Scedosporium: Introduction, disease causing, lab diagnosis and treatment

Introduction

Scedosporium apiospermum is an emerging opportunistic filamentous fungus.It is notorious for its high levels of antifungal-resistance and fast growing. Colonies are greyish -white, suede-like to downy with a greyish-black reverse. Numerous single-celled, pale brown, broadly clavate to ovoid conidia, 4-9x 6-10 µm. Conidia arises singly or in small groups on elongate, simple or branched conidiophores or laterally on hyphae as shown above picture.

Two species i.e. Scedosporium apiospermum  and are of medical importance. All isolates of Scedosporium aurantiacum  produce a light yellow diffusible  pigment on potato dextrose agar (PDA) after few days of incubation. Conida and conidiophores of these two species  are similar  in shape and size, and therefore genetic analysis can only distinguish. It falls in risk group 2.

Disease causing

It is an emerging opportunistic fugal pathogen causing diseases in both immunocompromized and immunocompetent  persons. The vast majority of infections are mycetomas and other infectins of the eye , ear, central nervous system, internal organs and more commonly the lungs.

Laboratory Diagnosis

Laboratory diagnosis is useful for identification and isolation of organisms. Most common tests are potassium hydroxide (KOH) mount of spacemen, culture and sensitivity, Lactophenol cotton blue (LPCB) preparation, biochemical test and also if necessary can perform genetic analysis.

Treatment

Anti fungal susceptibility test (AFST) is necessary to perform because of providing selective anti fungal drug to treat this type of fungal etiological agent.

It is notorious for its high levels of antifungal-resistance and thus minimum inhibitory concentration (MIC) test necessary. Drugs are available to treat this pathogen are itraconazole,amphotericin B, voriconazole and posaconazole.

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