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Introduction Medical Mycology


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Title: Introduction Medical Mycology

Introduction Medical Mycology
(No Transcript)
General Fungi-1
  • Fungi
  • eukaryotic microorganisms
  • Larger than bacteria.
  • Theyre Essentially Aerobic.
  • Mostly found in Nature living in association with
  • Many of them act as harmful organisms.
  • Others free saprophytes types of fungi utilize
    organic matter as an energy source like soil and
    rotten vegetables-on dead organic substances.
  • More than 100000 types.
  • Few associated with human diseases.

Fungi cell Structures
  • About 100 Fungi types are opportunistic
  • Yeasts are part of normal flora in Oral
    cavity-intestine-Vagina and theyre Opportunistic
  • Few types like Cryptococcus neoformans
    capsulated fungi and its antiphagocytotic- are
    true pathogens.
  • All are not susceptible to antibacterial drugs or
  • Fungi Cell wall composed Mostly of complex
    polysaccharides (chitin) with less amount of
    glucan and mannan (polysaccharides).
  • Cell membrane lipid bilayer and its the
    innermost layer arround the fungal cytoplasm
    consists of phospholipids, protein and
    Ergosterol. ergosterol is te target of all
    antifungal agents, which work by disupting
    ergosterols either by binding to it and producing
    holes in the membrane or by interfering
    ergosterols synthesis./ resistance can be
    developed but much slower and its been
    recognized in candida-
  • Cytoplasm contains true nucleus eukaryotic-,
    microtubules composed of tubulin/Specific
    Protein, Mitochondria, Lipids phosphate

Hypha Cell-Yeast Cell
Fungi consist two major groups
  • Yeasts
  • (unicellular cells 0.5-4 um).
  • develop large colonies on culture agar media.
  • Mostly reproduce asexually by budding one or more
  • A few reproduce by binary fission.
  • When buds dont separate they from long chains of
    yeast cells called Pseudohyphae. And this happens
    when its attached to our mucosa causing
    infections, so its pathogenic.
  • Baker's yeast Saccharomyces cerevisiae. it
    ferments glucose producing Co2 alcohol which
    are very helpful in Production of Bread
    (baking), Vitamins, Biogenetic and in Medical
    drugs synthesis like Insulin. (Non-pathogenic)

Growth of Yeast Cell
  • 2. Molds (filamentous Fungi)
  • composed of various cellular structures
    (Multicellular colonies)
  • Have different morphological types of Hyphae
    (filaments). Composed of clumps of interwind
    banching hyphae.
  • Extension of single spore (hypha cell) into
    branching nest of filamental cells. grow by
    longitudinal extension.
  • (((Explanation of all above it reproudce by
    spores which are hypha cells, these spores start
    to extend in longitudinal directions to form
    filaments hyphae- and they got different
    morphological types because of interwinding of
    these hyphae in different shapes. And then the
    top of these hyphae produce sores once again upon
    exposure to oxygen)))
  • Watch the first minute in this video and youll
    get the idea http//
  • reproduction by spores - the reproductive bodies
    of molds-, hyphae.
  • Single cells are up to 20um.
  • Growth in vitro gives you Aerial Vegetative
  • Vegatative are the horizontal filaments which
    absorbs nutrients
  • And support growth but Ariel is the portion of
    mycelium that grows
  • upward or outward from the surface of the
    substrate, and from which propagative spores

Filaments Fungi/ Molds
  • Molds form multicellular filaments (hyphae)
    and could be non-septat or septat hyphae.((A
    hypha consists of one or more cells surrounded by
    a tubular cell wall. In most fungi, hyphae are
    divided into cells by internal cross-walls called
    "septa" (singular septum). Septa are usually
    perforated by pores large enough for ribosomes,
    mitochondri and sometimes nuclei to flow between
    cells. Some fungi have aseptate hyphae, meaning
    their hyphae are not partitioned by septa.))
  • It produce spores of different sizes
    structures, arrangement and color.
  • A mass of hyphae and spores is represented by
    Aerial Vegetative Mycelium (as calrified in the
    previous slide)
  • Dimorphic Pathogenic fungi grow as Yeasts or
    Yeast-like structure in vivo at 37C, but as in
    vitro as Molds 20 -40C.
  • Lab Identification Direct smear , Culture on
    Sabourauds dextrose agar or blood agar.
  • Slow rate varies from Slow to rapid growth (2-30
  • Can be identified DEPENDING ON Morphology,
    reproduction of ((spores/yeast cells/ Filments
    (Hyphae)), Colors of Micro/Macro Conidia
    (SPORES), Arrangement of spores on vertical
    hyphae /aerial mycelium , Hyphae with or without
    septa / single septum AND type and color of
  • No specific antibodies/ serological tests

Filmental Fungi(MOLDS) are like Pencilliun
Growth of Fungi
  • Fungi have chemoheterotrophic metabolisms which
    means obtaining nutrients and energy through
    decomposing complex organic materials and Plants
    biomass -The mass of organic material produced by
    living organisms.- into small molecules basic
  • Require water/ moist, carbon source various
    minerals for growth
  • Certain type of fungi called mushrooms can be
    used as food and have high nutritional value
    (Minerals) and Some of mushrooms produce
  • Fungi contaminate most types of food and may
    cause fatal disease.
  • Few Fungi produce mycotoxins, which is the fungal
    toxin. One type of molds can produce many types
    of mycotoxin and one type of mycotoxin can be
    produced by many types.

1-Aminata Toxic Mushroom 2-Non-Toxic Mushroom in
Growth in Human tissues
  • Pathogenic Yeasts produce often elongated oval
    cells Pseudohyphe on body mucosal cells when
    attached to it, causing Mild inflammation and
    cause erythematic lesions - Redness of the skin
    caused by dilatation and congestion of the
  • Pathogenic Molds single and multiply filaments.
    cell fragments in infected tissue and Rarely form
    spores. Causes Superficial lesions without
  • They multiply filaments not spores because spores
    need high amount of oxygen which is not found
    inside the body
  • Antifungal drugs Nystatin, Fluconazol,
    Amphotericin B, Casbofungin . All react with
    ergosterol forming compmex molecules and damage
    cell membrane.

Budding Yeast Germ Tubes demonstrated in
Serum test
Capsulated Yeast / Cryptococcus neoformans
(India ink test) this test can make the capsule
Human Mycosis-1
  • Dermatophytosis (Superficial Mycoses/ Cutaneous
  • Dermatophytes category of cutaneous fungal
    infections and the most common dermatophytes
    include Trichophyton, Microsporium and
    Epidermophyton .
  • Include many species distributed Worldwide.
  • Grow by Spores, Hyphae fragments.
  • Transmitted to human, animals environment.
  • Ringworm / Tinea corporis A superficial
    dermatophyte infection characterized by
    either inflammatory or non-inflammatory lesions
    on skin , Erythematic lesion cause Allergic
    reaction. Involve superficial keratinize/Dead
    tissue like skin, hair, Nails. the fungi spread
    frorming a ring shaped with a red raised border,
    the border is the inflamation and the center is
  • All dermatophytes can cause similar skin lesions

Human Mycosis-3
  • 2. Tinea capitis in Hair infected Hairshaft
    /hair follicles and Scalp???? ????? either
    Endothrix (invades hair shaft) or Exothrix
    (infects hair surface).
  • Composed of large number of spores and sticky
  • Common in Children and Rare in Adults.
  • Infection spread rapidly by contact with infected
    hair (Outbreaks in schools.)
  • 3. Tinea unguium In Nails
  • 4. Tinea pedis ??? ??????? in Feet fingers
    interspaces between fingers. Theyre moist skin
    lesions. Common in Adults, and can develop to
    chronic lesion and its difficult to cure. It
    requires moist and warmth, so happens mostly with
    those wearing shoes.
  • Causative agents Mostly Epidermophyton species.
    Less Trichophyton Microsporium species

  • Tinea versicolor (Pityriasis versicolor)caused by
    Malassezia furfur is a common lipophilic yeast,
    part of normal skin flora and Lives on oils and
    fats. Mostly causes endogenous infection.very
    common among young adults.
  • Clinical Features Discoloration (hyper/ hypo
    pigmentation skin spots on face, arms or any body
    site) Rarely erythematic skin lesions, causes
    Allergic reaction and Skin scaling. Activated by
    various factors like stress conditions, fever,
    warm humid environment.
  • Diagnosis Clinical picture, Direct smear
    spherical thin filaments yeast (its only
    diagnosed by filaments). Theres Difficulty in
    isolation, cultivation identification. Mostly
    Self-limited 1-3 weeks

Tinea corporis Pityriasis versicolor
Tinea unguium Tinea
Penicillinums Trichophyton
Yeast /Candida species
  • Candidiasis/ Candidiosis mostly C. albicans
    (50-70) and Less C. glabrata, C. tropicalis., C.
    Krusei Others spp.
  • Part normal body Flora in Mouth(oral cavity),
    Vagina, Skin, Intestine, Urinary tract.
  • Opportunistic Pathogens mostly endogenous
    infection, arising from 1) overgrowth of the
    fungus 2)Radiation 3) Toxic drugs 4) intensive
    use of antimicrobial drugs so we Inhibiting
    normal flora and Candida activated (Underlining
    diseases), it causes different or more severe
    infections in immunocompromised host.(like
    systemic infections)
  • Exogenous infection transmitted from catheters
    or prosthetic devices or Respiratory tubes or
    person-to-person transmission, causes Common
    Nosocomial Infection.
  • Clinical Features
  • oral thrush mucosa (patches of creamy white
    exudates with reddish base over the mucose),
    Throat- Pharynx, can transmitted to Lung.
  • vaginal Candidiasis discharge Irritation.
  • Candidemia, meningitis. (in immunocompromised

Candida Pseudohyphae ( Chlamydo-Blastospores)-B
lastospores is dimorphic-
Candida Thrush
Other Yeast Infection
  • Encapsulated C. neoformans Large Capsule, causes
    a chronic- subacute- acute pulmonary infection,
    May spread to blood, CNS and causes systemic
    disease or meningitic disease. Often isolated
    from pigeon, Birds excreta.
  • C. neoformans has a world-wide distribution. Now
    its one of the most significant opportunistic
    pathogens in humans. Most cases are identified in
    immunodifficient and AIDS patients. Like ¾ of the

Mold infection Aspergillosis-1
  • Aspergillus species are common in nature, Spores
    spread with dust particles anf we uptake it by
  • Few develop Allergy or clinical disease
  • A. fumigatus, A. flavus, A. niger.
  • Causes Common Human Aspergillosis
  • 1- Allergic Bronchopulmonary Aspergillosis
    caused by the Presence of conidia(spores) or
    transient growth of the organism in body, causing
    Respiratory tract infection associated with
    Granuloma ,allergic reaction, eosinophilia,Lung
    Asthma, Nose/Sinusitis and Ear/Otitis externa
    (Otomycosis) which is often associated with
    swelling, pain black discharge.

  • 2- Pulmonary lesions in preformed cavities
    (Aspergilloma) and debilitated tissues. people
    with lung cavitations like in TB develop this
  • Common in Tuberculosis Lung carcinoma
  • Can grow aspergillus fungal ball in the cavity
    and requires a surgical removal
  • fatal.
  • And causes Localized Lesions in Eyes, Sinuses,
    External Otitis infection treated by Surgery
    Antifungal Treatment.
  • --------------------------------------------------
  • Fungi produce toxins called Mycotoxicosis
    Worldwide million cases due to ingesting
    contaminated foods with mycotoxin-talked about it
    previously-. Mostly mild gastrointestinal
    symptoms and caused by various fungi.
  • The toxin that is produced by Aspergillosis (A.
    flavus) is called Aflatoxins. And its fatal.
  • Few micrograms of aflatoxin cause acute Liver
    cirrhosis, Edema hemorrhage in lung kidneys,
    coma Death.
  • Found common in Grains, Peanuts, Ground nuts,
    Rice, Milk Powder, Due to storage food under bad
    not dry condition.

1-Aspergillus niger growth2- Wet preparation,