DEPARTMENT OF BIOLOGICAL SCIENCES REDEEMER’S UNIVERSITY MCB 313 PATHOGENIC MYCOLOGY DURUGBO ERNEST UZODIMMA (Ph.D.) COURSE OUTLINE 1. Introduction 2. Structure, reproduction and classification of pathogenic Fungi Eg. Aspergillus, Trichphyton spp., Tinea spp.,Yeasts 3.Superficial systematic mycoses and antimycoses 4. Fungal infections ( Candidiasis , Histoplasmosis etc) 5. Laboratory methods of study 5. Pathology and immunology 6. Cultivation techniques in Mycology Structure, Reproduction and Classification of Pathogenic Fungi About 30% of the 100,000 known species of Fungi make a living as parasites, or pathogens , mostly of plants. E. g Cryphonectria parasitica, the Ascomycete fungus causes chestnut blight. Fusarium circinatum causes pith pine canker a diseae that threatens pine worldwide. Puccinia graminis causes black stem rust of wheat. Some of the fungi that attack food crops are toxic to humans for example certain species of the ascomycete mold Aspergillus contaminate improperly stored grain and peanuts by secreting aflatoxins which are carcinogenic. The ascomycete Claviceps purpurea which grows on rye plants forming purple structures called ergots. If diseased rye is milled into flour and consumed it causes ergotism, a condition characterized by gangrene, nervous spasms, burning sensations, hallucinations, and temporary insanity. An epidemic of this around 944 C.E, killed more than 40,000 people in France. Animals are much less susceptible to parasitic fungi than plants. Only about 50 species of fungi are known to parasitize humans and animals . Such fungal infections are mycosis . Skin mycoses includes ringworm. The ascomycetes that causes ringworm can infect almost any skin surface. Most commonly, they grow on the feet, causing the intense itching and blisters known as athlete ’s foot. These diseases are highly contagious but can be treated with fungicidal lotions and powders. Systemic mycoses spread through the body and usually cause very serious illnesses. They are typically caused by inhaled spores eg coccidioidomycosis is a systemic mycosis that produces symptoms similar to tuberculosis in the lungs. Some mycosis are opportunistic occurring only when there is a change in the body ’s microbiology, biochemistry, or chemistry e. g Candida albicans a normal inhabitant of the epithelia such as the vaginal lining can grow too rapidly like a newly pregnant woman and become pathogenic leading to yeast infections. Due to the spread of AIDS, in recent times many other opportunistic mycosis have become common due to reduced (compromised) immune systems. 1. Structure, Reproduction and classification of some Pathogenic fungi Piedra (Beigels ’ disease) White piedra also called Beigel ’s disease or Chignon disease is a fungal of the scalp, beard, pubis, moustache. It is characterized by a soft, grayish, noodle-shaped structures of variable consistency arranged in rows of the hair shaft to which they adhere. It is caused by a filamentous yeast Trichosporum beigelli that forms blastospores and arthrospores, hyphae and pseudo-hyphae. It is mostly found in young adults of both sexes. A predisposing factor is the development of pubic features. It is readily curable. Diagnosis : It is made by observing the presence of irregular white soft noodles along the hair. Treatment: The simplest method of treatment is by shaving. The application of various topical agents especially 5% salicyclic acid or 1% iodine. White piedra Description: White piedra is a superficial cosmetic fungal infection of the hair shaft caused by Trichosporon beigelii . Infected hairs develop soft greyish-white nodules along the shaft. Essentially no pathological changes are elicited. White piedra is found worldwide, but is most common in tropical or subtropical regions. Clinical manifestations : Infections are usually localised to the axilla or scalp but may also be seen on facial hairs and sometimes pubic hair. White piedra is common in young adults. The presence of irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs is characteristic of white piedra. Laboratory diagnosis : 1. Clinical Material: Epilated hairs with white soft nodules present on the shaft. 2. Direct Microscopy: Hairs should be examined using 10% KOH and Parker ink or calcofluor white mounts. Look for irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs . 3. Culture: Hair fragments should be implanted onto primary isolation media, like Sabouraud's dextrose agar. Colonies of Trichosporon beigelii are white or yellowish to deep cream colored, smooth, wrinkled, velvety, dull colonies with a mycelial fringe. 4. Serology: Not required for diagnosis. 5. Identification: Characteristic clinical, microscopic and culture features. Causative agents: Trichosporon beigelii Management: Shaving the hairs is the simplest method of treatment. Topical application of an imidazole agent may be used to prevent reinfection. Again, the application of various topical agents especially 5% salicyclic acid or 1% iodine. )Types of ringworm infections named according to site of body •Tinea capitis ……………………… .ringworm infection of the hair, scalp., eyebrows (lashes) •Tinea corporis ……………………… smooth body •Tinea manum ……………………… hand •Tinea pedis …………………… foot •Tinea cruris ……………………… groin •Tinea barbae ……………………… beard •Tinea unguium ……………………… nails •Tinea tavosa ……………………… scalp (mostly hair) Dermatophytes are made up of closely related filamentous fungi that infect superficial keratinized tissues of the skin, hair, and nails. The clinical feature they produce is collectively called dermatophytosis or ring worm or tinea . Classification of dermatophytes based on habitat •Anthropophilic •Microsporum audouinii ii) Epidermophyton floccosum iii) Trichophyton rubrum iv) T. violaceum v) T. tonsurans •Zoophilic •Microsporum canis ii) M. nanum iii) Trichophyton mentagrophyte iv) T. verrucosum •Geophilic •Microsporum gypseum ii) Trichophyton ajelloi Sources of ringworm infection •Schools ii) prisons iii) Military camps iv) Warm damp areas like the tropics, moisture accumulation on the clothes and shoes v)Animals such as cats, dogs, cattle, poultry etc. The Main genera of dermatophytes i) Epidermophyton ii) Trichophyton iii) Microsporum Superficial mycosis refers to infections of the skin and appendages Deep mycosis includes the subcutaneous and systemic mycosis which constitutes the infection of deeper tissues and visceral organs. The Cutaneous and Superficial Mycoses CONDITION COMMON NAME LOCATION ON BODY MAJOR SYMPTOM Tinea corporis ringworm any skin surface except scalp, flaky sores with wellfeet, and male facial areas defined ring shapes Tinea capitis cradle cap scalp scaly, swollen blisters or rash of “black dots” Tinea cruris jock itch genitals, buttocks, and inner raised red sores with thighs well-defined edges Tinea unguium nail fungus nail bed of toes and rarely thickened, discolored fingers nail Tinea pedis athlete’s foot toes and soles of feet red flaky rash Piedraia hortai Black piedra scalp hair hair loss from broken hair shafts Trichosporon White piedra pubic, beard, eyebrow, and hair loss from broken beigelii eyelash hair hair shafts Tinea nigra ——— any skin surface red flaky patches Tinea versicolor ——— any skin surface red flaky patches Tinea pedis (ATHLETE ’S FOOT INFECTION) The infection occurs between the toes or toe which produces a clear fluid most of the time. The 4th and 5th toes are always infected. It brings soreness and itching Mode of transmission They are probably transmitted from host to host through infected materials. There are three causal agents •T. rubrum - the source of the inoculums crosses from people with chronic infections because the fungus is not long lived. •T. mentagrophyte and Epidermophyton floccosum - This source of inoculum comes from long lived arthospores that resides in rugs and carpets. There are three grades of infection Grade 1: subclinical and itching between the toe, skin may be soft and macerated, blisters may occur Treatment: keeping feet dry and clean, drying between the toes lightly each time you bath, application of fungicides or ointment. Grade 2: the host at this level is conscious of burning sensation while walking or standing . Treatment: Use of topical fungicides, dusting powder to keep the feet dry, by the removal of clear liquid from the blisters. Grade 3: Here the problem is compounded by a secondary bacterial infection; Treatment: i) Go to bed ii) The use of systemic antibiotics to fight the bacterial infections iii) use of chemicals as soak iv) the persistent cases normally those by T. rubrum , the use of systemic griseofulvin therapy or other antifungal systematic drugs. Athletes feet showing blisters in between the toes Onychomycosis Treatment & Management Onychomycosis, also known as tinea unguium , is a fungal infection of the nail. This condition may affect toenails or fingernails, but toenail infections are particularly common. Treatment may be based on the signs. Treatment may be with the medication terbinafine. Treatment of onychomycosis depends on the clinical type of the onychomycosis, the number of affected nails, and the severity of nail involvement.. Topical antifungals The use of topical agents should be limited to cases involving less than half of the distal nail plate or for patients unable to tolerate systemic treatment. Agents available in the United States include ciclopirox olamine 8% and efinaconazole 10% nail solutions. Amorolfine and bifonazole/urea are