Mycology

Mycology

Structure

• Cell wall: chitin

• Cell membrane: ergosterol

• Exception: Pneumocystis lacks ergosterol

• β 1 -3 glycan present
• CAP
• Candida
• Aspergillus
• Pneumocystitis jerovicii

Morphological Classification

• Mnemonic: Body Heat Probably Changes Shape

Stains in Mycology

• Culture media:
• Sabouraud dextrose agar (pH 5.6) + gentamicin + chloramphenicol

• LPCB stain + glycerol for hydration

Classification of Mycoses

• Superficial mycosis → Malassezia, Dermatophytes

• Subcutaneous mycosis → Mycetoma, Rhinosporidiosis, Chromoblastomycosis, Sporotrichosis

• Systemic/Deep mycosis

Superficial Mycoses

Fungal infections

• Can be:
• Cutaneous
• Subcutaneous
• Superficial

Dermatophytes (Tineasis/Ringworm)

 

• Nature: Most common fungal infection

• Genera: Epidermophyton, Microsporum, Trichophyton

Affected Areas:

• TME: skin involved in all
• Trichophyton → skin, hair, nails
• Tri → 3 involved 
• Microsporum → skin, hair
• Micro → micro hair involved
• Epidermophyton → skin, nails
• Epidermo - skin & nail

• TME PSC

Classification by Site (Tinea Names):

Classical Presentation:

• Erythematous, annular lesion

• Periphery: Scaling, crusting, or vesicles

• Classic feature: Central clearing

Treatment:

• Topical antifungal (azoles), itraconazole, terbinafine

• Tinea capitis: Oral griseofulvin = DOC

Dermatophytide/ID reaction:

• Sterile lesions away from original site

• Due to fungal products / following antifungal therapy

1. Tinea versicolor (Malassezia furfur)

• Mnemonic: Buy Mala for her (Malassezia furfur) → Global (Globosa)
• Adolescents (in adolescents) give Mala
• Acid veenal (Azelaic acid/carboxylic acid) → Mala lose its color → hypopigment
• With Giant money (Giant melanosomes) → Colorful maala → hyperpigmented
• Then she will make you
• Sphagetti and meatball ()
• Banana and grape juice ()
• But he has 2 face (Dimorphic)

• Nature: Common superficial infection

• Nomenclature: "Tinea Versicolor" is a misnomer
• Tinea implies dermatophytic
• Caused by yeast

• Cause: Malassezia yeast
• Species:
• M. globosa (most common)
• M. furfur
• M. sympodialis

• Predisposing Factors: Hot, humid weather

• Demographics: Adolescents

Clinical Features:

• Asymptomatic, recurring lesions

• "Pityriasis": scaly

• "Versicolor": varying colors

Presentation:

• Hypo- or hyperpigmented macules

• On trunk

• Fine/branny scales (characteristic)

• Pigmentation cause:
• Hypopigmentation: carboxylic/azelaic acid
• Hyperpigmentation: giant melanosomes

Note

Typical Lesion	Seen in
Silvery white	• Psoriasis
Lacy white on mouth	• Lichen Planus
Greasy	• Seborrheic dermatitis
Fish-like	• Ichthyosis vulgaris
Collarette	• Pityriasis rosea • collarette of rose
Fine/Branny	• Pityriasis versicolor • Bra of different colors
Burrow	• Scabies
Comedones	• Acne
Target lesion	• Erythema multiforme

Investigations:

• KOH Smear: Dimorphic fungus
• 10% KOH skin scraping → keratin digestion
• Yeast form + hyphal form
• Classic appearance: "Spaghetti and meatball" or "Banana and grapes"

• Culture: SDA with olive oil (lipophilic)
• Fried egg colonies

• Wood's Lamp: Yellowish fluorescence

Mnemonic:

• NO (9% Nickel oxide) Bullshit (Barium silicate) in Woods

• 365 days (365nm) in wood

• Woman with green cap (tinea capitis green), yellow beaded pedant (yellow versicolor) around neck and red bikini (red → erythrasma) inside a forest full of wood (Woods lamp)

Treatment:

• Topical:
• 10% sulphur ointment, 1–2% imidazole cream
• Azoles:
• Clotrimazole, Sertaconazole, Luliconazole
• Non-azoles:
• Zinc pyrithione, selenium sulphide, sulphur

• Oral (severe):
• Fluconazole, Itraconazole
• Only if recurrences

2. Tinea Nigra

 

• Brown patches on palms/soles

• Organism: Hortaea werneckii

• Treatment: Topical imidazole

• Brown () nigro () is hot (Hortae)

3. Piedra

• Presentation: Hair shaft nodules

Types:

• Treatment: Topical imidazole, shaving hair

• Mnemonic: Pee
• Black people → show hard (hort (P. hortae)) scalp (scalp seen) (mottathala) → are hot (Horta)
• white people → show soft dick→ tried- asahaniyam (asahi, nodosa) / Biglii (white lightening)

Tinea Capitis

• Affected Area: Scalp or hair

Clinical Types:

• Inflammatory:
• Scarring seen
• Kerion, Favus

• Non-inflammatory:
• Hair Shaft Involvement:
• Endothrix:
• Fungal hyphae inside hair shaft
• Black Dot
• Ectothrix:
• Fungal infection outside hair shaft
• Grey Patch

Non-Inflammatory Types:

 

Inflammatory Types:

• Usually caused by zoonotic species

Treatment of Tinea Capitis:

• Always Oral (topical only for preventing spread)

• Drug of Choice: Griseofulvin

• Other agents: Terbinafine, Itraconazole

Hair perforation test:

• Differentiates T. rubrum vs T. mentagrophytes

• T. mentagrophytes → hair shaft erosion

Tinea Corporis

• Affected Area: Body

• Most Common Organism: 
• T. mentagrophytes

Variant:

• Tinea Circinata:



• Appearance: Concentric rings of fungal infection
• Cause: T. concentricum

Tinea Pedis (Athlete's Foot)

• AKA: Athlete's Foot (prone due to sweating, running)

• Affected Area: Feet (dorsal aspect)

• Most Common Involvement: 
• Interdigital fourth web space

Tinea Cruris (Dhobi Itch / Jogger's Itch)

• Affected Area: Crural folds (moisture, sweat)

• Alternative Names: 
• Dhobi Itch, Jogger's Itch

• Clinical Features:
• Less scales, more erythematous plaques (due to maceration)

Tinea Incognito

• Nature: "Hidden" - atypical classical tinea

• Typical History:
• Itchy rash treated with OTC steroids
• Improves inflammation, not fungus
• Relapses, atypical presentation

• Appearance:
• Not classical;
• small, scattered erythematous papules or pustules

• Treatment:
• Same as other tinea
• severity-dependent, usually oral

Tinea Unguium / Onychomycosis

• Onychomycosis:
• fungal nail infection
• Causes: Dermatophytes, Candida, other moulds

Clinical Presentations (Four):

1. Distal Lateral Subungual Onychomycosis (DLSO): 
• Most common

2. Proximal Subungual Onychomycosis (PSO):
• Whitish band proximally,
• often in HIV patients

3. Superficial White Onychomycosis (SWO):
• White patches, scrapeable

4. Total Dystrophic Onychomycosis (TDO):
• Total nail dystrophy

General Appearance:

• Usually asymptomatic

• Whitish nail discoloration,

• subungual hyperkeratosis,

• total dystrophy

Differentiation from Psoriatic Nail:

Treatment:

• Topical Nail Lacquers:
• Ciclopirox olamine, Luliconazole, Amorolfine (morpholine)
• Mnemonic: Cycle (ciclopirox) il Lulu (luliconazole) yil poi → nail lacquer () vangan→ amalnodu (amorolfine) prnju

• Systemic Medicines (most common):
• Terbinafine: 250 mg daily
• Fingernails: 1.5 months
• Toenails: 3 months
• Itraconazole:
• Daily Therapy: 100 mg BID
• Fingernails: 2 months
• Toenails: 3 months
• Pulse Therapy: 200 mg BID for one week /month
• Fingernails: 2 pulses
• Toenails: 4 pulses

• General Investigation (Dermatophytic Infections):
• KOH smear: Branching, septate hyphae

Subcutaneous Mycoses (Mnemonic – MRCS)

• Deep infections, usually via inoculation

• Three Main Types:
• Mnemonic: MRCS
1. Mycetoma
2. Rhinosporidiosis
3. Chromoblastomycosis
4. Sporotrichosis

Mycetoma

Alternative Names: 

• Madura Foot

• Maduromycosis

Types:

• Eumycetoma: Fungal cause

• Actinomycetoma: Bacterial cause

• AB EF→ Actinomycetoma-bacteria, eumycetoma-Fungal

Key Differences (Types):

Most Common Eumycetoma Cause: 

• Madurella mycetomatis

Eumycetoma (typically foot):

• Caused by fungus

• Usually painless

• Classic Triad:
1. Tumefaction (swelling/induration)
2. Multiple Discharging sinuses
3. Grains (gritty fungal colonies)

• Can cause deformities

• Granule colors:
• Brown → Madurella mycetomatis
• Red → Actinomadura pelletieri
• White/Yellow → Nocardia, Streptomyces, Actinomadura

• Antifungals
• If failed → or amputation

• Microscopy:
• Sunray appearance
• Blue filaments on Gram stain

Actinomycetoma (bacteria):

• Actinomadura madurae

• Gram +ve filamentous bacteria

• Treatment:
• Cotrimoxazole ± amikacin (6–12 months)
• Dapsone
• Streptomycin
• Co-trimoxazole
• Rifampicin

Rhinosporidiosis

• Organism: Rhinosporidium seeberi

• Aquatic parasite, history of swimming (South India)

• Mulberry nose

• Site: Nasal cavity

• Gross: Strawberry polyp

• Microscopy: Sporangia with endospores

• Non-cultivable organism

• Treatment: Excision + Dapsone

 

Chromoblastomycosis

• Nature: "Chromo" (coloured), "Blastomycosis" (raised, verrucous)

• Source: Traumatic penetration (barefoot walking)

• Causative Organism: 
• Phialophora verrucosa
• Fonsecaea pedrosi, F. compacta, Exophiala, Cladophialophora
• Rhinocladiella aquaspersa
• Carrioni

• Presentation: 
• Verrucous dermatitis (warty lesion)

• Fungal Characteristic: 
• Pigmented fungus
• Diamatiticiaeous fungus
• Give brown to black colour due to melanin in cell wall

• Staining (Histopathology): 
• Sclerotic
• Muriform, Medlar
• Copper penny" bodies 
• pigmented, multi-planar dividing fungus

• Treatment: Wide surgical resection, laser, Amphotericin B

• We will spend copper (copper penny) coins to eat multicoloured () drugs

Sporotrichosis

• Most common subcutaneous fungal question

• subcutaneous mycosis +dimorphic

• Mnemonic:
1. Got attacked by Spines in rose garden
2. Sporotrichosis → Splendid life →
• Splendor (splendor hoppeli) indu
• lies on rose garden (rose gardners disease),
• rosettes (rosettes of conidia) present
• Stars (asteroid) in sky, cigar (cigar body) in hand

• Alternative Name: Rose Gardener's Disease/ lymphocutaneous disease

• Typical History:
• Farmer, rose garden (thorn prick)
• Source: Traumatic prick (rose thorn)

• Organism: Sporothrix schenckii

• Presentation:
• Spread: Nodules along lymphatics
• Lesions in linear/sporotrichoid pattern along lymphatics
• Erythematous papules/nodules, possible crusting

Histopathology:

• Rosette of conidia

• Often asteroid bodies 
• Asteroid body → Round cigar-shaped fungus + Splendore-Hoeppli
• Asteroid bodies
• extracellular → Sporothrix
• intracellular → Sarcoidosis

• PAS stain: 
• Cigar-shaped bodies

Treatment:

• Potassium iodide (KI)

• Itraconazole or

• Terbinafine (KI or Itraconazole preferred)

Dimorphic Fungi

1. Blastomyces

• Disease: North American/Chicago/Gilchrist blastomycosis

• Morphology: Broad-based budding (8-shaped)

• Treatment:
• Mild → Fluconazole/Itraconazole
• Disseminated → Amphotericin B + Itraconazole

2. Histoplasmosis

• Disease: Ohio/Darling/Cave disease/Missisipi

• Infection: Reticuloendotheliosis, inside macrophages

• Reservoir: Bat/bird droppings, soil

• Mimics TB

• ID: Yeast 2–4 µm; tuberculate macroconidia in LPCB on SDA

• Treatment
• Amphotericin B
• Itraconazole - maintenance

3. Paracoccidioidomycosis

• Disease: South American blastomycosis

• ID Morphology: Pilot wheel / Mariner wheel / Mickey Mouse appearance

4. Penicillium (Talaromyces) marneffei

• Reservoir: Bamboo rat

• LPCB → brush/broom morphology

• Produces red pigment

• Marna rat () with a broom () till red ()

5. Coccidioidomycosis

• Mnemonic: ABCD → America, Barrel-shaped spores, California, Desert

• Disease: Desert rheumatism / valley fever / California disease

• Characteristic: Joint involvement

• Microscopy: Spherule with endospores

• Spores: Barrel-shaped arthrospores (LPCB)

Opportunistic Infections

Cryptococcus Neoformans

• New world
• Pigeon droppings + Immunodeficient people
• Easily treatable
• + Negative (India ink) Music (Mucicarmine)

• Old world → Gatti
• Trees (eucalyptus tree) with leaf (LFA) and latex
• immunocompetent + Immunodeficient people
• Tropical climate
• difficult to treat diseases

Clinical features

• Fever, headache, photophobia, vomiting, nuchal rigidity.

• Seen in immunocompromised,
• e.g. AIDS truck driver.

Workup

• First:
• Blood culture,
• start empiric antibiotics in 1 hr.

• Empiric:
• Ceftriaxone + vancomycin (no cryptococcal coverage).

• NCCT:
• Check raised ICP.

• Brain biopsy:
• In dead
• Mucicarmine

• CD4 <100 needed for disease.

LP:

• CSF cell counts.
• Lymphocytic pleocytosis.

• Slightly reduced sugar, high protein (norm: 15–45 mg%)

• Gram: No organism.

• CSF ELISA (Ag) is IOC.

• India ink / Nigrosin:
• Positive > Negative (not reliable).

Culture

• Agar: Bird seed / Niger seed agar

• Colour: Brownish due to Phenol Oxidase / Laccase

Confirmatory Test

• Lateral flow assay > latex agglutination
• Lateral flow assay ⇒ cryptococcal antigen
• Serum/plasma/CSF.
• More sensitive and specific
• Latex agglutination ⇒ Glucuronoxylomannan

• Cryptococcus found in pigeon droppings, dust.
• Healthy:
• No CNS disease due to immunity.
• Immunosuppressed:
• Lung → brain (via blood)

Treatment

• Amphotericin B >> (+) flucytosine
• Not LAMB (For Kala azar)

• Prevention/Maintenance
• Fluconazole (when CD4 < 100)

Candida

• Causative Agents: Candida species

• Predisposing Factors: 
• Immunocompromised, pregnancy, diabetics

• Affected Areas:
• Skin, nails, mucosa (does not affect hair)

• Morphology: Yeast-like

Species and Features

• Cruisers (krisei) has Aura (auris) → and are resistant

• Control the kafir

Oral Candidiasis (mucosa):

• Presentation:
• Whitish patches,
• difficulty eating/spices

Types:

• Oral Thrush / Acute Pseudomembranous Candidiasis:
• Whitish plaque, 
• easily scraped off
• Mnemonic: Candida → Can be scraped offf

• Chronic Plaque (Candidal Leukoplakia):
• Thick plaque, 
• cannot be scraped off (premalignant)

• Acute Erythematous Candidiasis 
• "Antibiotic Sore Throat":
• Erythematous patches after antibiotic use

• Chronic Erythematous (erythoplakia) Candidiasis/ Chronic Atrophic Candidiasis
• With dentures
• Does not have a white patch

• Angular cheilitis/perleche

Genital Mucosa:

• Vulvovaginal Candidiasis (females)

• Candidal Balanoposthitis (males): 
• Satellite lesions (small vesicles)
• small erosions with "frayed edges"
• Splash dysuria
• Common in diabetics, uncircumcised

Intertrigo (skin folds):

• Appearance: 
• Satellite lesions
• frayed peeling edges
• concave surface

• Mnemonic:
• Candida → splash dysuria
• Candida → pattern like splashed → satellite lesions with peeling/frayed edges

• Differentiation:
• Satellite lesions & frayed edges distinguish from Tinea

Investigations

• Curdy white discharge

• On PAP smear:
• "Sheesh Kebab effect"

• Cells in line → Pseudohyphae

• CHROM agar
• Differentiate between candida

• KOH Smear:
• Budding yeast cells

• Culture:
• Colonies: Creamy white / Pasty / Yeasty in SDA

Growth / Identification

• Corn Meal Agar → Chlamydospores

• Germ tube test
• Specific for Candida albicans
• Reynold Braude Phenomenon
• Albicans + serum (at 37 degree C x 90 mins) ⇒ True hyphae

Treatment: 

• Only azoles (topical or systemic)

• Allylamines, Griseofulvin NOT USED

Aspergillus

• Hyphae: Septate

• Branching: Acute angle, dichotomous (<90°)

• Forms and Colour
• A. fumigatus: Smoky green, conidia on upper vesicle
• A. flavus: Green & yellow, conidia all over
• A. niger: Black





 

Features

• Halo sign in CT

• Invasive aspergillosis → Galactomannan positive

• ELISA
• Serum / BAL

Treatment

• May require Surgical resection

• Disseminated infection: Voriconazole

Aspergillus lungs:

• A fungus with septate and acute angle branching hyphae.

• Can cause:
• Allergic Bronchopulmonary aspergillosis (ABPA).
• Aspergilloma.
• Angio invasive aspergillosis.

ABPA:

• Dilated central bronchi filled with mucous - Finger in glove sign.

Aspergilloma:

• Seen when there is a pre existing cavity in the lung.

• Air crescent sign or monod sign.

• Prone CT to confirm aspergilloma:
• fungal ball is mobile
• comes to the dependent position.

Angio Invasive Aspergillosis:

• Central infarct surrounded by GGO - Halo sign.

• i.e. white consolidation surrounded by ground glass opacity.

• Seen in immunocompromised patients.

• Voriconazole

Mucormycosis lungs

• Also called: Black fungus

• Reverse HALO sign (Atoll sign) → centre dark, periphery light

 

• Reverse halo sign on CT

• Neutropenia

• Immunocompromised

• Hyphae: Aseptate, Right angle, Broad, ribbon-like

• Culture:
• Lid-Lifters (SDA)
• May be negative d/t Hyphal fragility (killed by tissue homogenisation)

• Lid lift cheyyumbo mukki povum

• Treatment
• Surgical resection
• Amphotericin B +/- Posaconazole
• Mucus pasha pole - Posaconazole

• Negative Staining Group:
• Blastomyces, Mucorales, Cryptococcus
• Banglore Medical College

Aspergillus nose (Allergic Fungal Rhinosinusitis)

Non Invasive

• Types: Fungal ball, Allergic fungal rhinosinusitis

• Seen in immunocompetent and immunocompromised

• Cause: Aspergillus

• Peanut butter discharge

• Mnemonic: HIV AIDS → Kuninj bent cheythapo sinusitis vann

• Bent and Kuhn criteria for AFRS:
• Major Criteria
• Mnemonic: Mr KUHN
• Test Mucus
• Eosinophilic Mucin
• KOH Fungal smear: Positive

---

• CT scan:
• Hazy sinuses + Heterogeneous opacities
• Double density sign / Serpiginous sign
• Gray mucous with white fungal matter





---

• Endoscope
• Nasal polyps → Ethmoidal polyps more associated
• Serum
• Uno → 1 → Type 1 hypersensitivity (↑IgE levels)
• Minor Criteria
• Mnemonic: CURE AF
• no major features like culture, asthma
• Charcot–Leyden crystals
• Unilateral predominance
• Radiological Bony erosion
• Serum Eosinophilia
• Asthma
• Fungal culture: Positive

• Treatment:
• FESS
• Endoscopic surgical drainage, along with drainage and ventilation.
• Steroids
• Pre- and post-operatively.
• Antifungal therapy: Itraconazole.

Invasive infections

• History of woody injury (+)

• Types:
1. Invasive aspergillosis
2. Invasive mucormycosis

Mucormycosis Nose

• aka Phycomycosis

• Angioinvasive

• Presents with blackish eschar

• Fungal thrombus causes tissue necrosis

• MRI shows Black turbinate sign

• Black turbinate sign:
• Due to necrosis- no enhancement.

• Biopsy
• Foreign body granuloma
• Gomori’s Methanamine Silver stain + PAS positive

• IOC: Contrast enhanced MRI.

• CT: Bony spread.

• Spread: Blood.

Treatment:

• Extensive debridement of tissue.

• Liposomal form of Amphotericin B (lyophilised form is nephrotoxic).

Pneumocystis Carinii (jiroveci)

• Pneumocystis jiroveci

• Has β D glucan in cell wall

• Association: HIV+ patients, CD4 < 200

• Disease: PCP / Plasma cell pneumonia
• Symptoms: Dry cough
• Diagnostic clue: Positive BAL

• Stains
• GMS stain

• Microscopy
• Looks like:
• Helmet / Hat
• Cup and Saucer
• Ping-pong crushed ball
• Represents: Cysts (trophozoites)

• Treatment
• Cotrimoxazole
• Severe cases: Pentamidine

Pneumocystis Carinii Radiology

DRUG	MECHANISM
Azoles	MECHANISM • ⛔ lanosterol 14-α- demethylase • ⛔lanosterol -> ergosterol synthesis USE • DOC for Candidasis ↳ Fluconazole. • DOC for Invasive Aspergillosis ↳ Voriconazole Very (Voriconazole) Invasive Aspergillosis Azole → assholes → dont knw how to cross lane (lanosterol) Lanosterol - ergosterol
Amphotericin B & Nystatin	MECHANISM • Bind to ergosterol and create pores USE • Mucormycosis (DOC). • Cryptococcal meningitis (DOC). • Kala azar (DOC - LAMB). LAMB → muttanaadu (mucor) → idichu thorannu Pore (create pore) idakki → Cryptil keri Cryptil (Cryptococcal) kidannu Karuthu (Kala azar) Poi
Allylamines / Terbinafine	MECHANISM • ⛔squalene epoxidase • ⛔lanosterol -> squalene conversion USE • Dermatophytosis (DOC). Tera bina () → sqeeze (squalene) hogaya → dermat fight () hogaya
Griseofulvin	MECHANISM • ⛔mitotic spindle USE • Dermatophytosis → Tinea capitis ("spindle il grease ozhich karakkam")
5-Flucytosine	MECHANISM • ⛔ Fungal DNA Polymerase USE • With AMB for cryptococcal meningitis CAUTION • Not given with Alcohol • Disulfiram like reaction
Caspofungin (Echinocandins)	MECHANISM • ⛔ β glucan synthesis • Cell wall inhibitor USE • Systemic Candidasis ↳ Initial treatment ↳ Not Nephrotoxic • Aspergillosis CAspo → Candida and Aspergillo - inhibit candy

Notes	Antifungals
Azole useful in mucor	Posaconazole / Isavuconazole
Azole with antipruritc/ anti-inflammatory action	Sertaconazole
Antifungal causing heart failure	Itraconazole

Itraconazole

• DOC
• Histoplasmosis
• Sporothrix
• Blastomyces

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AMB

• Side effects
• Nephrotoxic
• Liposomal AMB is less nephrotoxic.
• (Cryptococcal, Mucor uses AMP)
• Infusion reaction
• RTA type 1
• Hypokalemia
• BM suppression

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Voriconazole

• Take on an empty stomach
• (also for ATT drugs)
• Fatty meals ↓ absorption

• Metabolized by cytochrome P450 enzymes

• Transient visual changes

• Monitor blood levels
• Especially in liver disease
• Helps titrate dosage

• Avoid combination with pyrazinamide

• DOC for Aspergillus