Mycology Lecture Notes - Subcutaneous Mycoses

INSTITUTE OF HEALTH TECHNOLOGY, DHAKA Department of Laboratory Medicine BSc in Health Technology (Laboratory) - 1 st Year MYCOLOGY Lecture No. 05 (Subcutaneous Mycoses) By Sk. MIZANUR RAHMAN Lecturer, Mycology MS in Biotechnology & Genetic Engineering (UODA) MS in Microbiology (SUB) S...

INSTITUTE OF HEALTH TECHNOLOGY, DHAKA Department of Laboratory Medicine BSc in Health Technology (Laboratory) - 1 st Year MYCOLOGY Lecture No. 05 (Subcutaneous Mycoses) By Sk. MIZANUR RAHMAN Lecturer, Mycology MS in Biotechnology & Genetic Engineering (UODA) MS in Microbiology (SUB) SUBCUTANEOUS MYCOSES Introduction: Chronic, granulomatous infections of the subcutaneous tissues, usually on an extremity (hands, feet); can extend through the lymphatics or form sinus tracts. Caused by a variety of fungi and bacteria -like fungi that live in the soil. SUBCUTANEOUS MYCOSES Types • Mycetoma • Phaeohyphomycosis • Chromoblastomycosis • Sporotrichosis • Lobomycosis • Rhinosporidiosis MYCETOMA (= Maduromycosis =Madura foot) • Chronic, slowly progressive granulomatous infection of skin & subcutaneous tissues with the involvement of underlying fasciae & bones commonly affecting the extremities . • Reported by Gill from Madurai, S .India . • Maduramycosis or Madura foot . • Tropical & subtropical countries of Asia , Africa, Central & S .America . • Fungi associated with fungal mycetoma are opportunistic. • mycotic mycetoma - usually more common in men (3:1 to 5:1) than in women • usually results from trauma or puncture wounds to feet, legs, arms and hands (usually on the feet) MYCETOMA (= Maduromycosis =Madura foot) MYCETOMA (= Maduromycosis =Madura foot) • Posttraumatic chronic inf. of subcutaneous tissue • Common in tropical climates • Causative agents Saprophytic fungi ( Eumycetoma ) Actinomyces (Actinomycetoma ) MYCETOMA Causative agents • Madurella mycetomatis • Pseudallescheria boydii • Acremonium • Exophiala jeanselmei • Leptosphaeria • Aspergillus Classification of Mycetoma • Based on the causative agent Fungi – Eumycetoma Bacteria ( actinomycetes ) - Actinomycetoma • Based on the colour of grains Bacterial agents – white to yellow grains except Actinomadura pelletieri (red or pink) Fungal agents – black as well as white grains. Colour of grains in Mycetoma of various etiology White to yellow Brown to black Red Nocardia asteroides Madurella mycetomi Actinomadura madurai Nocardia brasiliensis Madurella grisea Actinomadura madurai Phialophora jeanselmei Streptomyces somaliensis Pseudollescheria boydii MYCETOMA Clinical findings Site(s) : Feet , lower extremities, hands Findings : Abscess formation, draining sinuses containing granules Deformities Dissemination : Muscles and bones Mycetoma Sporotrichosis A 60 -year -old woman developed multiple subcutaneous nodules and abscesses on her right hand and forearm 7 days after finger thorn prick Classical C hromoblastomycosis: Fonsecaea pedrosoi Nodulose chromoblastomycosis (Senegal): Fonsecaea pedrosoi MYCETOMA Diagnosis • Clinical findings are nonspecific • Identification of the infecting fungus is difficult • Characteristics of the granule, colony morphology, and physiological tests are used for identification Diagnosis • Laboratory diagnosis - Proper h/o patient - Gross examination of lesion by a microbiologist Specimen – grains or granules - pus / exudates or biopsy Lesions cleaned with antiseptics & the grains collected by pressing the sinus from the periphery. Gross examination of grains – size, shape, texture, colour Madurella mycetomatis causes the majority of the cases with the black grains. It is imperfect dematiaceous mold with brown colonies and diffused honey -colord pigment . Synnemata and conidia Direct Examination • KOH mount – grains Eumycetoma : 2 -6 µ, wide interwoven hyphae with large, swollen cells ( chlamydospores ) at the margin of the lesion. Actinomycetoma : filaments with a diameter of 0.5 - 1µ, coccoid to bacillary forms. If hyphae seen on KOH mount, use special stains. Direct Examination • Gram stain – gram + ve branching filamentous bacteria embedded in the grain material. • Modified Acid fast staining with 1% sulphuric acid – pink colored filamentous bacteria i.e. Nocardia Sps whereas other actinomycetes are non - acid fast. Culture • Different sets of media – both possibilities of fungi & bacteria . • When Actinomycetoma is suspected on direct examination - wash grains several times with NS & then inoculate on SDA without antibiotics. • When Eumycetoma is suspected – wash grains several times in NS with antibiotics( Pn ) & inoculate it on SDA with antibiotics. - incubated at 25 ° & 37 ° C