Dalia Kamal Eldien Mohammed

 The main subcutaneous fungal infections include:  Mycetoma  Chromoblastomycosis  Sporotrichosis  Lobomycosis  Rhinosporidiosis  Subcutaneous zygomycosis  Subcutaneous phaeohyphomycosis.

 The zygomycetes are a relatively small group in the fungi kingdom and belong to the Phylum Zygomycota.  They include the familiar bread mold Rhizopus stolonifer, which rapidly propagates on the surfaces of breads, fruits, and vegetables.  They are mostly terrestrial in habitat, living in soil or on plants and animals.

 The Zygomycetes, a class of fungi with a ubiquitous and worldwide distribution that is characterized by aseptate hyphae, fast growing, saprophytic fungi.  The fungi usually reproduce asexually by producing sporangio spores.  When spores land on a suitable substrate, they germinate and produce a new mycelium.  Sexual reproduction starts when conditions become unfavorable, produce the zygospore

 The term zygomycosis describes in the broadest sense any infection due to a member of the Zygomycetes.  Zygomycosis is the third most common invasive fungal infection after candidiasis and aspergillosis  invasive fungal infections common in both immunocompetent and immunocompromised individuals

This class of fungi encompasses two orders:  Mucorales  Entomophthorales

 The order Mucorales include several genera  Rhizopus  Rhizomucor  Mucor  Absidia  involved in rhinocerebral, pulmonary, cutaneous, gastrointestinal and other less frequent infections in immunocompetent and immunocompromised individuals, and is characterized by a tendency to disseminate  Mucormycosis is the correct term for infections due to fungi of this order.  The term zygomycosis is used to describe any invasive infection due to zygomycetes, although it is frequently used interchangeably with the term mucormycosis

 The order Entomophthorales include  Conidiobolus  Basiodobolus spp  Subcutaneous zygomycosis, which is typically seen in children and adolescents, results from infection with Basidiobolus haptosporus.  It first develops as a localized lesion, usually on the thighs or buttocks, and it spreads slowly to form a hard, painless, non-pitting mass involving the cutaneous and subcutaneous tissues. The mass is shiny, but may later become ulcerated.

 The symptoms depend on where in the body the fungus is growing.  Mucormycosis most commonly affects the sinuses or lungs.  Symptoms of sinus infections include fever, headache, and sinus pain. Lung infections with the fungus can cause fever and cough.  Skin infections can develop after the fungus enters through a break in the skin caused by surgery, burns, or trauma. A skin infection can look like blisters or ulcers, and the infected tissue may turn black. Other symptoms of a skin infection include fever and tenderness pain, heat, excessive redness, or swelling around a wound.  If the infection is not treated quickly, the fungus can spread throughout the body, and the infection is often fatal.

 Portals of entry of zygomycetes are usually the lungs, skin, and gastrointestinal tract.  These rare yet serious and potentially life - threatening fungal infections, usually affect the face or oropharyngeal(nose/mouth) cavity, lungs, gastrointestinal tract, skin, or less commonly other organ systems.  These types of infections are also common after natural disasters, such as tornadoes  A characteristic property of zygomycetes is their tendency to invade blood vessels and to cause thrombosis—processes that result in subsequent necrosis of involved tissues.

Risk factors associated with zygomycosis include:  Prolonged neutropenia  Use of corticosteroids  Solid organ or haematopoietic stem cell transplantation  AIDS  Poorly controlled diabetes mellitus  Burns& wounds  Malnutrition  Extremes of age  Intravenous drug

Specimen:  Skin scrapings from cutaneous lesions  sputum and needle biopsies from pulmonary lesions  Nasal discharges, scrapings and aspirates from Sinuses in patients with rhinocerebral lesions  Biopsy tissue from patients with gastrointestinal and/or disseminated disease.

Direct Microscopy:  10% KOH & Parker ink or Calcofluor mounts  Tissue sections should be stained with H&E.  Results: Examine specimens for broad, infrequently septate, thin-walled hyphae  As a rule, a positive direct microscopy, especially from a sterile site, should be considered significant.

Culture:  Inoculate specimens onto Sabouraud's dextrose agar.  Most zygomycetes are sensitive to cycloheximide (actidione). Colonial morphology:  Look for fast growing, white to grey or brownish, downy colonies. Serology:  some laboratories have developed ELISA tests for the detection of antibodies to Zygomycetes.

 Treatment consists of prompt and intensive antifungal drug therapy and surgery to remove the infected tissue.  The prognosis varies vastly depending upon an individual patient's circumstances.

 Source: Boundless. “Zygomycetes.” Boundless Microbiology. Boundless, 03 Jul Retrieved 08 Dec. 2014from  Kwon-Chung KJ and JE Bennett Medical Mycology Lea & Febiger.