Microsporum persicolor: Introduction, Pathogenecity, Laboratory Diagnosis and Treatment

Microsporum persicolor in LPCB mount has  microconidia. Microconidia  are abundant, spherical to pyriform where as macroconidia  thin walled, cigar shaped , four to seven celled  having size of 40-60 × 6-8 µm (rarely produced)   lacking as shown above image.

Microsporum persicolor

Microsporum persicolor in LPCB mount has microconidia. Microconidia are abundant, spherical to pyriform whereas macroconidia are thin-walled, cigar-shaped, four to seven celled having sizes of 40-60 × 6-8 µm (rarely produced)   lacking as shown above image.

Colony characteristics on SDA are generally flat, white to pinkish in color, with a suede-like to granular texture and peripheral fringe.

Risk group: It comes under risk group 2.

Scientific classification

Kingdom: Fungi

Division: Deuteromycota

Class: Eurotiomycetes

Order: Onygenales

Family: Arthrodermataceae

Genus: Microsporum

Species: Microsporum persicolor

Note: It is also referred to as Trichophyton persicolor, , Ctenomyces persicolor, Sabouraudites persicolor or Microides persicolor, and displays a perfect sexual form called Nannizia persicolor.

Pathogenicity

It is one of the genera of dermatophytes. It is a zoophilic fungus often occurring as a saprophyte on voles and bats. It rarely causes tinea corporis in humans. It produces hair perforations in vitro whereas not invade hair in vivo. Human dermatophytosis due to Microsporum persicolor mostly affects young women. It represents 2 to 3% of the zoophilic dermatophytosis cases in humans.

Laboratory Diagnosis

Specimens: Scrapings, smears, Wood’s light examination, trichogram, and  KOH mount as well as fungal culture from hairs, scales, and crusts taken from the lesions.

Punch biopsy: For hematoxylin and eosin and periodic acid-Schiff stains

KOH mount: Presence of fungal elements like hyaline septate branching mycelium and arthroconidia

Culture: Inoculation of the specimen into SDA or dermatophyte test medium( DTM) and incubation up to 2-4 weeks at room temperature. Colony characteristics are similar to generally flat, white to pinkish in color, with a suede-like to granular texture and peripheral fringe.

LPCB preparation: High numbers of spherical to pyriform microconidia and rare cases of thin-walled, cigar-shaped, four to seven celled macroconidia may also be found.

PCR test:  It uses for confirmation at the molecular level.

Treatment

There is lacking information on proper treatment in humans but in animals (dogs) standard anti-fungal drugs recommended are griseofulvin, ketoconazole, and enilconazole.

References

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3058648/
  2. https://jamanetwork.com/journals/jamadermatology/article-abstract/533489
  3. https://watermark.silverchair.com/
  4. https://www.researchgate.net/publication/266886691_The_First_Case_of_Microsporum_persicolor_Infection
  5. https://www.phe-culturecollections.org.uk/products/fungi/detail.jsp?refId=NCPF+0357&collection=ncpf
  6. Description of Medical Fungi by David Ellis, Stephen Davis, Helen Alexiou, Rosemary Handke, Robin Bartley, 2nd Edn
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