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L22&23 - Funghi Understand the thallus as a Eukaryotic cell …
L22&23 - Funghi
Understand the thallus as a Eukaryotic cell
Understand that funghi can be a yeast or mould => hypha = mycelium - example of each
Meaning of Dimorphc fungus (exist as both yeast and mould) - example of dimorphism
Basic Fungal structures - compare and contrast different spore morphologies
Clinical classification of fungal diseases
Sites of infection and appearances of these fungal infections
Deeper understanding of CANDIDIASIS in immunocompromised hosts + risk factors.
Deeper understading of dermatophytes
Fungi - Structural Features
MOULDS:
Hypha = trunk
Hypha may be segmented by Septum
Hypha = Aerial or Subsurface
Conidia = leaves (spores on hypha/trunk)
- Thallus
The fungal cellular unit
- Cell Wall
Microfibrils composed of
chitin
**
- Intracellular Microtubules
Composed of tubulin
Chromosome movement during
cell division
- Cell Membrane
contaisn
ergoserol
(equivalent to human cholestrol - flexibility and strength)
- Smooth + Rough ER
Ribosomes
- Mitochodria
Subcutaneous Mycoses
Dermis & Subcutaneous tissues =>
muscle
and
fascia
(fascia - attach, separate, connect and stabilise internal organs and muscles)
Dematiaceous fungi
- melanin in hypha (saprobes = phaehyphomycosis) and cause
eumycotic mycetomas
Found in soil + decaying vegetation =>
traumatic implantation
Eumycotic Mycetoma
(maduromycosis)
Madura foot
Causative species
Not expected to know
Pseudallescheria
Madurella
Exophila
Acremonium
Leptosphaeria
Curvularia
Fusarium
Symtpoms
Pus production and secretion of "grainy" fungal colonies
Destroys muscle, fascia, tendons and bones
IMPLANTATION => Subcutaneous swelling -> months/years -> deeper tissues
IMPANTATION
Chromoblastomycosis
Symptoms
IMPLANTATION - Initial lesion - small elevated patch
New appearace of reddish-purple patches
Pseudoepitheliomatous hyperplasia
Huge cauliflower like masses
Causative species
Cladosporium carrionii
Fonsecaea
Phialophoria
Phaehyphomycosis
Dematiaceous saprobes = Agents of phaehyphomycosis = derive nutrients from non-organic/decaying matter through hyphae
Symptomatic Manifestations
IMPLANTATION
Subcutaneous Infection
Cystlike lesions/verrucos (warty) appearance in immunocompromised
Some forms infect nasal sinus and/or brain
Invades Orbital - then brain
Causative Species
Don't need to now
Exophiala jeanselmei
Wangiella dermatitidis
Sporotrichosis
More likey to be encountered in WA
May also be caused by
=> other fungi
=>
Nocardia brasiliensis
=>
Mycobacterium marinum
Causative specimen
Sporothrix schenkii
DIIMORPHIC
Symptoms
Occasional misdiagnosis for
Staphylococcus aureus
INOCULATION
Nodular lesion
Ulceration
Chonic Ulcer
Potential to disseminate into regional lymphatic
Suppurative Abscesses
Opportunistic Mycoses
Cause disease in those with impaired immunity
Non-pathogenic in healthy hosts
Hyaline saprobes are included (differe from dematiaceous because lack melanin)
Candidiosis
May be carried as a commensal to mucosa of oropharynx and vagina
Manifestations in immunocompromised host
Chemotherpay
AIDS
Cancer
Extensive muco-cutaneous lesions + deep organ infectin
Oral Cadidiasis (thrush)
Usual manifestation secondary to localised/systemic immune suppression
Indication of underlying disease
Vaginal > Oral
Symptoms
Aherent white plaque => raw/bleeding/painful when scraped off
Oesophageal Candidiasis
Inidcation of severe immunosuppression
Signs & Symptoms
Feeling of obstruction when swallowing
Substernal chest pain
Dysphagia
Painful Swallowing
Nausea vomiting
Adherent plaque causes erosion
Candidaemia
Candida
multiplying in the blood stream
Associated with 40% mortality
Risk factors
antibiotic use - weakens commensals
contaminated IV cannula
debilitation/surgery/immunosuppression
Concurrent muco-cutaneous candidiasis
Symptoms & Signs
Febrile
Ubiquitous skin nodules
haematogenous dissemination to cutaneous tissue
Complications
Dissemination and groeth in deep organs may occur silently = progress asymptomatically
Occular Candidiasis
Occurs in ~25%
White cotton wool lesions in retina
=> Endopthalmitis
Permanent blindness
Candida Endocarditis/myocarditis
Associated with
=> cardiac surgery (
prosthetic valve
)
=> heroin addiction (contaminated)
Musculoskeletal candidiasis
Osteomyelitis
Heptosplenic candidiasis
Manifestations in immunocompetent Host
Muco-cutaneous infection in healthy individuals
Aspergillosis
-
Aspergillus spp.
Ubiquitous in the environ (comp., hair etc.)
=> Inhaled quotidiennement
Disseminated Aspergillosis
Severely IMUNOCOMPROMISED HOSTS (burns)
Original site of infection =
lung > intravenous lines/burns/sinuses
HIGH MORTALITY
Slide 28-29
Aspergillosis of paranasal sinuses
Non-Invasive Form
Poorly draining sinues => chronic SINUSITIS
Invasive Form
Immunocompromised
=> Febrile, rhinitis (runny nose => invades orbit
Pulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis
Hypersensitivity to inhaled condia (spores [leaves] hypha [branch])
pre-existing astham/cystic fibrosis...
Episodic wheeze = > brown sputum => irreversible lung damage =.
pulmonary fibrosis/bronchiectasis
Aspergilloma
fungus ball (
tangled mycelia
)
Erode nearby structures =>
Haemoptysis - invasion of artery
Invasive Pulmonary Aspergillosis
Severely IMUNOCOMPROMISED HOSTS
Necrotising pneumonia (
Klebsiella pneumoniae
)
Disseminate septic emboli to other organs
Cutaneous Aspergillosis
Immunocompromised Patients
Disseminated from other source =>
erythematous macules + necrotising centre
Hyalohyphomycosis
(Opportunistic infections
Causative Species
-
Hyaline Hyphomycetes
=>
mycelia is clear
, as opposed to the brown pigmented mycelia of the dematiaceous hyphomycetes
Environmental saprobes
= uncommon human pathogens
Acremonium
Fusarium
Paecilomyces
Penicillium
Scedosporium
Scopulariopsis
Clinical Manifestations
Mycotic keratitis (corneal inf.)
Skin infection => cellulitis, mycetoma
Onchyomycosis (like tinea unguium)
Fungaemia - disseminated inf.
Zygomycosis
mucormycosis
Ubiquitous environmental funghi
Rare = SEVRE IMMUNOCOMPROMISED
Causative Species
(Zygomycetes)
Feared species = infect
rhino-facial-cerebral
area and can extend to brain
Absidia
Mucor
Rhizopus
Clinical Manifestations
Sinusitis
Rapid invasion
Bloody nasal discharge + swelling cheek
Invasion of orbit => brain
Rapidly fatal
Proptosis (forward displacement of the eye)
Headache
Confusuion
Coma
Deep Seated Mycoses
Adequately virulent to cause systemic infection of healthy or immunosuppressed host =>
Truly pathogenic
Dimorphic
fungi (except
Cryptococcus neoformans
)
Mycelial
= interwoven hypha
Occurs in mould form
Yeast
= unformed hyphae
Cryptococcosis
Cause of disease wighin Perth/Australia locality
Causative species
=> These are encapsulated yeasts
=> Ubiquitous in nature
Cryptcoccous gattii
Particular eucalyptus trees
Cryptococcous neoformans
Pidgeon droppings
India Ink preparation
Clinical Manifestations
Acquired by Inhalation
Most contractions = ASYMPTOMATIC
Immunocompromised infection > immunocompetent
AIDS
Chemotherapy
etc
Pulmonary Cryptoccous
Usually spontaneous resolution
-Chest pain
=> Dense infiltrates on CXR
=> Asymptomatic/Symptomatic infections => Cerebral dissemination
CNS Cryptococcous
Meningoenkephalitis
(Like viral enteropathogens)
Acute/insidious onset
=> Headache/nausea
=> Irritability/confusion/dementia
=> Staggering gait
=> Cranial nerve palsies
Cutaneous Cryptococcous
Isolated infection - primary site of inoculation
Disseminated infection = original pulmonary infection
Geographically isolated D.S. Mycoses
Dimorphic fungi
Shelve in the back of brain
Coccidioidomycosis
Coccidioides immitis
Southwest USA
Primary Pulmonary Disease + disseminated inf. in AIDS patients
Paracoccidioidomycosis
Paracoccidioides brasiliensis
Central and South America
Pulmonary Infection
=> Rarely disseminated infection
Histoplasmosis
Histoplasma capsulatum
Ohio, Missouri and Mississippi rivers + Isolated in Euro + Africa
Minor respiratory diease + Occasionally flu-like disease + Disseminated infection in AIDS patients
Blastomycosis
Blastomyces dermatitidis
USA + Canada + South Africa
Pulmonary Infection + Chronic granulomatous skin disease
Superficial and Cutaneous Mycoses
Superficial
= limited to outermost layers of skin and hair shafts
Cutaneous
= extend deeper into epidermis - includes invasive hair and nail infections
Pityriasis versicolor
Superficial mycosis
Causative specimen
Malassezia furfur
Pale flaky patches on the skin (trunk, neck, arms)
Appear coppery on pale skin
Appear lght on dark/tanned skin
Infection of superficial keratin layer
Dermatophytosis
Cutaneous(tinea=ringworm)
Causative Species
Microsporum spp.
Trichophyton spp.
Epidermophyton floccosum
Tinea circinata
Annular lesion - raised inflammed edges, dry scaly centre
Onchyomycosis = tinea unguium
Candidiasis
Muco-cutaneous (usually)
Causative species
Candida spp.
Also considered opportunistic & deep seated
Reproduce by budding
May be found as yeasts, hyphae or pseudohyphae
(not considered dimorphic)
Encountered mostly in
mucosal membranes, skin + nails
Candida albicans
Non-albicans Candidas
Many opportunisic pathogens
C.auris
an emerging pathogen
Candida glabrata
Symptoms
Candidiasis Infection
-Skin + mucosal infection due to;
=> Disturbance of commensal flora (antibiotics
White discharge = curd-like ad adherent
=> Damaged/moist skin
=> Immunocompromised (diabetes)
