Mycology Lecture 2 + Lab Basics

Front 1

Define hyphae

Back 1

Long strands of cells which may form mats like mycelium

Front 2

What is the appearance of asceptate hyphae? Give an example of a group with asceptic hyphae

Back 2

- contain no cross walls
- seen in Zygomycotina
-

Front 3

Describe septate hyphae. Give an example of a group with this hyphae.

Back 3

- most hyphae are septate
- Ascomycotina
- Basidiomycotina
- Deuteromycotina

Front 4

Define conidia

Back 4

reproductive structures often seen on the end of aerial hyphae

Front 5

Define superficial mycoses

Back 5

- Top keratin-containing layers of skin or hair.
- Non-invasive
- Sometimes described as 'basically asymptomatic'

Front 6

Define cutaneous infections

Back 6

- deeper epidermal layers of skin, nails and hair,
- produces more tissue destruction and symptoms than superficial.

Front 7

What are the four superficial mycoses?

Back 7

tinea nigra
Pityriasis versicolor
Black piedra
White Piedra

Front 8

What is the organism responsible for Black Piedra?

Back 8

Front 9

What is the organism responsible for white piedra?

Back 9

trichosporon ovoides

Front 10

Give examples of cutaneous infections in humans

Back 10

Dermato- phytosis
Dermato-mycosis
Candidiasis

Front 11

What are the causative agents of Dermatophytosis

Back 11

Tricho-phyton spp.
Epidermo-phyton sp.
Microsporum sp.

Front 12

What is Dermatomycosis

Back 12

a cutaneous mycoses caused by fungi other than dermatophytes

Front 13

List dermatophytes

Back 13

trichophyton
epidermosphyton
microsporum

Front 14

What is the causative agent of the mycosis Candidiasis

Back 14

Candidia spp.

Front 15

What are the two types of specimens in the mycology lab? what types of specimens are in this group?

Back 15

1. cutaneous and keratinised tissue (3)
-skin, hair, nails
2. non keratinised subcutaneous and systemic specimen (6)
- tissue bx
- blood,
- sputum,
- urine,
- CSF,
- bronchial washing

Front 16

What is performed on all specimens. What is rate limiting step in clinical specimens?

Back 16

- Microscopy and culture is performed on all specimens as direct microscopy does not rule out disease.
- enough specimen material

Front 17

How is isolation media and direct microscopy performed?

Back 17

guided by specimen types - same as bacteriology

Front 18

What are the factors which determine whether or not the isolation of fungi is successful?

Back 18

1. proper collection
2. quick transport, quick processing
3. appropriate media
4. correct incubation conditions

Front 19

What is the Most rapid method for diagnosis?

Back 19

- microscopic examination of material

Front 20

what are the mounting fluids for clinical materials composed of?

Back 20

- 10% potassium hydroxide
- 10% KOH and glycerol
- (UV) 10% KOH, glycerol and calcoflour white

Front 21

How is collection performed for superficial and cutaneous infections?

Back 21

from actively growing outer edge of lesion

Front 22

How is collection performed for scalp infection

Back 22

15-20 hair roots for collection
- due to infection being in the roots
- spores are around hair and inside

Front 23

How is collection performed for nails?

Back 23

scrape inside of nail and close to nail bed, while removing as much diseased tissue as possible

Front 24

How is collection performed for feet?

Back 24

Discard outer horny layer and scrape lower layer
also sample between 4th and 5th toes.

Front 25

How is collection performed for tinea

Back 25

Discard outer horny layer and scrape lower layer
also sample between 4th and 5th toes.

Front 26

What is the specimen collection procedure for skin scrapings

Back 26

- alcohol swab
- advancing border sample
- rolling of swab over lesions

Front 27

What is the specimen collection procedure for hair samples

Back 27

pluck from shaft

Front 28

What is the specimen collection procedure for nail samples

Back 28

alcohol
deep scrape to sample tissue recently invaded.

Front 29

What is the turnover time for microscopy?

Back 29

<24hrs

Front 30

What is the turn around time for culture?

Back 30

1-4 weeks

Front 31

What are the likely dx for tinea?

Back 31

TEM
Trichophyton
epidermophyton
microsporum

Front 32

What are possible dx for systemic pathogens?

Back 32

Fusarium
Scedosporium

Front 33

What are the three dermatophyte genera?

Back 33

TEM

Front 34

How can dermatophyte genera be made distinct from one another?

Back 34

TEM

Front 35

Which of the three genera of dermatophytes can infect nails?

Back 35

Trichophyton

Front 36

Describe the shape and cells in each of the dermatophyte genera

Back 36

Front 37

Which genera in dermatophytes have thick walls?

Back 37

Microsporum can have thick or thin walls.

Front 38

Which dermatophyte has macroconidia shaped like a
(a) pencil
(b) eliptical/spindle
(c) club

Back 38

trichophyton
microsporum
epidermophyton

Front 39

Define arthrophilic and an example of such an infection

Back 39

Trichophyton rubrum
only affecting parastisim in humans

Front 40

What are zoophilic infections? give an example

Back 40

human infection is from contact with animals. an exampls is microsporum canis

Front 41

What is a geophilic infection? give an example

Back 41

an infection transferred through soil or contact with soil. Microsporum gypseum is an example.

Front 42

Explain host specificity - give an example

Back 42

T. concentricum Infections among Europeans are rare. Distribution is restricted to the Pacific Islands of Oceania, South East Asia and Central and South America.

Front 43

How do we diagnose dermatophytes?

Back 43

Use calcofluor white + 10% KOH
OR --> KOH + Parker ink

look for septae and arthroconidia in skin & nails
look for spores and hyphae in hair roots

Front 44

define ectothrix

Back 44

Endothrix refers to dermatophyte infections of the hair that invade the hair shaft and internalize into the hair cell. This is in contrast to exothrix (ectothrix), where a dermatophyte infection remains confined to the hair surface

Front 45

define endothrix

Back 45

Endothrix refers to dermatophyte infections of the hair that invade the hair shaft and internalize into the hair cell. This is in contrast to exothrix (ectothrix), where a dermatophyte infection remains confined to the hair surface

Front 46

Why is microscopy so important in fungi?

Back 46

1. In case it was zygomycosis or cryptococcus
2. Some organisms do not grow in culture
3. will direct the selection of primary isolation media - special media or additional specimens
4. Helps determine the significance when it does grow in culture

Front 47

Describe the calcofluor white + 10% KOH

Back 47

- UV fluorescence
- %10 chitin and cellulose binding for the fungal wall.
- sensitive

Front 48

Describe KOH and Parker Ink

Back 48

- no longer available
- was used most often for direct microscopy
- not as sensitive as calcofluor

Front 49

What does 10% KOh do?

Back 49

clears tissue and cell debris

Front 50

What does 10% glycerol do?

Back 50

- prevents crystallisation of reagent
- dyring out of specimen

Front 51

What is the differential characteristic of DTM?

Back 51

Dermatophytes produce ammonia which causes a pH change and goes from yellow to red.

Front 52

Explain the basic primary isolation conditions for fungi

Back 52

- Biosafety cabinets for subcutaneous and systemic fungi (I or II)
- microscopy is performed (Calcofluor + 10% KOH)
- 2 to 3 types of media is innoculated
- 30 C for 4 weeks
- Dimorphic 35 C for 8 weeks
- examined 3x weeks

Front 53

How long is the treatment for cryptococcus meningitis

Back 53

3 months

Front 54

How is Direct Microscopic Examination performed?

Back 54

**

Front 55

What is the primary isolation media specifically for Dermatophytes?

Back 55

Front 56

What does DTM contain?

Back 56

Front 57

Describe the Isolation of Fungi

Back 57

SICI
Safety: subcutaneous and systemic specimens must be processed in Biological safety cabinets

Innoculation: variety 2-3 types of media are innoculated.

Complimentary: complimentary factors in the media are combined to isolate the fungi

Incubation: sealed and incubated at 30 C for 4 weeks, dimorphic at 35C for 8 weeks.

Front 58

List types of PIM for fungi

Back 58

Media:

1. No antimicrobials - SDA
2. Antibiotics innoculated
- SABP: SDA + blood + polymixin B
- SABD: SDA + BHI + chloramphenicol + gentamicin
3. Antibiotic and Antifungals
- Mycose/MD: mycobiotic afar + chloramphenicol, gentamicin & cycloheximide.
4. CandidaCHROM

Front 59

What is observed in culture?

Back 59

1. Surface colour and reverse colour
2. Typography
3. texture
4. growth rate

Front 60

What temperature do pathogenic dermatophytes grow at?

Back 60

35C

Front 61

How is identification mainly derived?

Back 61

method of spore production

Front 62

Identification of Fungi depends on what main characteristics

Back 62

1. ability to visualise microscopic conidial features
2. Having a good slide preparation
3. Having a good microscope
4. Macroscopic appearance also assists in Id of fungi (IE: surface and reverse colour)

Front 63

How is Microscopy culture performed?

Back 63

cellotape preparation

Front 64

What is observed in microscopy culture?

Back 64

1. Microconidia shape,
2. Macroconidia shape, thickness of walls, sepate/non spetate
3. Observation of chlamydoconidia defn: thick walled thallic spores formed within the vegetative hyphae for survival.
4. Unique characteristics like spiral hyphae in Trichophyton mentagrophytes

Front 65

What is the following?

Back 65

pyriform microconidia

Front 66

What is the following?

Back 66

sub sperical microconidia

Front 67

What is the following?

Back 67

spherical microconidia

Front 68

Describe the following

Back 68

clavate microconidia

Front 69

Describe the above morphology

Back 69

ellipsoidal macroconidia

Front 70

Describe the above

Back 70

clavate of bullet shaped macroconidia

Front 71

Describe the above

Back 71

spindle shaped macroconidia

Front 72

Describe the above

Back 72

cigar shaped macroconidia

Front 73

Describe the above

Back 73

irregular shaped macroconidia

Front 74

How can macroconidia be described?

Back 74

1. wall thickness, wall texture
2. macroconidia shape

Front 75

How can microconidia be described?

Back 75

shape

Front 76

Identify the above

Back 76

characteristic smooth, thin-walled macroconidia, cigar shaped

Front 77

Identify the above

Back 77

chlamydoconidium

Front 78

Identify the above morphology

Back 78

thick walled spindle shaped macroconidia

Front 79

Identify the morphology of the above

Back 79

macroconidia are irregular, spindle-shaped, with rough thick walls
Microconidia are pyriform to clavate in shape

Front 80

Identify the morphology of the above

Back 80

ovoid to pyriform macroconidia with 1-3 cells,
relatively thin, finely rough walls, and broad truncate bases

Front 81

What are the four essential steps to the successful isolation of fungi?

Back 81

1. clinical suspicion of fungi by GP/ physician
2. Proper collection and transport
3. isolation through innoculation on to correct media and incubation conditions, followed by appropriate staining
4. informed and skilled microscopic examination

Front 82

Identify

Back 82

slender clavate to pyroform microconidia. barb wire like - Trichophyton rubrum

Front 83

Identify

Back 83

T. rubrum - white suede like to downy with a characteristic deep wine reverse pigment.

Front 84

Identify

Back 84

T. rubrum - scant to moderate number o

Front 85

What are the clinical symptoms, locations and terms for T. rubrum?

Back 85

CLINICAL SYMPTOMS:
- circular erythematous scaling border
- soft wrinkled skin
- brittle and discoloured nails
- Tinea pedis, Tinea cruris
- normally sees growth in 1 week

Front 86

What are the clinical symptoms, microscopic appearance and culture results for trichophyton mentagrophytes?

Back 86

clinical:
- scaly, erythematous lesion, scaly.
- kerion lesion of scalp with superlative foliculitis
- ectothrix infection - does not fluoresce

Front 87

Describe yeasts

Back 87

- unicellular
- blastoconidia reproduction
- mother cell develops to blastoconidia and separates.
- not inherently pathogenic - HME

Front 88

What are examples of yeasts that can become pathogenic?

Back 88

Candida
Cryptococcus
Malassezia
Rhodotorula
Trichosporon
Geotrichhum

Front 89

What are the two main pathogenic yeasts?

Back 89

Malassezia furfur

Front 90

What does pathogenic Malassezia furfur cause?

Back 90

pityriasis

Front 91

Describe the clinical presentation of Malassezia furfur

Back 91

- common
- mild
- recurrent
- pigmentation of redish, brown,white
- affect upper trunk, arms and upper body
- face legs and hands can be affected
- common in the tropics
- flaking of the skin/scaling
- most commonly seen in caucausions --> hyperpidmentation of the trunk
- depigmentation occurs in people of colour called pityriasis versicolor

Front 92

Describe the treatment for Malassezia furfur

Back 92

imidiazoles
shampoos

Front 93

Describe the culure of malassezia furfur

Back 93

- fluoresces under wood's lamp
- Dixon's media as it requires lipid base, or requires normal media + olive oil layer
- 37C incubation

Front 94

Describe the microscopic appearance of malassezia furufr in microscopy and culture

Back 94

MICROSCOPY
- thick round oval cells - clusters
- short angular hyphae forms
CULTURE
- small circular colonies pinkish

Front 95

Describe Dixon's agar

Back 95

Specialised isolation medium containing glycerol-mono-oleate. oily based media.

Front 96

What is the causative agent of white piedra

Back 96

trichosporon ovoides

Front 97

What is the clinical presentation of white piedra:?

Back 97

- light brown, green, red or white soft nodules around beard and moustache
- less firmly attached than black piedra

Front 98

What is the culture method for white piedra

Back 98

- SDA at room temperature
- white glabrous colonies within 5 days
- wrinkled

Front 99

What is the microscopic appearance of trichosporon ovoides? How is white piedra dx?

Back 99

- corn meal-tween 80
- hyaline hyphae
- blastoconidia
- arthoconidia
- biochemical tests

Front 100

What are the main diagnostic features of Trichosporon sp.?

Back 100

raised wrinkled colony
arthroconidia
basidiomycete class
urea positive
oval budding yeast celle

Front 101

What class is Trichosporon?

Back 101

Basidiomycete

Front 102

Identify

Back 102

Trichosporon spp.
- oval budding yeast cells

Front 103

Identify

Back 103

Front 104

What other characteristics would we look for here

Back 104

urease positive or negative?
culture that is raised and wrinkled colony
arthroconidia
oval budding yeast cells

Front 105

What is the causative agent of Tinea Nigra?

Back 105

Phaeo -annello- myces wernicki
phaeannellomyces wernicki

Front 106

What is the clinical presentation of tinea nigra?

Back 106

brown to black
non scaly
patches
hands

Front 107

What cultural media and procedure is used to isolate tinea nigra. What are we likely to see?

Back 107

SDA
room temp

Black yeasty colony - initial
slow growth
short olive grey mycelium turn to olive as aerial mycelia develop

Front 108

Describe the microscopic characteristics of phaeoannellomyces wernecki

Back 108

brown to dark
septate hyphae
2 celled yest cells
annelloconidia

Front 109

Describe the microscopic characteristics of phaeoannellomyces wernecki

Back 109