INTRODUCTION TO FUNGAL INFECTIONS, Classification of Fungal Infections (mycoses), Pityriasis versicolor, Tinea nigra, Black piedra, White piedra 

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4. • Historically it was thought that fungi were plants that did not need
photosynthesis.
• But now fungi are classified in their own kingdom, separate from
plants and animals because:
1- The cell walls of plants are made of cellulose whereas the walls of fungal cells are
made of chitin
2- Plants require only simple inorganic compounds such as carbon dioxide and water
to grow. Fungi require a diet of complex organic molecules to thrive.
• Fungi are parasites or saprophytes i.e. they live off living or dead
organic matter.

5. • Growing fungi have branched filaments called
hyphae, which make up the mycelium (like branches
are part of a tree). Hyphae are threadlike filaments
made up of fungal cells, whereas mycelium is the
mass of hyphae that forms the fungal body. Some
fungi are compartmented by cross-walls (called
septae).
• Arthrospores are made up of fragments of the
hyphae, breaking off at the septae.
• Asexual spores (conidia) form on conidiophores. The
sexual reproductive phase of many fungi is unknown;
these are ‘fungi imperfecta’ and include those which
infect humans.

6. FORMS OF HYPHAE;
1. Septate hyphae: In most fungi, hyphae are divided
into cells by internal cross-walls for example
“Aspergillus”.
2. Coenocytic hyphae (non-septate hyphae): meaning
their hyphae are not partitioned by septa.
3. Pseudo hyphae: They are the result of incomplete
budding where the cells remain attached after
division, and Yeast can form pseudohyphae.

8. • Yeasts form a subtype of
fungus characterized by
clusters of round or oval cells.
• These bud out similar cells
from their surface to divide
and propagate. In some
circumstances they form a
chain of cells called a
pseudomycelium.

10. conidiophore

12. THE ORGANISMS ARE TRANSMITTED BY EITHER;
1. Direct contact with infected host (human or
animal).
2. Indirect contact with infected exfoliated skin or
hair in combs, hair brushes, clothing, furniture,
theatre seats, caps, bed linens, towels, hotel rugs,
and locker room floors.

13. • According to their appearance by microscopy and in
culture or method of reproduction.
BY THE METHOD OF REPRODUCTION:
1. Sexual
2. Asexual.

14. Classification of Fungal
Infections (mycoses)
I. SUPERFICIAL MYCOSES
a) Non-inflammatory
b) Inflammatory
II. SUBCUTANEOUS MYCOSES
III. SYSTEMIC MYCOSES

16. • These affect the outer layers of the skin, the nails and hair.
• The main groups of fungi causing
superficial fungal infections are:
1. Yeasts
i. Candida
ii. Malassezia
2. Dermatophytes (ringworm/tinea)
3. Other Moulds e.g.
i. Aspergillus spp.
ii. Fusarium spp.

17. Infections limited to the outermost layers of the skin
and hair:
1. Pityriasis versicolor
2. Candidiasis
3. Tinea nigra
4. Black piedra
5. White piedra

18. • Infections that extend deeper into the epidermis, as well as hair and nail
and caused by dermatophytes.
• They colonize the keratin and inflammation is caused by host response to
metabolic by-products:
1. Tinea capitis (head)
2. Tinea faciei (face)
3. Tinea barbae (beard)
4. Tinea corporis (body)
5. Tinea manus (hand)
6. Tinea cruris (groin)
7. Tinea pedis (foot)
8. Tinea unguium (nail)

19. THE MAIN 3 GENERA OF DERMATOPHYTES ARE:
1. Trichophyton (abbreviated as "T")
2. Epidermophyton (“E")
3. Microsporum (“M")

20. 1. Anthropophilic dermatophytes are restricted to human hosts and produce a mild, chronic
inflammation e.g.
 T. rubrum ▪ M. audouinii
 T. interdigitale ▪ T. violaceum
 T. tonsurans ▪ T. schoenleinii
2. Zoophilic organisms are found primarily in animals and cause marked inflammatory reactions in
humans who have contact with infected cats, dogs, cattle, horses, birds, or other animals e.g.
 M. canis (originating from dogs and cats)
 T. equinum (originating from horses)
 T. verrucosum (originating from cattle)
3. Geophilic species are usually recovered from the soil but occasionally infect humans and animals.
They cause a marked inflammatory reaction, which limits the spread of the infection and may lead
to a spontaneous cure but may also leave scars e.g.
 M. gypseum
 M. fulvum

22. • These involve the deeper layers of the skin (the dermis,
subcutaneous tissue, muscle & fascia and even bone).
• The causative organisms normally live in the soil living on
rotting vegetation. They can get pricked into the skin as a
result of an injury but usually stay localized at the site of
implantation.
• Deeper skin infections include:
1. Mycetoma
2. Chromoblastomycosis
3. Sporotrichosis

24. • May result from breathing in the spores of fungi, which
normally live in the soil or rotting vegetation or as
opportunistic disease in immune compromised
individuals.
A. Inhaled fungal infection (By True pathogens)
• Although uncommon, some may infect healthy
individuals. The result is most often a mild infection and
long lasting resistance to further attack, but occasionally
these infections are more serious and chronic (especially
in the immune suppressed). The organisms causing
systemic fungal infections include:
1. Histoplasmosis
2. Coccidioidomycosis (North and South America).
B. Opportunistic infections
• Other systemic mycoses only infect those who are already
sick or with an immunodeficiency disorder i.e. they are
‘opportunists’. Repeated infection may occur. Risks for
systemic mycoses include:
1. Serious illness and debility
2. Cancer or leukemia
3. Diabetes mellitus
4. Transplant
5. Massive doses of antibiotics
6. Parenteral nutrition
7. Drug addiction
8. Infection with human immunodeficiency virus (HIV)
• Opportunistic fungal infections include:
1. Aspergillosis (found everywhere)
2. Zygomycosis
3. Cryptococcosis (where there are pigeon droppings)
4. Trichosporon beigelii
5. Pseudallescheria boydii

27. • It is a common, long-term (chronic) superficial
fungal infection of the skin.
• Affected skin change color and become either
lighter or darker than surrounding skin.

28. • Common in adolescent and young adult males.
Malassezia requires oil to grow, accounting for the
increased incidence in adolescents and preference for
sebum-rich areas of the skin.
• Its occurrence before puberty or after age 65 years is
uncommon.
• A member of normal human cutaneous flora, and it is
found in 18% of infants and 90-100% of adults and it is
NOT CONTAGIOUS.

29. • Worldwide distribution but prevalence reported to
be as high as 50% in the humid, hot environment
and as low as 1.1% in the colder temperatures.
• The condition is more noticeable during the
summer months.

30. • The causative fungus is Malassezia furfur (previously known as
Pityrosporon orbiculare and Pityrosporon ovale).
• In patients with clinical disease, the organism is found in both the
yeast stage and the filamentous (mycelial/hyphae) form.
• Factors that lead to the conversion to the parasitic, mycelial
morphologic form include;
1. Genetic predisposition
2. Oily skin (yeast is lipophilic)
3. Excessive sweating
4. Warm, humid environments
5. Immuno-suppression
6. Malnutrition
7. Pregnancy
8. Cushing disease

31. • The reason why this organism causes PVC in some
individuals while remains as normal flora in others is not
entirely known.
• Several factors, such as the organism's nutritional
requirements and the host's immune response to the
organism, are significant.
• Lymphocyte function on stimulation with the organism
has been shown to be impaired in patients who are
affected.

32. • Decreased pigmentation may be secondary
to the inhibitory effects of dicarboxylic acids
on melanocytes (these acids result from
metabolism of surface lipids by the yeast).
• Sun exposure may make PVC more
apparent. Decreased tanning, due to the
ability of the fungus to filter sunlight.
• The yeasts induce enlarged melanosomes
within melanocytes in the brown type of
PVC.

33. • Pityriasis versicolor is usually
asymptomatic, but in some people it
is mildly itchy.
• Numerous, well-marginated, finely
scaly, oval-to-round macules.
• Demonstration of this associated
scale may require scratching or
stretching the skin surface.

34. • Scattered over the trunk,
shoulders and/or the chest,
the proximal extremities
with occasional extension
to the lower part of the
abdomen and the neck.
• Less frequently, lesions are
seen on the face (especially
in children), scalp.

38. • The macules tend to coalesce, forming large irregularly shaped patches.

39. • As the name versicolor implies, the color of each lesion varies
from almost , pink (mildly inflamed), tan to dark brown

43. • An INVERSE form also exists affecting the flexural regions
antecubital fossae, sub-mammary region and groin.

45. • Sometimes the patches start scaly and brown, and
then resolve through a non-scaly and white stage.

46. • Usually diagnosed clinically.
• Wood’s light examination
(revealing bright yellow-green
fluorescence).

47. • SKIN SCRAPING: then it is examined under a
microscope.
• DIRECT MICROSCOPY: Skin scrapings taken from
patients with PVC stain rapidly when mounted in 10%
KOH, glycerol and Parker ink solution and show
characteristic clusters of thick-walled round, budding
yeast-like cells and short angular hyphal forms up to
8um in diameter (SPAGHETTI AND MEATBALLS
APPEARANCE). These microscopic features are
diagnostic for Malassezia furfur and culture
preparations are usually not necessary.

49. • CULTURE: is only necessary in cases of
suspected fungaemia. M. furfur is a
lipophilic yeast, therefore in vitro growth
must be stimulated by natural oils or other
fatty substances.
• The most common method used is to
overlay Sabouraud's dextrose agar
containing cycloheximide (actidione) with
olive oil or alternatively to use a more
specialized media like Dixon's agar which
contains glycerol mono-oleate (a suitable
substrate for growth).

50. • Biopsies are usually not
performed, as KOH examination
of associated scale is typically
diagnostic.
• This section shoes;
1. Hyperkeratosis without
parakeratosis
2. Few inflammatory cells in the
epidermis
3. Numerous yeast & plump hyphae
(Spaghetti and meatballs)

53. 1. Pityriasis alba
2. Postinflammatory hypopigmentation
3. Vitiligo
4. Seborrheic dermatitis
5. Pityriasis rosea
6. Tinea corporis
7. Secondary syphilis
8. Progressive macular hypomelanosis

54. TOPICAL TREATMENT
1. Azole creams and lotions; Clotrimazole,
Ketoconazole, Miconazole
2. Dandruff shampoos Ketoconazole (1% or 2%) or
2.5% selenium sulfide twice weekly for 2 to 4
weeks; the preparation is left on the skin for 10–15
minutes before rinsing. Over-the-counter dandruff
shampoo contain heavy metals e.g. Zinc, Mercury,
Copper e.t.c.  inhibition of growth of any fungi by
reacting in their biosynthetic pathways. Treatment
of all the skin from the neck down to the knees,
even if only a small area is clinically involved.
3. Allylamine
4. Nystatin
5. Salicylic acid
6. Sodium thiosulphate solution
7. Ciclopirox cream/solution
8. 50% propylene glycol in water

55. SYSTEMIC TREATMENT
• If the rash is extensive, oral antifungal medications may be needed they are;
1. Fluconazole (300 mg once weekly for 2 weeks)
2. Itraconazole (200 mg daily for 5-7 days)
3. Ketoconazole (200 mg 5 days-5 weeks),
• Vigorous exercise an hour after taking the medication may help sweat it onto
the skin surface, where it can effectively eradicate the fungus. Avoid bathing
for a few hours.

56. • Though it is easily treated, pigment changes may last for months
after treatment.
• Because this rash has a high recurrence rate, medication may be
needed periodically to prevent recurrence. The rate of recurrence
of pityriasis versicolor is very high, especially in hot humid climates
so avoid heat in hot weather.
• Patients at high risk for recurrence may be helped by using
ketoconazole shampoo once weekly as a body cleanser. Another
preventative measure is once-monthly dosing of oral ketoconazole
(400 mg), fluconazole (300 mg) or itraconazole (400 mg).

59. • It is due to infection by the fungus,
Hortaea werneckii.
• Occurs as a result of inoculation
from a contamination source such
as soil sewage, wood, or compost
subsequent to trauma in the
affected area.
Note the 2 celled yeast forms

60. • Typically occur in tropical climates such as Central and
South America, Africa, Asia and, occasionally, in the
southeastern US.

61. • No predispositions have been identified.
• Typically, the incubation period is 10- to 15-day.
• A pigmentary change in the skin results from the
accumulation of a melanin-like substance in the
fungus.

62. • Asymptomatic brown-to-black sharply
marginated macule or patch, resembling
silver nitrate or India ink stains.
• The surface may appear mottled, velvety or
have mild scale.
• The lesions are typically solitary, although
may be multiple.
• Although most frequently seen on the
palms, tinea nigra can also appear on the
soles, neck and trunk.

65. • The shape of the lesion varies, and they may appear
ovoid, round, or irregular.
• The lesion slowly grows over weeks to months.
• The size may range from a few millimeters to
several centimeters in diameter, depending on the
duration.
• It may have darker pigmentation of the advancing
border as compared to the center.
• While the disease tends to be chronic, recurrence
after effective treatment is infrequent except in the
case of re-exposure.

67. • KOH EXAMINATION reveals highly
branched and septate pigmented
hyphae.
• BIOPSY specimens have similar findings
observed within the stratum corneum.
• CULTURES of H. werneckiifirst appear
as pasty, green-black colonies with a
yeast-like appearance, and then change
after approximately 2 weeks to a fuzzy,
dematiaceous (dark in color) mold.

69. 1. Acral melanocytic nevi.
2. Fixed drug eruption.
3. Postinflammatory hyperpigmentation.
4. Staining from chemicals, pigments and dyes.
5. Melanoma.

70. 1. Topical keratolytic agents such as Whitfield’s ointment
(typically 6% benzoic acid plus 3% salicylic acid)
2. Topical azole
3. Topical Allylamine
• Several weeks of therapy may be required to prevent
recurrence of disease.
• Systemic therapy is generally not indicated.

73. • It is a superficial non-inflammatory nodular fungal
infection confined to hair shafts.
• “Piedra” means “stone”, reflecting the fungal
elements’ adherence to one another to form
nodules along the hair shaft, the surrounding skin is
healthy.
• Favored climate; tropical areas.
• There are 2 types Black Piedra & White Piedra.

81. BLACK PIEDRA WHITE PIEDRA
CAUSATIVE FUNGI Piedraia hortae
Trichosporon beigelii (6
pathogens)
PATHOGENESIS
• Infection usually begins
under the cuticle of the
hair shaft and extends
outward.
• Hair breakage may occur
as a result of shaft rupture
at the site of the nodules.
• As the nodules enlarge,
they can even envelope
the hair shaft.
• Infection also begins
beneath the cuticle and
grows through the hair
shaft, causing weakening
and breakage of the hair.

82. CLINICALLY BLACK PIEDRA WHITE PIEDRA
NODULE COLOR
Brown to black
along the hair shaft.
Generally white but may also be red, green or
light brown in color.
NODULE FIRMNESS Hard Soft
NODULE ADHERENCE TO
THE HAIR SHAFT Firm Loose
TYPICAL ANATOMIC
LOCATION
Face, axillae and
pubic region
(occasionally scalp)
Scalp and face (occasionally pubic region its
incidence has increased since the start of the
HIV pandemic)
SYSTEMIC INFECTION Non
In immunosuppressed patients, T. beigelii can
cause TRICHOSPORONOSIS, a serious with
fungemia, fever, pulmonary infiltrates, skin
lesions (papulovesicular and purpuric, often
with central necrosis) and renal disease.

83. INVESTIGATIONS BLACK PIEDRA WHITE PIEDRA
KOH EXAMINATION
“crush preparation”
• Dematiaceous hyphae
• Organized cluster of asci, each of
which contains eight ascospores
(sexual phase of P. hortae-the only
sexual phase detected that is
pathological to human)
• Non-dematiaceous
hyphae
• Blastoconidia and
arthroconidia
(representing the
asexual state)
CULTURE ON
SABOURAUD’S AGAR
• Very slow-growing
• Dark green to dark brown–black
colonies with a velvety texture
(asexual phase)
• Grows rapidly
• Moist, cream-colored,
yeast-like colonies
• Cycloheximide inhibits
growth.

85. 1. Pediculosis (nits)
2. Hair casts
3. Trichorrhexis nodosa
4. Trichomycosis axillaris
5. Scaly scalp conditions

86. 1. Clip affected hairs.
2. Wash affected hairs with antifungal shampoo 2%
ketoconazole shampoo or selenium sulfide.
3. Topical imidazole cream.
4. Oral terbinafine may also be used for black piedra.
5. Oral itraconazole may also be used for white
piedra.