Clinical Mycology 6.pdf

Subcutaneous Mycoses DR. WIFAG RABIH Subcutaneous Mycoses Mycetoma ( involving cutaneous and subcutaneous tissues, and bone; usually occurring on the foot or hand). clinical syndrome of localized, deforming, swollen lesions and sinuses Etiologic agents may be bacterial or fungi. Chromoblastomycosis...

Subcutaneous Mycoses DR. WIFAG RABIH Subcutaneous Mycoses Mycetoma ( involving cutaneous and subcutaneous tissues, and bone; usually occurring on the foot or hand). clinical syndrome of localized, deforming, swollen lesions and sinuses Etiologic agents may be bacterial or fungi. Chromoblastomycosis (subcutaneous and cutaneous tissues of the hands and feet). Phaeohyphomycosis (face, cornea of eye, subcutaneous and cutaneous part of skin, occasionally cerebral and systemic) Sporotrichosis (cutaneous and subcutaneous tissues and adjacent lymphatics that suppurate, ulcerate and drain) Lobomycosis (subcutaneous and cut. tissues over different parts of body). Rhinosporidiosis (nasal cavities, mucocutaneous tissue - rarely it does effect the vagina, penis, anus, ears, and throat region) Mycetoma was first reported in the mid-19th century in Madurai, India, and was initially called Madura’s foot. The causative organisms of mycetoma are distributed worldwide but are endemic in tropical and subtropical areas in the so-called 'Mycetoma belt' Mycetoma One potential causal agent can be Pseudallescheria boydii, a soil/waterinhabiting fungus with worldwide distribution. However other fungi can be involved.  It usually involves the subcutaneous tissue after a traumatic inoculation of the causative organism.  Mycetoma may be caused by true fungi or by higher bacteria and hence it is usually classified into eumycetoma and actinomycetoma respectively. Mycetoma is caused by: Higher bacteria Actinomycetoma True Fungi Eumycetoma Mycetoma is caused by common saprotrophs found in the soil and on thorny shrubs in semi-desert climates. Some common causative agents are Madurella mycetomatis (fungus) Nocardia brasiliensis (bacteria) Actinomadure madura (bacteria) Streptomyces somaliensis (bacteria) Actinomadura pelletieri (bacteria) It is important to know whether the mycetoma is fungal or actinomycete origin, because actinomycosis infections usually respond to treatment with antibiotics and sulphonamides, whereas fungal infections are resistant to antimicrobials. Affected area: Foot, which is commonly affected (Madura’s foot). Knee, arm, scalp, leg, head, neck, thigh, perineum, and wall of the chest. Complications: Osteomyelitis, secondary infection, and deformity. MYCETOMA- CHARACTERS The formation of sinus tracts characterizes mycetoma. The sinuses usually discharge purulent and seropurulent exudate-containing grains. It may spread to involve the skin and the deep structures resulting in destruction, deformity and loss of function. Found in plant materials, eg wood or thorns and soil Localized infections. No association with any underlying disease. This infection is endemic in Africa, India, and Central and South America. Mycetoma Pathogenesis The disease is usually acquired while performing agricultural work ti dna , generally afflicts men between 20 and 40 years old. Infection usually involves an open area or break in the skin. The disease is characterized by a yogurt-like discharge upon maturation of the infection. Infections normally start in the foot or hand and travel up the leg or arm. starts out as tumor-like to subcutaneous swelling ruptures near the surface; infects deeper tissues including subcutaneous tissues and ligaments (tendons, muscles, and bone) Laboratory diagnosis Direct examination of grains Culture Histopathology Serology PCR (polymerase chain reaction) Imaging can be used to assess the depth of infection ◦ Plain X-ray, Ultrasound scan, Computed tomography (CT), and Nuclear magnetic resonance imaging (MRI). Clinical Material: Tissue biopsy or excised sinus, serosanguinous fluid containing granules that vary in size, color, and degree of hardness, depending on the aetiologic species. Direct microscopic: Actinomycetoma: Thin branching filaments Gram positive Acid fast in case of Nocardia Eumycetoma: Broad septate hyphae Some time with chlamydosopres Culture: Clinical specimens should be inoculated onto primary isolation media, like Sabouraud's dextrose agar. This is required for confirmation of the diagnosis. Wash in saline with antibiotics Culture on SDA with antibiotics Incubate at 37° C aerobically for 4-6 weeks In another sample, wash in saline without antibiotics Culture on LJ or BHIA Incubate at 37° C aerobically for 4-6 weeks Mycetoma-Treatment lesions of mycetoma seldom heal spontaneously. disease is chronic and may continue for 40-50 years. P. boydii is resistant to all systemically useful drugs, including amphotericin. ketoconazole appears to be ineffective in clinical trials intravenous miconazole. surgery and removal of tumor ( if small it is encapsulated if larger amputation may be required) Combining miconazole and surgery may prove useful in effectively treating the disease. Antifungal drugs used to treat mycetoma are: only 25-35% effective administered for 12 months unsafe with many side effects too expensive for people with the disease not available in areas where the disease is found Chromoblastomycosis Disease is one of hyperplasia, characterized by the formation of verrucoid (rough), warty, cutaneous nodules, which may be raised 1-3 cm above the skin surface. The roughened, irregular, vegetations often resembles the florets of cauliflower occurs rarely in animals (such as, horses, cats, dogs, and frogs) soil-inhabiting fungi susceptibility enhanced by wearing sandals. found almost exclusively in laborers. enters hand or feet after trauma. found primarily in the tropics or subtropics. dull red or violet color on skin may resemble a ringworm lesion pruritus (itchiness) and papules may develop. fungus gets under the skin (produces bumps). bumps may block lymphatic system and cause elephantiasis. sometimes bacterial infection may enter and cause a secondary infection. rarely this fungus spreads to other areas of the subcutaneous tissue. potentially may spread to brain (life-threatening in that case) Lobomycosis Lobomycosis is a chronic, localized, subepidermal infection characterized by the presence of keloidal, nodular lesions or sometimes by vegetating crusty plaques and tumors. The lesions contain masses of spheroidal, yeast-like organisms tentatively referred to as Loboa loboi. There is no systemic spread. The disease has been found in humans and dolphins and is restricted to the Amazon Valley in Brazil. Prevention & Control Mycetoma is not a notifiable disease (a disease required by law to be reported) and a global surveillance system is still being developed. There are no control programmes for mycetoma yet, except for Sudan. Preventing infection is difficult, but people living in or travelling to endemic areas should be advised not to walk barefooted. MRC In Sudan, an estimated 63,825 individuals have suffered from mycetoma since 1991. In 1991, The Mycetoma Research Centre (MRC) was established under the umbrella of the University of Khartoum. It was set up at Soba University Hospital. The centre is recognised globally as a world leader and an authoritative advisor in mycetoma management and research. It is a WHO Collaborating Centre on Mycetoma. The Government of Sudan and WHO convened the First International Training Workshop on Mycetoma in Khartoum on 10–14 February 2019. Drawing on the expertise of the Mycetoma Research Centre in Khartoum, the workshop attended by approximately 70 health staff from many mycetoma-endemic countries. It provided a unique opportunity to share experiences and standardize practices relating to diagnosis, treatment and surveillance.