My Parasitology & Mycology Notes

Parasitology

Short notes P&M can click

Medical parasitology

Parasite: living org acquire some of its basic nutritional requirements through intimate contact with another living org

Eukaryote: well defined chromosome in a membrane-bound nucleus

Protozoa: unicell

Metazoa: multicell

Endoparasite: lives within

Ectoparasite: lives on external surface

Host: org in or on parasite lives and cause harm

DH: org in which adult or sexually mature stage of parasite lives

IH: org in which parasite lives during a period of its development only

Zoonosis

Vector: a living carrier transport pathogenic org from infected to non infected host

Egg

• developing embryo
• fertilized, ready to hatch
• have an operculum except schistosoma

Miracidium

• covered in cilia, slipper shaped
• leaves eggs, swim around looking for first intermediate host, a snail
• burrows into 1st host, loses cilia
• turns into sporocyst or redia

Sporocyst

• miracidium penetrates snail mantle 
• turns into sporocyst
• "sac" of embryos 
• it releases embryos into snail
• embryos can become sporocyst, redia or cercaria

Redia

• has pharynx, small digestive system
• more mobile than sporocyst
• embryos turn into redia or cercaria

Cercaria

• leave snail, find next host
• looks like a miniature adult with a tail
• tail for swimming
• loses tail as penetrate next host
• schistosoma cercaria have forked tails 

Metacercaria

• "resting"
• miniature adult curled up in a tissue cyst (bubble on body wall)
• wait for intermediate host to be eaten by DH

Adult

• flat, leaf shaped
• male and female organs in same individual 
• adult schistosoma are round
• sexes separated
• male larger than female

Taenia saginata

• scolex no hooks
• may have tiny rostellum
• 4 suckers
• 1000~2000 proglottids
• 14~32 uterine branches 
• 2 ovary

Taenia solium

• scolex has 2 rows of hooks on a prominent rostellum
• 4 suckers 
• 7~1000 proglottids
• 7~11 uterine branches
• 3 ovary

Mycology

Mykos; fungus

Mycoses: disease

Mycotoxins: toxin produced

Fungi: eukaryotic, spore-bearing, heterotrophic org that produce extracellular enzymes and absorb their nutrition

Characteristics

• eukaryotic
• facultatively anaerobic, strictly aerobic
• chemotropic
• heterotrophs
• spores
• chitin
• unicell
• no photosynthetic
• no cellulose

Molds

• rapid growth
• hyphae (aerial, vegetative) → mycelium
• spore, sexual, asexual
• Aspergillus, Mucorales, Dermatophytes

Yeasts

• unicell
• threadlike hyphae
• sexually (ascomycetes, basidiomycetes) spore
• asexual (deuteromycetes) binary fission/budding
• Cryptococcus is basidiomycetous yeast (no hyphae)
• Candida, Malassezia

Dimorphic

• Sabouraud agar 25℃ mold
• Brain heart infusion agar + 5% blood 37℃ yeast
• Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Sporothrix schenkii

Uses of fungi

• decomposer
• food
• medicine
• disease causing
• disease fighting
• Fungus-Plant Root Association
• Lichen

Diseases

• mycotoxicosis
• allergic
• colonization & invasion

Culture media

Nonselective

• SDA, Czapek's, PDA
• enriched medium: BHI, +5~10% sheep blood

Selective

• Mycosel, Niger seed, CHROM, Oxgall

Preliminary 

Yeast colony

• smooth
• pasty to mucoid 

Mold colony

• cottony
• velvety
• granular
• powdery

Initial observation

• appearance of the growth 
• surface and reverse surface of colony were observed
• delicate or hairlike hyphae
• rate of growth
• saprophytes: 3~5 d
• dimorphic: >10 d
• dermatophytes: >14 d
• colony pigmentation
• growth on media containing antifungal agents
• most strains of the dimorphic fungi can grow
• most strains of rapidly growing saprobes are inhibited
• dimorphic growth
• mold (environmental and infective form) ambient or room temp 22~25℃
• yeast (invasive form) near body temp 30~35℃

Morphological characterization

• based on anamorphic phase
• variety of reproductive asexual propagules
• conidia/sporangiospores
• variety of hyphael types
• hyaline/pigmented
• septate/aseptate
• texture of thallus
• cottony, velvety, granular, glabrous
• topography of thallus
• rugose, umbonate, verrucose
• color of thallus
• top and reverse

True mycoses: coccidioidomycosis, histoplasmosis

Systemic mycoses

Inhalation of spores 

Coccidioidomycosis

• Coccidioides immitis
• Sputum, tissue
• Direct exam: KOH, H&E, spherule
• Culture: SDA
• Serology: tube precipitin (IgM) test, complement fixation
• Skin test: 25 arthroconidia, 37 spherules

Histoplasmosis

Cave disease 

• Histoplasma capsulatum
• Sputum, tissue, BM, CSF, blood
• Direct exam: Giemsa, Wright
• Serology: complement fixation
• Culture: 25 mold, 37 enriched medium yeast 
• Skin test

Blastomycosis

• Blastomyces dermatitidis 
• Sputum, tissue 
• Direct exam: KOH, H&E
• Culture
• Serology: immunodiffusion test, ELISA
• Skin test 

Opportunistic mycoses 

Cryptococcosis 

• Cryptococcus neoformans 
• Inhalation
• Natural reservoir: bird droppings 
• CSF, sputum, aspirate 
• Direct exam: India ink
• Culture: SDA creamy mucoid
• Serology: latex agglutination 

Aspergillosis

• Aspergillus fumigatus
• Inhalation of spores (conidia)
• Natural reservoir: air, soil 
• Sputum, BAL, lung biopsy
• Direct exam: KOH calcuflour 
• Culture: SDA no cycloheximide 
• Serology: ELISA, RAST

Candidiasis 

• Candida albicans
• Round, oval yeast cells 
• White, pasty, colony, yeasty odor 
• NF of oral cavity, genitalia, large intestine, skin
• Vulvovaginal: low pH, white plaques
• Oropharyngeal: thrush  
• Chronic mucocutaneous: skin, nail
• Mother to infant, childbirth
• Child to mother, breastfeeding
• Sexual
• Nosocomial
• Direct exam: pseudohyphae, true hyphae, yeast cells 
• Culture: SDA creamy
• Germ tube identification
• Serology: ELISA, IF, RIA, latex agglutination
• CHROM agar green color