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Diagnosis of superfacial and cutaneous mycoses

Presented : by Dr. nouripour-sisakht

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Medical mycology

Reference1. www.mycology.adelaide.edu mycology online

2. Medical mycology: Dr. Zainii

3. Medical mycology: Dr. Shadzie

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INTRODUCTION TO MEDICAL MYCOLOGY

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001

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Introduction• Fungus( Myco )………… Fungi

• Mycology: genetic and biochemical properties, their taxonomy, and their use to humans as source for medicinals (e.g., penicillin), food (e.g., beer, wine, cheese, edible mushrooms), as well as their dangers, such as poisoning or infection

• Medical mycology: study of mycoses of man and their etiologic agents.

• 400000 ( soil, Air, Water )— Human

• Pathogen ( 100 up to 200 )

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General characterization Fungi ( yeast and molds) Eukaryote( true

nucleus) - Size: 2 -10 µ - PH : 2-9 (6.8) -Temperature : 25-30 ( A. fumigatus ) - Humidity : 80-95 % -Devoid of chlorophyll - Heterotrophic C.N - mineral( Fe, Mn , Zn , p … - Vitamin(B group and biotin)

- aerobic11

Fungal structure

o Cell wall : polymers of polysaccharide

chitin (70%) – Glucan – Mannan- cellulose

rigid cell wall non-motile Capsule ( evade phagocytosis) cryptococcuso Plasma membrane………….. Ergostrol

o cytoplasm consist of various organell:o Ribosome 80S , Mitochondria , Endoplasmic

reticulum , lysosom, microtubules and a membrane enclosed nucleus.

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• Chitin is a polysaccharide composed of long chain of n-acetyleglucasamine.

• the fungal cell wall contain other polysaccharide, B-glucan, which is the site of action of some antifungal drugs.

• Ergosterol is the site of action of antifungal drugs, amphtericin B & azole group

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Life styleSaprophyte• Feed on dead tissues or organic waste

(decomposers) ( Saprophyte…….,,,,,……Opportunist)

Pathogen• Feeding on living tissue of a host.( pathogen)

-Animal - Human- Plant

- systemic mycoses and dermatophytes

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Study of fungi

Kind of fungi: Mushroom

• Amanita amanitin mycetismus

• Microscopic: Yeast Mould Dimorphic

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Hyphal growth from conidia

myceliumgerminatingspore

• Conidia Hyphae Mycelium Colony17

• Hypha (hyphae plural) - fundamental tube-like structural units of fungi.– Septate - divided by cross walls.– Aseptate (coenocytic) - lacking cross walls.

• Mycelium - a mass (mat) of hyphae forming the vegetative portion of the fungus.– Aerial - growing or existing in the air.– Vegetative - absorbs nutrients.– Fertile - bears conidia (spores) for reproduction.

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mycelium: septate mycelium: non septate 19

Hyphae may have some specialised structure or appearance that aid in identification Some of these are:

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(Mold)Mould colony• Surface: velvety,

powdery Cottony

• Pigmentation

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Yeast• Unicellular (round-oval) Bud ( budding)

• Pseudohypha

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Dimorphism

• Thermal dimorphism Sporothrix

• Non thermal dimorphism Candida, Malassezia

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Habitat

• Exogenous : soil, plants, water, air

• Endogenous: Candida albicans Malassezia

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Beneficial Effects of Fungi:

• 1. Decomposition - nutrient and carbon recycling.• 2. Biosynthetic factories. The fermentation

property is used for the industrial production of alcohols, fats, citric, oxalic and gluconic acids.

• 3. Important sources of antibiotics, such as Penicillin.

• 4. Model organisms for biochemical and genetic studies. Eg: Neurospora crassa

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Beneficial Effects of Fungi:• 5. Some fungi are edible (mushrooms).• 6. Yeasts provide nutritional supplements such as vitamins and

cofactors.• 7. Penicillium is used to flavour Roquefort and Camembert cheeses.• 8. Ergot produced by Claviceps purpurea contains medically

important alkaloids that help in inducing uterine contractions, controlling bleeding and treating migraine.

• 9. Fungi (Leptolegnia caudate and Aphanomyces laevis) are used to trap mosquito larvae in paddy fields and thus help in malaria control

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Harmful Effects of Fungi:

• 1. Destruction of food, lumber, paper, and cloth.• 2. Animal and human diseases, including allergies.• 3. Toxins produced by poisonous mushrooms and within food

(Mycetism and Mycotoxicosis).• 4. Plant diseases.• 5. Spoilage of agriculture produce such as vegetables and cereals

in the godown.• 6. Damage the products such as magnetic tapes and disks, glass

lenses, marble statues, bones and wax.

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Fungal Pathogenicity (virulence factors):

• Ability to adhere to host cells by way of cell wall glycoproteins

• Production capsules allowing them to resist phagocytosis

• Ability to acquire iron from red blood cells as in Candida albicans

• Ability to damage host by secreting enzymes such as keratinase, elastase, collagenase

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Continue• Ability to resist killing by phagocytes as in

dimorphic fungi• Ability to secrete mycotoxins• Exhibiting thermal dimorphism• Ability to block the cell-mediated immune

defences of the host.

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Host defence factors• Physical barriers, such as skin and mucus membranes• The fatty acid content of the skin• The pH of the skin, mucosal surfaces and body fluids• Epithelial cell turnover• Normal flora• Most fungi are mesophilic and cannot grow at 37oC.• Natural Effector Cells (polymorphonuclear leucocytes) and the

Professional Phagocytes (monocytes and macrophages)

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Factors predisposing to fungal infections:

1. Prolonged antibiotic therapy2. Underlying disease (HIV infection, cancer,

diabetes, etc.)3. Age 4. Surgical procedures5. Immunosuppressive drugs6. Irradiation therapy7. Indwelling catheters8. Obesity9. Drug addiction10.Transplants11.Occupation

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Reproduction

• A sexual the major method for the maintenance and

dissemination of many fungi.• Sexual

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Asexual reproduction anamorph state (mitosis)

1. Budding (fission)2. Conidia (Microconidia and

Macroconidia)3. Artroconidia (holoartric, entroartric)4. Chlamydoconidia5. sporogenesis Sporagiospor…

sporang

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Sexual teleomorph (meiosis)• Sexual

teleomorph (meiosis)AscosporZygosporBasidiospor

Oospor

Plasmogamy karyogamy meiosis

Homothalic Heterothalic

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Ascospore - spore formed in a sac-like cell known as an ascus. Often eight (8) spores formed. (Ascomycetes)

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Zygospore - a thick-walled spore formed during sexual reproduction (zygomycetes)

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Classification of fungi• Zygomycotina hyphea

mostly aseptate - Rhizopus, Mucor

• Ascomycotina Arthroderma,

Pseudallescheria, Piedraia hortae

• BasidiomycotinaCryptococcous neoformanceMushroom poisining• Deutromycotina

• }Perfect fungi

• }Imperfect fungi 39

Mycoses

• Superficial - Confined to the outermost layers of the skin and hair. No host cellular or inflammatory response due to organisms being remote from living tissue. Essentially no pathology; the disease is recognized purely on cosmetic basis.

• Cutaneous - in the keratin of the skin, nails, and hair. These organisms prefer non-living cornified layers. The disease is called a dermatophytosis or dermatomycosis. Host response is patchy scaling or eczema eruptions. They are classified according to the area of the body that is involved. 40

Mycoses

• Subcutaneous : Involve the deeper layers of skin and often muscle tissue. Man is an accidental host following inoculation of fungal spores via some form of trauma. This type of infection is often identified by the presence of a characteristic tissue reaction or granule.

• Systemic : Attack the deep tissues and organ systems; often creating symptoms that resemble other diseases.

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Mycoses

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1. Aspergillus + osis = aspergillosis2. Mucor + mycosis = mucormycosis3. Trush4. Tinea versicolor

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Fungal specimen

Skin( scale)-Hair-Nail clippingsPus- Exudates- Sputum- serumenUrine-Blood- CSF- Bone marrow corneal scraping, discharge or pus from lesions and biopsy

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Transported to the laboratory without any delay

Biopsy specimens must be transported in saline

Diagnosis of fungal infection

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Chemical classes Drugs targets

Allylamines andthiocarbamates

Terbinafine , NaftifineTolnaftate,Liranaftate

Ergosterol synthesis

Azoles Tioconazole, ClotrimazoleEconazole, MiconazoleKetoconazole, FluconazoleItraconazole , TerconazoleVoriconazole, Posaconazole

Ergosterol synthesis

Polyenes Amphotericin B , Nystatin

Ergosterol(membrane function)

Pyrimidine Flucytosine DNA and RNASynthesis

Echinocandins Caspofungin, MicafunginAnidulafungin

Glucan synthesis

Antifungal drugs- by structure and mode of action

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Thank You

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mycosesSuperficialcutaneoussub cutaneous Systemic

Malassezia infections

• Pityriasis versicolor• Pityriasis folliculitis• Seborrhoeic dermatitis and dandruff: • Fungaemia:

Pityriasis versicolor (tinea versicolor)

• Definition• is a common, mild, but often recurrent infection of the stratum corneum

due to lipophilic yeasts of the genus Malassezia.

Geographical distribution• The disease is worldwide in distribution, but is

much more prevalent in tropical and subtropical regions.

Causal organisms (Malassezia species)• M. furfur, • M. pachydermatis (non obligate lypophile)• M. sympodialis, • M. globosa• M. obtusa, M. restricta and M. slooffae

• Normal flora……… endogenous in origion• prevalent in hot, humid tropical and subtropical climates,

where 30-40% of the adult population may be affected.

• Human-to-human transmission of Malassezia species is possible, either through direct contact or via contaminated clothing or bedding. In practice, however, infection is endogenous in most cases and spread between persons is uncommon.

• The characteristic lesions consist of patches of fine brown scaling, particularly on the trunk, neck and upper portions of the arms.

• In light-skinned: may appear darker than normal• In dark-skinned or tanned individuals: affected

skin loses colour and becomes depigmented.• The disease is exacerbated by sunlight and

sweating.

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The lesions of pityriasis versicolor and seborrhoeic dermatitis have a predilection for sites wellsupplied with sebaceous glands, such as the chest, Back and upper arms

Risk factor

• Stress• Chronic infection• Hyperhydrosis• Malnutrition• Broad spectrum antibiotics• Overweight• Steroid therapy • …………………………

Differential diagnosis

• Erythrasma• Seborrhoic dermatitis• Tinea corporis• Naevi• Vitiligo• chloasma

Pityriasis Versicolor

DiagnosisMic: short hyphae, Yeast cells (spaghetti)Wood light …..Golden yellowCulture

Therapy: topical selenium Sulfide 2% shampoo

Wood's ultra-violet light

Malassezia ovalis????Malassezia Species.

• Less frequently,these organisms cause serious systemic infection in low-birth-weight infants and other mmunocompromised and debilitated individuals

Erythrasma

• Chronic Bacterial infection (folds)• axillae, interspaces of the toes, • ETIO: Corynebacterium minutisimum

• Wood light……..Coral red

• Therapy - Erythromycin

Wood light……..Coral red