Fungal Infections: Types, Causes, & Treatment - PDF

Fungal infections Superficial infections Superficial/cutaneous Cutaneous infections infections Subcutaneous infections Systemic infections Opportunistic infections Questions 1. How would you know that you might have a fungal skin infection ?...

Fungal infections Superficial infections Superficial/cutaneous Cutaneous infections infections Subcutaneous infections Systemic infections Opportunistic infections Questions 1. How would you know that you might have a fungal skin infection ? skin scraping culture - observe - 2. How can you confirm that you have a fungal skin infection ? under 3. How might the fungus be transmitted to your skin ? microscope Learning outcomes To be able to define the different types of fungal infections. To be able to describe the disease pathogenesis, characteristics of the etiological agent and source of infection (transmission route) for commonly occurring fungal infections.  less invasion - not deep Superficial infections - X involve hair root does not involve living tissue skin & hair shaft infections no inflammatory reaction immune response not elicited – non-living tissue colonized (dead layers of the stratum corneum) Predisposing factors – hot, humid conditions - various immunosuppression, malnourished Deeper infections – abnormality in local, systemic immunity 1. Pityriasis versicolor (panau) likes Lipid(sebum) Lipophilic yeast Malassezia furfur (M.globosa, M.pachydermatis) M.furfur - commensal on skin (frequently colonizes skin, esp. adolescence) ~ -X use body as host harmful Infection : transition from yeast to mycelial form (short hyphae) – oily skin, genetic factors etc. Chronic lesions on trunk, arms, shoulder, back Hyper/hypopigmented areas (depigmentation) Lesions join, become larger, fine scales Asymptomatic apart from skin discoloration Rarely deeper skin invasion – erythema, pruritis  Pityriasis versicolor showing hyperpigmented lesions in a Caucasian and hypopigmented lesions in an Australian Aborigine. The colour varies according to the normal pigmentation of the patient, exposure of the area to sunlight, and the severity of the disease. Fungal metabolite (azelaic acid) may affect pigment formation in the skin. Skin scrapings taken from patients with Pityriasis versicolor stain rapidly when mounted in 10% KOH, glycerol and Parker ink solution and show characteristic clusters of thick-walled round, budding yeast-like cells and short angular hyphal forms up to 8 um in diameter (ave. 5 um diam.). These microscopic features are diagnostic for the causative agent Malassezia furfur and culture preparations are usually not necessary. - lab test not necessary, shin can observe directly. Other superficial infections caused by Malassezia spp. Seborrhoeic dermatitis – (inflammation of areas rich in sebaceous glands), dandruff, folliculitis. Relevance of yeast in these cases not proven, (other immunological factors may be involved) but antifungal treatment (removal of yeast) can improve/cure condition.  not common ~ 2. Tinea nigra ~ rure infection darkly pigmented Halophilic fungus Hortae↑ werneckii (Exophiala werneckii) (dematiaceous fungi) Brown/black lesions on palms, feet. Fungus present as melanized cells on dead skin layer. Coastal areas (endemic in Carribbean, Central & South America, Asia, Africa) Not common infection (‘Tinea’ infection – in the strictest sense should refer to infections caused by dermatophytes) Tinea nigra : typical brown to black, non-scaling macules on the palmar aspect of the hands. Note there is no inflammatory reaction.  Genus:Hortae(Exophiala) Species: werneckii Disease(s):Tinea nigra Image Type:Macroscopic Morphology Image Legend: Hortae werneckii on Sabouraud's dextrose agar. Initially colonies are mucoid, yeast-like and shiny black. However with age they develop abundant aerial mycelia and become dark olivaceous in colour. 3. Black piedra Piedraia hortae (dematiaceous fungi) Soilfungi Humid, tropical areas (Central & S. America, SE Asia, S.Pacific islands) Hair infection Hard, black nodules on hair shaft (on scalp) Nodules : dense fungal cells - microscopic to large in size Hair may break after prolonged fungal growth to rid of it -cut hair get Genus:Piedraia Species: hortae Disease(s):Piedra, black Image Type:Macroscopic Morphology Title:Black piedra 4. White piedra Trichosporon spp. Fungal growth outside of hair shaft Hair on scalp, axilla, crural area, (rarely beard, eyebrow) Soft nodules : white, pale green, or yellow, easily pulled off hair Hair not invaded, but may break off after prolonged infection Genus : Trichosporon Species: beigelii Disease(s):Piedra, white Image Type:Microscopic Morphology Title:White piedra Image Legend:Mass of hyphae and arthroconidia surrounding a hair. Superficial infections - summary Skin & hair shaft infections 4 infections : 1. Pityriasis versicolor & Malassee in Furtur) 2. Tinea nigra Italophilic fungi 3. Black piedra Piedraiai hortae 4. White piedra Trichosporin app- Cutaneous infections skir Plant (fungi) Dermatophyte - 3 genera : Microsporum, Trichophyton, Epidermophyton Skin, nail & hair infection (incl. hair root) ‘tinea’ infection (ringworm) Keratinized tissue of stratum corneum colonized, fungus invades skin and appendages. Most common fungal infection Dermatophyte infections Dermatophytosis enlyme aeratin o Virulence factor for dermatophyte – keratinase enzyme – digests keratin of stratum corneum, hair, nails Dermatophyte – balance between host & fungi : some coexist with humans, others are parasitic Infection – heals spontaneously or persists for years Lesion – due to host’s immune response to fungal enzymes (inflammation depends on fungal species & host).  inside body Infective material – conidia produced in vivo Infection – through direct contact (skin scales, air, animals, clothing) Infective material remains infectious for a long time in environment Dermatophytes produce 2 types of conidia : macroconidia (large, multicell) & microconidia (small, unicell) Skin infection - kurap  Microsporum – macro & microconidia, skin & hair infections (rarely nails) Trichophyton – macro & microconidia, infects skin, hair & nails Epidermophyton – macroconidia, skin & nail infection Dermatophytes grouped according to natural habitat : geophilic - soil anthropophilic - humans zoophilic - animals  KOH mount of infected skin scales (left) and nail material (right) showing typical dermatophyte hyphae breaking up into arthroconidia Microsporum Tricophyton Epidermophyton Species Incidence Anthropophilic spesies T. rubrum +++ T. tonsurans + T. mentagrophytes v. interdigitale E. floccosum ++ M. audouinii ++ Zoophilic spesies M.canis ++ T.mentagrophytes v. mentagrophytes ++ Geophilic species M.gypseum Tinea pedis (athlete’s foot) between toes, foot soles - scaling, erythema, itching, burning E.floccosum, T.ment v. ment, T.ment v. interdigitale, T.rubrum Tinea cruris groin, perianal, upper thigh scaly lesions, erythema, itching, burning - T.rubrum, E.floccosum Tinea corporis trunk, shoulder, back, axilla well marginated lesions with vesicular borders - T.rubrum, T.tonsurans  Tinea pedis caused by T. rubrum. Sub-clinical infection (left) showing mild maceration under the little toe and more severe infection showing extensive maceration of all toe web spaces "Moccasin-type" tinea pedis caused by E. floccosum Tinea capitis and corporis caused by M. canis following contact with infectious kittens Tinea capitis - scalp, hair - erythema, scaling, partial alopecia - M.canis, M. adouinii, M. gypseum Tinea manuum - hands - T.rubrum Tinea unguium - nails - T.rubrum, T. ment., E. floccosum - nail infections can also be caused by other fungi Tinea capitis showing extensive hair loss caused by M. canis. KOH mount of infected hairs showing "small spored" ectothrix invasion by M. canis and "large spored" ectothrix invasion by M. gypseum KOH mount of an infected hair showing an endothrix invasion caused by T. tonsurans  Tinea of the toe nails caused by T. rubrum Tinea of the finger nails caused by T. rubrum (top) and T. tonsurans (bottom) Cutaneous infections Other fungi also cause cutaneous infections Candida spp - skin & mucus membranes Scytalidium spp., Fusarium spp., Candida spp., Aspergillus spp., etc. – nail (onychomycosis) Disseminated infection from subcutaneous or systemic infection Mostly opportunistic infections Summary Pityriasisversicolor – most common superficial fungal infection Tinea – most common fungal infection, caused by dermatophyte fungi Both infections occur in healthy individuals SUBCUTANEOUS INFECTIONS Case study – subcutaneous fungal infection A 51-year-old housewife came to the dermatology outpatient department on 9 February 2010, with multiple nodules on her left forearm. She gave a history of injury to her left little finger while cutting grass in her garden ten months ago. A nodule developed within days which ulcerated forming scaly ulcers with itching and it gradually spread. Subcutaneous infections Traumatic implantation of fungi (via wound) Involves deeper layer of dermis, subcutaneous tissue or bone Chronic infection, not lethal Lesions on skin surface Caused by soil saprophytes Worldwide distribution (farm workers)  1. Mycetoma Eumycotic mycetoma - infection caused by fungus - Madurella sp., Exophiala sp., (dematiaceous) Pseudoallescheria (Scedosporium) sp., etc. Actinomycotic mycetoma - bacterial infections : Nocardia sp., Actinomyces sp. Fungal infection : fungus aggregates to form granules, tumor-like abscesses form (immune reaction), swelling, granular discharge, localized. Bone invasion may occur. In tropical, subtropical areas : India, Pakistan, Somalia, S.America Figure 1: Eumycotic mycetoma (a and b). A female patient with gross swelling of the left foot and ulcers in various stages of healing, with serosanguinous discharge from the active ulcer. Furthermore, evident is the pigmentary changes on the overlying skin Genus:Madurella Species: mycetomatis Disease(s):Mycetoma Image Type:Macroscopic Morphology Islack a Image Legend:Many sclerotia (syn. grains, granules) in tissue from mycetoma. Direct microscopy. Difference between mycetoma causing organisms on basis of Gram stain Mycetoma causing organisms and the colour of grains they produce 2. Chromoblastomycosis Localised infection, cutaneous & subcutaneous infection -Fonsecaea sp., Phialophora sp., Cladosporium sp., etc. (dematiaceous fungi) Infection : wound, nodules form, ulcerate, tissue proliferation, lesions enlarge, become verrucose, scaly Lesions – due to innate immune response Worldwide distribution – esp. tropical, subtropical areas – S.America, Africa Genus:Fonsecaea Species: pedrosoi Disease(s):Chromoblastomycosis Image Type:Clinical Presentation Title:Verrucose lesion Image Legend:Verrucose form of chromoblastomycosis. Nail damage is due to lack of blood flow caused by damage to capillary bed. Genus:Fonsecaea Species: pedrosoi Disease(s):Chromoblastomycosis Image Type:MacroInfection Title:Chromoblastomycosis 3. Sporotrichosis Caused by Sporothrix schenkii – dimorphic fungus. Ulcerative infection of cutaneous & subcutaneous tissue. Spread through lymphatic system. Nodules form at site of infection and along lymphatic lines. lymphocutaneous infection Rarely spreads to bone, muscle, organs. Most common subcutaneous infection. In Malaysia – gardeners (rose growers), contact with felines - more susceptible. Pulmonary/disseminated sporotrichosis – in patient with underlying disease, malnourished. Genus:Sporothrix Species: schenckii Disease(s):Sporotrichosis Image Legend:Lymphocutaneous sporotrichosis showing typical elevated subcutaneous nodules developing along the regional lymphatics of the forearm. Genus: Sporothrix Species: schenckii Disease(s): Sporotrichosis Image Type: Macroinfection Title: Lesion Localized lesion. Case study – subcutaneous fungal infection A 51-year-old housewife came to the dermatology outpatient department on 9 February 2010, with multiple nodules on her left forearm. She gave a history of injury to her left little finger while cutting grass in her garden ten months ago. A nodule developed within days which ulcerated forming scaly ulcers with itching and it gradually spread. Subcutaneous infections in Malaysia Sporotrichosis - 19 cases in 6 years (2004-2010) at HKL – cutaneous, lymphocutaneous & disseminated From 2011-2015 – 51 cases at Hospital Ipoh. Due to trauma, especially cat scratch/bites. Large numbers of Sporothrix organisms in the mouth, nasal cavity, nails and faeces of infected cats. Increase in feline & human sporotrichosis. Subcutaneous infections – summary Chronic infections Due to injury Other subcutaneous infections : - uncommon - single, localised lesion at trauma site - caused by dematiaceous fungi