1. The document discusses four dimorphic fungi (Blastomyces dermatitidis, Coccidiodes immitis, Paracoccidiodes braziliensis, Histoplasma capsulatum) that cause systemic mycoses through inhalation of spores and subsequent yeast formation in tissues. 2. It also covers four opportunistic fungi (Candida albicans, Aspergillus species, Rhizopus/Mucor species, Cryptococcus neoformans) that can cause disease in immunocompromised individuals. 3. For each fungus, the document describes characteristics, diseases caused, pathogenesis, laboratory diagnosis, treatment and prevention.

1. Fungi Causing Systemic Mycoses
= majority causes inapparent infection
= causative organism are dimorphic fungi
1. Blastomyces dermatitides
Characteristics:
= dimorphic can exist as:
mold in soil, yeast in tissue
Yeast form is round-shaped with a thick
refractile wall and single broad-based bud
= natural habitat Is soil rich in organic material

2. Disease: Blastomycosis (Gilchrist’s Dse, North
American)
Blastomycosis
= a chronic infection characterized by formation of
suppurative and granulomatous lesion found
mainly in the lungs and disseminate
throughout the body
MOT = inhalation of airborne spore (conidia)
Pathogenesis: = infection occurs mainly in the
respiratory tract
= inhaled conidia differentiate into yeast
cell which initially cause abscesses
followed by formation of granuloma
= dissemination rare, but when it occurs
skin and bone are the most commonly
involved.

3. Laboratory Diagnosis:
1. Direct microscopic examination of sputum or skin
scrapping (KOH mount)/Tissue biopsy:
= demonstrate charac. thick walled “yeast cell with
single broad-based bud”
2. Culture - SDA
= grows as fluffy, brownish to white fungus which
produces pyriform spores
3. Hypersensitivity test – Blastomycin test
= Serological test not useful
Treatment: Itraconazole (drug of choice)
Amphotericin B - used to treat severe cases
Surgical excision helpful
Prevention: No vaccine or prophylactic drug available

4. 2. Coccidiodes immitis
Characteristics:
= dimorphic fungus that exist as:
spherules in tissues containing endospores
mold at 250
C in soil which forms hyphae with
alternating arthrospores
= natural habitat is soil
Disease: Coccidiodomycosis (San Joaquin Valley Fever,)
Dessert Fever
= disease simulate pneumonia wherein large part of the
lung becomes consolidated
MOT: inhalation of airborne arthrospores
Pathogenesis: Arthrospores inhaled →to the lungs →
forms spherules filled with endospore → rupture →
endospore release → forms new spherules → disseminate
throughout the body

5. Septate hyphae
Arthroconidia
Septate hyphae

6. Laboratory Diagnosis:
A) Microscopic examination of tissue scrapping or sputum
(KOH mount) = demonstrate the characteristic
spherules containing endospores
B) Culture
Sabouraud medium – presence of hyphae containing
arthrospores.
C) Serological test
Precipitin test– demonstrate a rising titer of IgM Ab
(indicates recent infection)
CF test - a rising titer IgG antibody indicates
dissemination of infection
D) Skin test – Coccidioidin test – using mycelial extract or
spherulin (an extract from spherules) as
antigen
= (+) test indicate prior infection but not necessarily
active disease
= useful in determining whether patient has been

7. Treatment: Ketoconazole (for primary infection)
Amphotericin B/Itraconazole (for disseminated infection)
Fluconazole - drug of choice in cases of meningitis
Prevention: No vaccine and Prophylactic drug available

8. 3. Paracoccidiodes braziliensis
Characteristics:
= dimorphic fungus exist as: mold in soil
yeast in tissue
(yeast form is thick walled with multiple buds)
resembling a ship steering-wheel
= habitat - soil
Disease: Paracoccidioidomycosis
(South American Blastomycosis)
= chronic granulomatous disease of the skin,mucous
membrane, lymph node and internal organs.
MOT : inhalation of airborne conidia
Pathogenesis: = spores are inhaled an early lesion
occurs
ion the lungs which disseminate to other organ
= asymptomatic infection common

9. Laboratory Diagnosis:
A) Direct microscopic examination from pus or
tissues (KOH mount)
= presence of large yeast cell w/multiple
buds
B) Culture
Sabourauds agar – presence of septate hyphae
with microconidia
C) Skin test not useful
D) Serological: CF/Immunodiffusion test - rise in AB
titer significant
Treatment: Itraconazole
Prevention: No vaccine available, Prophylactic drug
available

10. 4) Histoplasma capsulatum
= dimorphic fungus that exist as:
yeast cell in tissue w/c forms 2types of asexual spore
a) Tuberculate macroconidia
(thick-walled finger like projection)
b) Microconidia- thin, small, smooth-walled
mold in soil enriched with bird droppings
Disease: Histoplasmosis (Darling’s Disease)
= acute, benign pulmonary disease acquired by
inhalation of airborne spores (microconidia)
which are present from dropping of birds
= inhaled spore are engulfed by macrophages which
developed in to yeast form
= in tissue the organism occurs as oval body yeast
cell inside macrophages which spread
throughout the body especially liver and spleen

12. Laboratory Diagnosis:
A. Microscopic examination of sputum, tissue biopsy, bone
marrow aspirate
= oval yeast cell within macrophages
B. Culture
Sabourauds agar = presence of septate hyphae with
tuberculate chlamydospore in culture at 250
C is
diagnostic
BHIA – presence of fusiform blastospores with large
vacuole giving a characteristic cresent-shaped
appearance
C. Skin test – Histoplasmin test
-using mycelial extract as antigen
-useful for epidemiologic determination of incidence
of infection
-not use to diagnose actual disease
Treatment: Amphotericin B – for disseminated infection
Itraconazole - for pulmonary infection
Prevention: None (no vaccine available)

13. Budding yeast cell
inside macrophages

14. Fungi Causing Opportunistic Mycoses
= produce disease in those individual with impaired host
defenses
1. Candida albicans
Characteristics:
= is an oval yeast cell with a single bud
= part of the normal flora of the mucous membrane
of the upper respiratory tract, gastrointestinal
and female genital tract
= in tissues can appear as yeast cell or as
psuedohyphae (which are elongated yeast that
visually resembles hyphae but are not true hyphae)
= CHO fermentation reaction differentiate C-albicans
from other specie of Candida

15. MOT: - part of the normal of the skin, mucous membrane
and gastrointestinal tract of human
= no person to person transmission
Pathogenesis: Opportunistic pathogen
= disease may results when host defenses are
impaired
Diseases:
1. Thrush (Moniliasis)
2. Vulvovaginitis
3. Infection of the Nail (Paronychia)
4. Skin lesion occurs frequently in moisture-damage
skin
5. Systemic Candidiasis (disseminated form)

16. Laboratory Diagnosis:
A. Direct microscopic examination (KOH mount)
= presence of budding yeast cell w/pseudohyphae
B. Culture
SDA – presence of yeast cell, pseudohyphae
and large chlamydospore
Germ tube form in serum at 370
C differentiate
albicans from other species
C. Skin test with candida antigen
= (+) among immunocompetent adult and
are used as indicator that a person can mount
a cellular immune response

17. Treatment: Nystatin / Miconazole oral/topical
for skin and mucous membrane disease
Amphotericin B - disseminated infection
Ketoconazole – for chronic mucocutaneous
candidiasis
Prevention: No vaccine available
= predisposing factors should be reduced or
eliminated
= Clotrimazole trochis / Nystatin–used for
prevention of oral thrush

19. 2. Aspergillus fumigatus/Aspergillus flavus/Aspergillus
niger
Characteristics:
= exist only as mold with septate hyphae that branch
at a V-shaped angle
= monomorphic
= organism is normally found in soil
Diseases: 1. Aspergillosis (major disease)
= a granulomatous necrotizing disease of the lung
which often disseminates hematogenously to
various organs of the body
= involving the skin, eyes, ear, and other vital organ
= acquired by inhalation by airborne conidia
= can colonize and invade abraded skin and paranasal
sinuses causing fungal sinusitis
2. Allergic bronchopulmonary aspergillosis

21. Pathogenesis:
= opportunistic pathogen
= produce invasive disease among immunocompromised
individual
= organism can invade bloodvessels causing thrombosis
and infarction
= patient with lung cavity (tuberculosis) may develop
fungal ball (Aspergilloma)
= allergic patient with bronchial asthma can develop
allergic bronhopulmonary aspergillosis
Laboratory Diagnosis:
A. Microscopic examination (KOH mount) = presence of
hyaline septate hyphae, dichotomously branched
B. Culture – SDA – shows colonies with characteristic
radiating chain of conidia
C. Serological – detect IgG precipitin in patient with
aspergilloma and IgE antibody in patient with
bronchopulmonary aspergillosis

22. Treatment: Amphotericin B – for invasive aspergillosis
Surgical removal – for aspergilloma (fungus ball)
Steroid – recommended for allergic
bronchopulmonary aspergillosis
Prevention: No vaccine / Prophylactic drug available

23. 3. Rhizopus/Mucor
Characteristic:
= mold with non-septate hyphae w/ sporangiospore
that typically branch at 90O
angle
= monomorphic
= habitat in soil
MOT: inhalation of airborne spores
Disease: Mucormycoses (Zygomycoses;
Phycomycoses)
= is a systemic disease cause by saprophytic mold
(Mucor, Rhizopus and Absidia) found widely
in the environment
= acquired by inhalation of airborne asexual spore

24. Laboratory Diagnosis:
1. Microscopic examination of tissue (KOH mount)
= presence of non-septate hyphae that branch at
wide right angle
2. Culture – SDA - large hyaline coenocytic hyphae with
spores found inside sporangium
3. Serologic test – not available
Treatment: Amphotericin B
Prevention: No vaccine / Prophylaxis drug available

25. 4. Cryptococcus neoformans
= is an oval yeast-like budding cell surrounded by a
wide polysaccharide capsule
= not dimorphic
= habitat soil enriched with pigeon droppings
Disease: Cryptococcosis(Torulosis, European
Blastomycosis)
= most common life-threatening fungal disease in
AIDS patient
MOT: inhalation of airborne yeast cell
= no human to human transmission
Pathogenesis:
= lung infection as a result of inhalation is often
asymptomatic or may produce pneumonia
= disease occurs in patient with altered cell
mediated immunity especially AIDS patient
= spread via blood stream to the CNS and result to

26. Laboratory Diagnosis:
= Direct visualization of the encapsulated yeast-like
budding cell from spinal fluid by India Ink staining
(yeast cell surrounded by a wide unstained capsule)
= Culture (spinal fluid/sputum) SDA – presence of
encapsulated yeast cell.
= Serological – Latex particle agglutination test
- detects polysaccharide capsular antigen in
spinal fluid
Treatment: Amphotericin B plus Flucytosine for
meningitis
Prevention: No vaccine
= Cryptococcal meningitis can be prevented in AIDS
patient by oral Fluconazole

27. Capsule
Budding
yeast