Introduction Medical Mycology

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Introduction Medical Mycology
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(No Transcript)
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General Fungi-1

• Fungi
• eukaryotic microorganisms
• Larger than bacteria.
• Theyre Essentially Aerobic.
• Mostly found in Nature living in association with
  plants.
• 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.

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Fungi cell Structures

• About 100 Fungi types are opportunistic
  pathogens.
• Yeasts are part of normal flora in Oral
  cavity-intestine-Vagina and theyre Opportunistic
  pathogens.
• Few types like Cryptococcus neoformans
  capsulated fungi and its antiphagocytotic- are
  true pathogens.
• All are not susceptible to antibacterial drugs or
  phages.
• STRUCTURE
• 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
  granules.

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Hypha Cell-Yeast Cell
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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
  buds.
• 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)

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Growth of Yeast Cell
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• 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//www.youtube.com/watch?v9kcKF
  8stsIM
• reproduction by spores - the reproductive bodies
  of molds-, hyphae.
• Single cells are up to 20um.
• Growth in vitro gives you Aerial Vegetative
  Mycelium
• 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
  develop.

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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
  days).
• 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
  spores.
• No specific antibodies/ serological tests

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Filmental Fungi(MOLDS) are like Pencilliun
Aspergillus
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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
  elements.
• 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
  Antibiotics.
• 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.

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1-Aminata Toxic Mushroom 2-Non-Toxic Mushroom in
Nature
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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
  capillaries-
• Pathogenic Molds single and multiply filaments.
  cell fragments in infected tissue and Rarely form
  spores. Causes Superficial lesions without
  inflammation.
• 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.

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Budding Yeast Germ Tubes demonstrated in
Serum test
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Capsulated Yeast / Cryptococcus neoformans
(India ink test) this test can make the capsule
visualized
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Human Mycosis-1

• Dermatophytosis (Superficial Mycoses/ Cutaneous
  Mycoses)
• 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.
• CAUSES MANY INFECTIONS LIKE
• 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
  healing.-
• All dermatophytes can cause similar skin lesions
  

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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
  material.
• 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

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• 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

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Tinea corporis Pityriasis versicolor
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Tinea unguium Tinea
Tineacapitis
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Penicillinums Trichophyton
spp.(derma)
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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
  patients)

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Microconidia-Macroconidia
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Candida Pseudohyphae ( Chlamydo-Blastospores)-B
lastospores is dimorphic-
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Candida Thrush
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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
  cases.

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Mold infection Aspergillosis-1

• Aspergillus species are common in nature, Spores
  spread with dust particles anf we uptake it by
  Inhalation.
• 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.

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Aspergillosis-2

• 2- Pulmonary lesions in preformed cavities
  (Aspergilloma) and debilitated tissues. people
  with lung cavitations like in TB develop this
  disease-
• Common in Tuberculosis Lung carcinoma
  patients.
• 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.
• --------------------------------------------------
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• 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.

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1-Aspergillus niger growth2- Wet preparation,
Aspergillus