia spp . -Microscopic exam; Culture, Molecular diagnosis (PCR); Species identification (PCR and sequencing).

Information 12/14/09.

Malassezia spp. It is an opportunistic fungus that can be found in healthy individuals, which would be part of the skin microflora, mainly in those with oily skin, for which their involvement is supported on various skin conditions (eg Pytiriasis versicolor and folicultis). In addition it is considered likely their participation in other skin conditions , and is responsible for systemic infections in certain situations. This fungus previously differentiated in two species, Pityrosporum orbiculare and Pirosporum ovale, according to microscopic morphology, and subsequently these two species different forms of a single species were considered: Malassezia furfur.

Until recently only two Malassezia species were admitted: Malassezia furfur, lipophilic (dependent for cultivation of the presence of fat in the culture medium), and Malassezia pachydermatis, no lipophilic (without fat in the culture medium) . Subsequently the number of species was increased, first to seven species, then 11, and 13 are currently recognized species: M. caprae, M. dermatis, M. equine, M. furfur, M. globosa, M. nana, M . obtusa, M. pachydermatis, M. restricta, M. slooffiae, M. sympodialis, M. japonica, and M. yamatoensis.

Of the 13 extant species, all are lipophilic, except M. pachydermatis that can develop in fat - free mass crops. Microscopic examination is very useful in some types of injury where yeast or pseudomycelia focus on skin flakes (eg. In versicolor). Cultivation is slow, especially for some of them, so in IVAMI not recommend it as a diagnostic method. Similarly, based on the results of some biochemical-metabolic tests, phenotypic differentiation is difficult and slow because of the special characteristics of this fungus.

Currently considered the following pathogenic associations:

Malaysia Furfur - widespread infection in neonates hospitalized with low birth weight, receiving intravenous lipid emulsions; Psoriasis.
Malassezia globosa • - Pityriasis versicolor, which correspond to the previous species Pityrosporum orbiculare subsequently considered Malassezia furfur serovar. B.
Restricted Malassezia - seborrheic dermatitis and pitiriásicos states (dandruff), corresponding to the above species Pityrosporum ovale and Malassezia furfur serovar. C.
Malassezia sympodialis - Atopic Dermatitis.
Malassezia pachydermatis - Rara involvement in human infections, except for some outbreaks of sepsis. Its natural hosts are dogs, but have found carrier states in people with dogs.

The involvement of other species in certain clinical processes under study, there are several publications that try to correlate any specific, or more than one species, in processes such as Psoriasis, infant seborrheic dermatitis, atopic dermatitis, folliculitis, onychomycosis, papillomatosis skin confluent reticulated neonatal cephalic pustulosis, lung infections in low birth weight take nourishment intravenous lipid solutions funguemias boxes, ... etc.

Tests in IVAMI:

Microscopic examination to visualize yeast or pseudomycelia in skin scales.
Growing media with special requirements: Not recommended for IVAMI for its slowness.
molecular target for PCR ITS1.
molecular target for PCR ITS1 and sequencing for species identification.

Recommended sample:

Tinea versicolor skin lesions, folliculitis, atopic dermatitis, psoriasis, skin ... .: scraping scales of the affected area, deposited in polypropylene container wide mouth with tight - fitting lid.

Respiratory infections of the newborn (lower respiratory secretions) deposit 1 to 2 mL of liquid sample in a tube or in a sterile container, preferably polypropylene to prevent breakage, containing 3 mL of a universal transport medium.

systemic Ingecciones (fungemia) in newborns or patients undergoing parenteral nutrition infusion solutions lipid: Blood sample obtained in EDTA tube (10 mL).

Preservation and shipment of sample:

Refrigerated (preferred) for less than 2 days.
Frozen: over 2 days.

Delivery term:

Microscopic examination: 24 hours.
molecular target for PCR ITS1: 48 hours.
molecular target for PCR ITS1 and sequencing for species identification: 72 to 96 hours.

Cost of the test: