Deep mycoses. Fungal infection

1. INTRODUCTION
• Mycoses refers to infection by fungal agents.
• Fungi are eukaryotes with cell wall that grow
as multi cellular filaments (molds) OR
individual cells alone or in chains (yeast).
• Molds consist of thread like filaments called
Hyphae.

2. INTRODUCTION
Hyphae produce round cells , called Conidia, that easily become
airborne, disseminating the fungus.

3. INTRODUCTION
• Many pathogenic fungi are dimorphic, forming
hyphae at ambient temperatures but yeasts at
body temperature (e.g.Blastomyces, Histoplasma
etc.).
• Mycoses are of Four major types –
1. Superficial and coetaneous mycoses.
2. Subcutaneous mycoses.
3. Endemic mycoses.
4. Opportunistic mycoses.

4. INTRODUCTION
• Deep mycosis includes – subcutaneous
mycoses, endemic mycosis (caused by
Dimorphic fungi) and Life threatening systemic
illness in Opportunistic mycoses ,seen in
Immuno compromised or prosthetized
individuals.

5. METHODS OF SPECIMEN
COLLECTION FOR DIAGNOSING
MYCOSES
• The diagnosis of mycotic infection is contingent
upon the proper selection, collection and
transport of the appropriate clinical sample.
• Specimen volume must be adequate to perform
all the tests. In case of inadequate sample at least
two swabs to be taken for microscopy and
culture.
• If material is inadequate , it can be collected with
sterile swab stick moistened with NS.

6. CONTD…
• Skin scraping and hair should be transported in
dry container or envelop.
• It is essential for specimens to be collected
aseptically from the deeper part of the wound or
else superficial contaminating fungi or bacteria
will overgrow and suppress pathogenic fungi.
• Rapid transport of specimens in less than two
hours ensures optimum recovery of fungi.

7. CONTD…
• Scanty material/ dry swab ,not acceptable.
• The ‘saline for injection’ solution which may
contain anti microbial substance should be
avoided while collecting biopsy tissue for HPE
or grains from sinus tract.
• Tissue specimen to be sent in saline and not in
formal saline , for culture.

8. TRANSPORT OF SPECIMENS
• Specimen must be transported and processed
within two hours of collection preferably.
• To minimize the overgrowth of commensals (In
case of specimen taken from nose, oral mucosa,
nail etc.) Penicillin (20U/ml), Streptomycin
(1,00,000 mcg/ ml) or Chloramphenicol (0.2gm/
ml) may be added to the specimen.
• In case of delay specimen can be stored under
refrigeration at 4 degree C. but not more than 24
hours.

9. CONTD…
• Blood and CSF are stored at 30 - 37 degree C .
Dermatological specimens at 15- 30 degree C.
• Specimen like subungual debris, hair, skin
scraping can be directly inoculated on to the
appropriate media immediately after
collection for the optimum recovery of the
fungi.

10. SUBCUTANEOUS MYCOSES
• MYCETOMA - etiologic agent may be bacterial
or fungi. Discussion here will be
restricted to fungal mycetoma or eumycetoma.
• CHROMOBLASTOMYCOSIS
• PHAEOHYPHOMYCOSIS
• SPOROTRICHOSIS
• LOBOMYCOSIS
• RHINOSPORIDIOSIS

11. MYCETOMA
• Mycetoma - clincal syndrome of localized,
indolent, deforming, swollen lesions and sinuses,
involving cutaneous and subcutaneous tissues,
fascia, and bone; usually occurring on the foot or
hand) - etiologic agent may be bacteria or fungi.
• Mycotic mycetoma - usually more common in
men (3:1 to 5:1) than in women.
• Usually results from trauma or puncture wounds
to feet, legs, arms and hands (usually on the
feet).

12. MYCETOMA
• Starts out as tumor-like to subcutaneous
swelling.
•
• Ruptures near the surface; infects deeper
tissues including subcutaneous tissues and
ligaments (tendons, muscles and bone are
usually spared).
• Small particles or grains leak out of the lesions
- these represent the yellowish microcolonies.

13. MYCETOMA
• Lesions of mycetoma seldom heal spontaneously.
• Disease is chronic may continue for 40-50 years.
• Ketoconazole appears to be ineffective in clinical trials.
• Intravenous miconazole (9 mg per Kg of body weight
sometimes higher doses) shows promise.
• Surgery and removal of tumor ( if small it is encapsulate, if
larger amputation my be required).
• Combining miconazole and surgery may prove useful in
effectively treating the disease.

14. MYCETOMA

15. MYCETOMA

16. MYCETOMA
Eumycotic mycetoma granules,pink coloured in
PAS stain

17. CHROMOBLASTOMYCOSIS
• Disease is one of hyperplasia, characterized by the
formation of verrucoid (rough), warty, cutaneous
nodules, which may be raised 1-3 cm above the skin
surface. The roughened, irregular, pedunculated
vegetations often resembles the florets of
cauliflower.
• This disease is caused by Fonsecaea pedrosoi and
Phialophora verrucosa (identical to Cadophora
americana which causes bluing of lumber), both of
which are dematiaceous fungi (darkly pigmented).
• occurs rarely in animals (such as, horses, cats, dogs,
and frogs).
• soil-inhabiting fungi

18. CHROMOBLASTOMYCOSIS
• Susceptibility enhanced by going barefoot or wearing
sandals.
• Found almost exclusively in laborers.
• Enters hand or feet after trauma.
• Found primarily in the tropics or subtropics.
• Dull red or violet color on skin may resemble a
ringworm lesion.
• Develops into a verrucous lesion.
• Pruritus (itchiness) and papules may develop.

19. CHROMOBLASTOMYCOSIS
• Fungus gets under the skin (produces bumps).
• Bumps may block lymphatic system and cause
elephantiasis.
• Sometimes bacterial infection may enter and
cause a secondary infection.
• Rarely this fungus spreads to other areas of the
subcutaneous tissue.
• Potentially may spread to brain (life-threatening
in that case)

20. CHROMOBLASTOMYCOSIS
• Identification
– Biopsy tissue - look at the skin for fungus.
– Hematoxylin stain - look for fungal cells scattered among
skin cells.
– Attempt to culture fungus from biopsy tissue must always
take place to identify the etiological or causal agent .
– Colonies of fungi are dark or blackish.
– Two species implicated in this mycosis - each may produce
several spore types
• Fonsecaea pedrosoi - Cladosporium type and
Rhinocladiella type of conidiation
• Phialalophora verrucosa - Phialophora type (flowers in
the vase conidiation)
– Fungi found growing on plant debris, wood, soil.

21. CHROMOBLASTOMYCOSIS
• Treatment
– usually not fatal or necessarily painful
– unsightly disease
– no really good cure
– thiabendazole - shows promise (given orally and on skin
mixed with dimethyl sulfoxide [DMSO] - to deliver drug) -
experimental drug
– surgical excision, electrodesiccation, or cryosurgery are
useful in early stages of disease
– application of heat to infect site has been reported to
effect a cure of the disease after six months of treatment
(using pocket warmers)
– itraconazole shows promise in clinical trials.

22. CHROMOBLASTOMYCOSIS

23. CHROMOBLASTOMYCOSIS (Fonsecaea
spp.)

24. CHROMOBLASTOMYCOSIS (Phialophora
spp.)

25. PHAEOHYPHOMYCOSIS
• Subcutaneous or brain abscess caused by
dematiaceous fungi.
• Affected site: thigh , legs, feet, arms ..etc, brain
(cerebral)
• Lesion: neuro and abcesses
• Etiology:
(a) Dematiaceous imperfect mold fungi, mainly:
Cladosporium, Exophiala, Wangiella, Cladophialphora
bantiana (C. bantianum) , Ramichloridum mackinziei,
Bipolaris, Drechslera, Rhinocladiella, C. Cladosporoides,
E. jeanselmei, W. dermatitidis’

26. PHAEOHYPHOMYCOSIS
(b)Neutrophic fungi : cerebral PHM as R.
mackinziei, C. bantianum.
• Naturally in woody plant, woods, agricultural soil
• Laboratory diagnosis:
Specimens: pus, biopsy tissue.
• Direct microscopic examination: KOH and smear
brown septate hyphae
• Culture on SDA and, it’s very slow growing black
or grey colonies.

27. PHAEOHYPHOMYCOSIS

28. PHAEOHYPHOMYCOSIS

29. SPOROTRICHOSIS
• Lesions: Lymphocutaenouse and subcutaenous
granulomatous lesion-suppurate, ulcerate.
• The lesion are nodules or ulcers in local lymphatics
• Affected sites: extremities, joints.
• In agriculture communities
• Etiology
Dimorphic imperfect fungus in trees, sharps, decaying
vegitations.
• Sporothrix schenckii. Yeast in human tissues and at 37C
in culture.

30. SPOROTRICHOSIS
• Mold in culture and room temperatures with floweret's of
conidia.
• Laboratory diagnosis:
specimen:
• Biopsy tissue, ulcerative material
• Direct microscopy: smear ---finger –like yeast cells or cigar
shaped some are oval.
• Culture:
On SDA at room temperature to grow mold , and on blood A at
37c to grow yeast.
• Treatment: septrin, KI.

31. SPOROTRICHOSIS

32. SPOROTRICHOSIS

33. LOBOMYCOSIS
• Cutaneous-subcutaneous fungal infection
• Lesion: keloidal-verrucoid-nodular
• Site: face, ear, arms, legs
• Chronic-localized
• Etiology:
Lacazia loboi=Loboa loboi
• Obligately parasitic fungus
• Does not grow in culture like SDA media or tissue
culture

34. LOBOMYCOSIS
• Laboratory diagnosis: the specimen is biopsy
tissue-direct microscopy will show chains of
cells
• Culture of specimen will be negative
• Management: surgical excision of lesion

35. LOBOMYCOSIS

36. RHINOSPORIDIOSIS
• Clinical: Mucocutaenous fungal infection
• Sites: nasal, oral, (palate, epiglottis),
conjunctiva
• Lesion: polyps, papilomas, warts-like lesion
• More seen in communities near swamps
• Etiology:
Rhinosporidium seebri

37. RHINOSPORIDIOSIS
• Obligatory parasitic fungus
• Believed to be chytridiomycetes (div. mastigo),
doesn't grow on artificial media but has been
grown in tissue culture
• Laboratory diagnosis: specimens, biopsy tissue
• Direct microscopy: stained section or smears
KOH, will show spherules with endospores
• Culture on SDA will be negative
• Management: cryosurgical excision of lesion-
relapse common

38. RHINOSPORIDIOSIS

39. RHINOSPORIDIOSIS

40. ENDEMIC MYCOSIS
1) COCCIDIOIDOMYCOSIS.
2) BLASTOMYCOSIS.
3) PARACOCCIDIOIDOMYCOSIS.
4) HISTOPLASMOSIS.

41. COCCIDIOIDOMYCOSIS
• Disease
Coccidioides immitis
causes
coccidioidomycosis.
• Properties
C. immitis is a dimorphic
fungus that exists as a
mold in soil and as a
spherule in tissue.

42. Transmission & Epidemiology
Coccidioide
• The fungus is endemic in arid regions of the
southwestern United States and Latin America.
• People who live in Central and Southern
California, Arizona, New Mexico, Western Texas,
and Northern Mexico, a geographic region called
the Lower Sonoran Life Zone, are often infected.
• In soil, it forms hyphae with alternating
arthrospores
and empty cells.
• Arthrospores are very light and are carried by the
wind.
• They can be inhaled and infect the lungs.

43. Pathogenesis of Coccidioide
• In the lungs, arthrospores form spherules that are large,
have a thick, doubly refractive wall, and are filled with
endospores.
• Upon rupture of the wall, endospores are released
and differentiate to form new spherules.
• The organism can spread within a person by direct
extension or via the bloodstream.
• Granulomatous lesions can occur in virtually any organ but
are found primarily in bones and the central nervous
system (meningitis).
• Dissemination from the lungs to other organs occurs in
people who have a defect in cell-mediated immunity.

44. Pathogenesis of Coccidioide
• Most people who are infected by C. immitis
develop a cell-mediated (delayedhypersensitivity)
immune response that restricts the growth of the
organism.
• One way to determine whether a person has
produced adequate cell-mediated immunity to
the organism is to do a skin test (see below).
• In general, a person who has a positive skin test
reaction has developed sufficient immunity to
prevent disseminated disease from occurring.
• If, at a later time, a person's cellular immunity is
suppressed by drugs or disease, disseminated
disease can occur.

45. Clinical Findings of Coccidioide
• Infection of the lungs is often asymptomatic and is evident
only by a positive skin test and the presence of antibodies.
• Some infected persons have an influenza like illness with fever
and cough.
• About. 50% have changes in the lungs (infiltrates, adenopathy,
or effusions) as seen on chest x-ray.
• 10% develop erythema nodosum (see below) or arthralgias.
• This syndrome is called "valley fever" or "desert
rheumatism"; it tends to subside spontaneously.
• Disseminated disease can occur in almost any organ; the
meninges, bone, and skin are important sites.

46. Clinical Findings of Coccidioide
• The overall incidence of dissemination in persons
infected with C. immitis is 1%, although the
incidence in Filipinos and African Americans is 10
times higher.
• Women in the third trimester of pregnancy also
have a markedly increased incidence of
dissemination.
• Erythema nodosum (EN) manifests as red, tender
nodules ("desert bumps") on extensor surfaces
such as the shins.
• It is a delayed (cell-mediated) hypersensitivity
response to fungal antigens and thus is an
indicator of a good prognosis.

47. Clinical Findings of Coccidioide
• There are no organisms in these lesions; they are not a
sign of disseminated disease. EN is not specific for
coccidioidomycosis; it occurs in other granulomatous
diseases, eg, histoplasmosis, tuberculosis, and leprosy.
• In infected persons, skin tests with fungal extracts cause
at least a 5mm induration 48 hours after injection
(delayed hypersensitivity reaction).
• Skin tests become positive within 2-4 weeks of infection
and remain so for years but are often negative in patients
with disseminated disease.

48. Laboratory Diagnosis of
Coccidioide• In tissue specimens, spherules are seen microscopically.
• Cultures on Sabouraud's agar incubated at 25 °C show
hyphae with arthrospores
• (Caution: Cultures are highly infectious; precautions
against inhaling arthrospores must be taken.)
• In serologic tests, IgM and IgG precipitins appear
within 2-4 weeks of infection and then decline in
subsequent months.
• Complement-fixing antibodies occur at low titer
initially, but the titer rises greatly if dissemination
occurs

49. COCCIDIOIDES IMMITIS SHOWING TYPICAL
SINGLE-CELLED, HYALINE, RECTANGULAR TO
BARREL-SHAPED, ALTERNATE
ARTHROCONIDIA

50. TREATMENT & PREVENTION OF
COCCIDIOIDE
• No treatment is needed in asymptomatic or mild primary
infection.
• Amphotericin B (Fungizone) or itraconazole is used for
persisting lung lesions or disseminated disease.
• Ketoconazole is also effective in lung disease.
• Fluconazole is the drug of choice for meningitis.
• Intrathecal amphotericin B may be required and may
induce remission, but long-term results are often poor.
• There are no means of prevention
except avoiding travel to endemic areas.

51. Tissue section showing typical endosporulating spherules of
C. immitis
COCCIDIOIDOMYCOSIS

52. BLASTOMYCOSIS
• Blastomyces dermatitidis causes
blastomycosis, known as North American
blastomycosis.

53. PROPERTIES OF
BLASTOMYCES• B. dermariridis is a dimorphic fungus that exists as a
mold in soil and as a yeast in tissue.
• The yeast is round with a doubly refractive wall and a
single broad-based bud
• Note that this organism forms a broad-based bud,
whereas Cryptococcus neoformans is a yeast that
forms a narrow-based bud.

54. TRANSMISSION & EPIDEMIOLOGY
OF BLASTOMYCES
• This fungus is endemic primarily in eastern North
America, especially in the region bordering the Ohio,
Mississippi, and St. Lawrence rivers, and the Great Lakes
region.
• Less commonly, blastomycosis has also occurred in
Central and South America, Africa, and the Middle East.
It grows in moist soil rich in organic material, forming
hyphae with small pear-shaped conidia.
• Inhalation of the conidia causes human infection.

55. PATHOGENESIS & CLINICAL
FINDINGS OF BLASTOMYCES
• Infection occurs mainly via the respiratory
tract.
• Asymptomatic or mild cases are rarely
recognized.
• Dissemination may result in ulcerated
granulomas of skin, bone, or other sites.

56. LABORATORY DIAGNOSIS OF
BLASTOMYCES
• In tissue biopsy specimens, thick-walled yeast cells
with single broad-based buds are seen microscopically.
• Hyphae with small pear-shaped conidia are visible on
culture.
• The skin test lacks specificity and has little value.
• Serologic tests have little value.

57. Tissue sections showing
large, broad-base, unipolar
budding yeast-like cells
BLASTOMYCOSIS

58. TREATMENT & PREVENTION OF
BLASTOMYCES
• Itraconazole is the drug of choice for most
patients.
• Amphotericin B should be used to treat severe
disease.
• Surgical excision may be helpful.
• There are no means of prevention.

59. PARACOCCIDIOIDOMYCOSIS
• Paracoccidioides brasiliensis causes
paracoccidioidomycosis, also known as
South American blastomycosis.

60. PROPERTIES OF
PARACOCCIDIOIDES
• P. brasiliensis is a dimorphic fungus that exists as a
mold in soil and as a yeast in tissue.
• The yeast is thick walled with multiple buds, in
contrast to B. derrnatitidis, which has a single bud .

61. TRANSMISSION & EPIDEMIOLOGY
OF PARACOCCIDIOIDES
• The spores are inhaled, and early lesions occur
in the lungs.
• Asymptomatic infection is common.
• Alternatively oral mucous membrane lesions,
lymph node enlargement, and sometimes
dissemination to many organs develop.

62. LABORATORY DIAGNOSIS OF
PARACOCCIDIOIDES
• In pus or tissues, yeast cells with multiple buds are seen
microscopically.
• A specimen cultured for 2-4 weeks may grow typical
organisms.
• Skin tests are rarely helpful.
• Serologic testing shows that when significant antibody
titers (by immunodiffusion or complement fixation) are
found, active disease is present.

63. TREATMENT & PREVENTION OF
PARACOCCIDIOIDES
• The drug of choice is itraconazole taken orally
for several months.
• There are no means of prevention.

64. MULTIPLE, NARROW BASE, BUDDING YEAST
CELLS
"STEERING WHEELS" OF P. BRASILIENSIS

65. PARACOCCIDIOIDOES
BRASILIENSIS
Multiple, narrow base, budding
yeast cells "steering wheels" of
P. brasiliensis

66. HISTOPLASMOSIS
• Histoplasma capsulatum causes histoplasmosis.
• H. capsulatum is a dimorphic fungus that exists as a
mold in soil and as a yeast in tissue.
• It forms two types of asexual spores
(1) Tuberculate macroconidia, with typical thick walls
and fingerlike projections that are important in
laboratory identification,
(2) Microconidia, which are smaller, thin, smoothwalled
spores that, if inhaled, transmit the infection.

67. TRANSMISSION & EPIDEMIOLOGY
OF HISTOPLASMA
• This fungus occurs in many parts of the world.
• In the United States it is endemic in central and eastern
states, especially in the Ohio and Mississippi River
valleys.
• It grows in soil, particularly if the soil is heavily
contaminated with bird droppings, especially from
starlings.
• Although the birds are not infected, bats can be infected
and can excrete the organism in their feces.

68. TRANSMISSION & EPIDEMIOLOGY
OF HISTOPLASMA
• In areas of endemic infection, excavation of the soil
during construction or exploration of bat-infested
caves has resulted in a significant number of infected
individuals.
• In several tropical African countries, histoplasmosis is
caused by Histoplasrna duboisii.
• The clinical picture is different from that
caused by H. capsulatum.
• A description of the differences between African
histoplasmosis and that seen in the United States is
beyond the scope of this book.

69. PATHOGENESIS & CLINICAL
FINDINGS OF HISTOPLASMA
• Inhaled spores are engulfed by macrophages and
develop into yeast forms.
• In tissues, H. capsulatum occurs as an oval budding
yeast inside macrophages

70. PATHOGENESIS & CLINICAL
FINDINGS OF HISTOPLASMA
• The yeasts survive within the phagolysosome of the
macrophage by producing alkaline substances, such
as bicarbonate and ammonia, that raise the pH and
thereby inactivate the degradative enzymes of the
phagolysosome .
• The organisms spread widely throughout the body;
especially to the liver and spleen, but most infections
remain asymptomaric, and the small grantdomatous
foci heal by calcification.

71. PATHOGENESIS & CLINICAL
FINDINGS OF HISTOPLASMA
• With intense exposure (eg, in a chicken house or
batinfested cave), pneumonia may become clinically
manifest.
• Severe disseminated histoplasmosis develops in a small
minority of infected persons, especially infants and
individuals with reduced cell-mediated immunity, such as
AIDS patients.
• In AIDS patients, ulcerated lesions on the tongue are typica]
of disseminated histoplasmosis. In immunocompetent
people, EN can occur (see description of EN in Coccidioides
above).

72. PATHOGENESIS & CLINICAL
FINDINGS OF HISTOPLASMA
• EN is a sign that cell-mediated immunity is active and
the organism will probably be contained.
• A skin test using histoplasmin (a mycelial extract)
becomes positive, ie, shows at least 5 mm of
induration, within 2-3 weeks after infection and
remains positive for many years.
• However, because there are many false-positive
reactions (due to cross-reactivity) and many false-
negative reactions (in disseminated disease), the skin
test is not useful for diagnosis.

73. PATHOGENESIS & CLINICAL
FINDINGS OF HISTOPLASMA
• Furthermore, the skin test can stimulate an antibody
response and confuse the serologic tests.
• The skin test is useful for epidemiologic studies, and
up to 90% of individuals have positive results in areas
of endemic infection.

74. LABORATORY DIAGNOSIS OF
HISTOPLASMA
• In tissue biopsy specimens or bone marrow
aspirates, oval yeast cells within macrophages are
seen microscopically.
• Cultures on Sabouraud's agar show hyphae with
tuberculate macroconidia when grown at low
temperature, eg, 25°C and yeasts when grown at
37°C.
• Tests that detect Histoplasma antigens by
radioimmunoassay and Histoplasma RNA with DNA
probes are also useful.

75. LABORATORY DIAGNOSIS OF
HISTOPLASMA
• An antibody titer of 1:32 in the CF test with yeast
phase antigens is considered to be diagnostic.
• However, cross-reactions with other fungi, especially
Blastomyces, occur.
• CF titers fall when the disease becomes inactive and
rise in disseminated disease.
• The ID test detects precipitating antibodies
(precipitins) by forming two bands, M and H, in an
agar-gel diffusion assay.
• The ID test is more specific but less sensitive than the
CF test.

76. PAS stain showing Histoplasma
capsulatum yeast cells in liver specimen

77. Rough-walled macroconidia
Macroconidia and microconidia
HISTOPLASMA CAPSULATU

78. INTRACELLULAR YEAST OF
HISTOPLASMA

79. TREATMENT & PREVENTION OF
HISTOPLASMA
• No therapy is needed in asymptomatic or mild primary
infections.
• With progressive lung lesions, oral itraconazole is
beneficial.
• In disseminated disease, arnphotericin B is the treatment
of choice.
• In meningitis, fluconazole is often used because it
penetrates the spinal fluid well.

80. TREATMENT & PREVENTION OF
HISTOPLASMA
• Oral itraconazole is used to treat pulmonary or
disseminated disease, as well as for chronic
suppression in patients with AIDS.
• There are no means of prevention except avoiding
exposure in areas of endemic infection.

81. SUMMARY
Agent infection Dissemination Drug of choice
Blastomyces
dermatitidis
Blastomycosis Skin and bone
Later nervous system and visceral
organs
Amphotericin B
itraconazole
Coccidioides immitis Coccidioidomycosis Skin, bones, joints, subcutaneous
tissues, and visceral organs
Amphotericin B
Paracoccidioidoes
brasiliensis
Paracoccidioidomycosis Oro-nasal mucosa
latter spleen, liver, intestine and
skin
Amphotericin B +
sulfas or azoles
Histoplasma
capsulatum
Histoplasmosis Acute pneumonia (cave disease)
Chronic pneumonia (smoker)
Disseminated
(immunocompromised)
Primary cutaneous
(lab accidents)
Amphotericin B

82. OPPORTUNISTIC MYCOSES
• Opportunistic mycoses are fungal infections that do not
normally cause disease in healthy people.
• Do cause disease in people with weakened immune
defenses (immunocompromised people).
• Weakened immune function may occur due to
inherited immunodeficiency diseases, drugs that
suppress the immune system (cancer chemotherapy,
corticosteroids, drugs to prevent organ transplant
rejection), radiation therapy, infections (e.g., HIV),
cancer, diabetes, advanced age and malnutrition.

83. CLASSIFICATION OF
OPPORTUNISTIC MYCOSE
1) Candidiasis.
2) Aspergillosis.
3) Cryptococcosis.
4) Mucormycosis.

84. CANDIDIASIS
C. albicans is a member of the indigenous microbial
flora of humans.
• Found in the gastrointestinal tract, upper
respiratory tract, buccal cavity, and vaginal tract.
• Growth is normally suppressed by other
microorganisms found in these areas.
• Alterations of gastrointestinal flora by broad
spectrum antibiotics or mucosal injury can lead
to gastrointestinal tract invasion.

85. CANDIDIASIS
• Skin and mucus membranes are normally an
effective barrier but damage by introduction of
catheters or intravascular devices can permit
Candida to enter the bloodstream.
• In healthy individuals candida causes Vaginitis
and Diaper rash.
• Severe disseminated candidiasis most commonly
occurs in neutropenic patients due to leukemia,
chemotherapy etc. and leads to DIC or shock.

86. PATHOGENESIS OF
CANDIDIASIS
• A single strain of candida can be successful as
commensal & pathogen.
• Candida shift between different phenotypes
called “ phenotypic switching “.
• Phenotypic switching involves co-ordinated
regulation of phase specific genes.
• These variants exhibit altered colony morphology,
cell shape, Antigenicity & virulence.

87. PATHOGENESIS OF
CANDIDIASIS
• Candida produce large number of functionally
distinct Adhesins that contribute virulence.
• Adhesins include-
1. Integrin like protein that binds to fibronectin,
laminin.
2. A protein that binds to epithelial cells
3. Several agglutinins that bind to endothelial cells
/ fibronectin.

88. PATHOGENESIS OF
CANDIDIASIS
• Candida produce enzymes like-
1. Asprtyl proteinases- Tissue invasion by
degrading extracellular matrix.
2. Catalases- Resist oxidative killing by phagocytic
cells.
• C. albicans grow as biofilms ( microbial
communities 0f yeast +filamentous form ),
specially on prosthetic materials.

89. PATHOGENESIS OF
CANDIDIASIS
• Neutrophis, macropgages & T H 17 cells are important
for protection against candida infection.
• Neutrophil & macrophages phagocytose candida and
oxidative killing by phagocytic first line Host defence.
• Increased risk of canida infection in Neutropenic
patients or patients with NADPH Oxidase /
Myeloperoxidase defficiency.
• Filamentous form can escape from phagocytic damage.

90. PATHOGENESIS OF
CANDIDIASIS
Yeast cell β 1-3 glucan
Dectin on dendritic cells
Induce production of IL-6, IL-23
TH 17 response
Recruitment of neutrophil & monocytes.

91. CLINICAL FINDINGS OF
CANIDIDIASIS

92. OPPORTUNISTIC INFECTION BY
CANDIDA ALBICANS IN AN AIDS PATIENT

93. LAB DIAGNOSIS OF CANDIDA
• In tissue section C. albicans appearas as yeast,
PSEUDOHYPHAE.
• Pseudohyphae are chain of budding yeast cells
joined end to end at constrictions.
• All forms may be present togather and seen in H
& E stain.
• Special fungal stain like Gomori Methamine Silver,
PAS can better visualize them.

94. MORPHOGENESIS
Figure 2. Morphogenic forms of
Candida albicans
Figure 1. Morphogenesis.
Morphogenesis in
C. albicans is a pivotal
virulence factor that allows
rapid multiplication and
subsequent dissemination
in host tissue.

95. FIGURE 1. SKIN EQUIVALENT BEFORE INFEC
FIGURE 2. INFECTION WITH
PATHOGENIC CLINICAL ISOLATE OF C.
ALBICANS.
AFTER 48 H THE YEAST PENETRATES
THE SKIN EQUIVALENT AND DESTROYS
THE TISSUE
FIGURE 3. INFECTION WITH NON-
PATHOGENIC C. ALBICANS. THIS STRAIN IS
NOT ABLE TO PENETRATE INTO THE
TISSUE AND THUS BEHAVES AS AVIRULENT
AS SHOWN IN THE MOUSE MODEL OF
VIRULENCE ASSAY OF DIFFERENT C. ALBICANS STRAINS USING THE
SKIN EQUIVALENT

96. ASPERGILLOSIS
• Aspergillus fumigatus most common
pathogenic species causes diseases in
human.
• Portal of entry – Inhalation of conidia.
• Major Risk factors
1. Neutropenia.
2. Use of corticosteroids.

97. PATHOGENESIS OF
ASPERGILLOIS
• Alveolar macrphages recognize aspergillus
through TLR-2 & Lectin Dectin- 1 ( which
recognizes β 1, 3 glucan of conidia ).
• Activation of phagocytes to ingest & kill
conidia.
• In immunosuppressed patients conidia can
germinate into hyphae, which invades tissue.

98. PATHOGENESIS OF
ASPERGILLOIS
• TLR recognizes products of hyphae & release
pro inflammatory Cytokines like IL-β , TNF- α
& Chemokines
• Neutrophils come into action
• Oxidative damage of hyphae
• Invasive aspergillosis highly associated with
Neutropenia & impaired neutrophil defenses.

99. PATHOGENESIS OF
ASPERGILLOIS
• Virulence Factors :
1. Adhesins.
2. Antioxidants( Melanin, Catalase, SOD ).
3. Toxins ( Aflatoxin -> Ca Liver ).

100. CLINICAL FINDINGS OF
ASPERGILLOSIS
1. Sinusitis, Aspergillus asthma.
2. Colonizing Aspergillosis( Aspergilloma )- growth of
fungus in pre existing pulmonary cavity -> Fungal ball
-> recurrent haemoptysis.
3. Invasive Aspergillosis-
Immunosuppressed host, widespread hematogenous
spread involves heart valves, brain.
Pulmonary invasive aspergillosis show necrotizing
pneumonia (Target lesion ).

101. LAB DIGNOSIS OF ASPERGILLOSIS
• Form fruiting bodies & hyaline septate hyphae
, branching at acute angle (40 degree ).

103. CRYPTOCOCCOSIS
• Human disease- C. neoformans
C. gattii.
• Risk Factors :
1. AIDS
2. Leukemia.
3. Lymphoma.
4. Immunosuppressed transplant individuals.
• Presnt in soil & bird droppings and Mode of transmission
is Inhalation.
• C. gattii causes infection in otherwise normal individual.

104. PATHOGENESIS OF
CRYPTOCOCCOSIS
• Virulence Factors :
1. Polysaccharide capsule- prevent phagocytosis (Phenotypic
switching ).
2. Melanin
• Anti oxidant property.
• Cell wall integrity.
• Counteract effects of antifungal agents.
• Decreased phagocytosis.
3. Enzymes – Phenol Oxidase , cleaves fibronectin & other
basement membrane protein ,aids tissue invasion.

105. CLINICAL FINNDINGS OF
CRYPTOCOCCOSIS
• Involves meninges, cortical grey matter and
basal nuclei.
• In immunocompromised individuals
gelatinous masses of fungi grow in meninges.
• Skin involvement is second common.
• Bone incolvement may also occur.

106. LAB DIAGNOSIS OF
CRYPTOCOCCOSIS
• In CSF :Capsule negatively stained in indian ink
preparation.
• In tissue specimen : 5 – 10 micrometer
cryptococcal yeast characterised by intense
red polysccharide capsule in mucicarmine &
PAS stain.

107. MUCORMYCOSIS
• Mucormycotina are widely distributed in nature.
• No harm to immunocompetent individulas.
• They infect immunosuppressed people, causing
mucormycosis.
• Causative agents
1. Mucor
2. Rhizopus
3. Cunninghamella.
• Mode of transmission : Inhalation

108. PATHOGENESIS OF
MUCORMYCOSIS
• Inhaled spore causes infection in the sinuses &
lungs.
• Macrophages provide initial defence by
phagocytosis & nonoxidative killing of
sporangiospores.
• Hyphal component of mucormycotina recognized
by TLR- 2  release of proinflammatory
cytokines (IL-6 , TNF – α ) & Chemokines
neutrophils  damage to hyphal wall.

109. PATHOGENESIS OF
MUCORMYCOSIS
• Iron promotes growth of mucormycotina.
• Increased possibility of infection seen in
diabetics due to increased free Iron (
ketoacidosis, glycosylation induced poor
affinity for iron )

110. CLINICAL FINDINGS OF
MUCORMYCOSIS
• Rhino cerebral mucormycosis : Local tissue
necrosis , invade arterial walls & penetrates
the periorbital tissue & cranial vault 
Meningoencephalitis with or without cerebral
infarction.
• Lung involvement : Hemorrhagic pneumonia.

111. LAB DIAGNOSIS OF
MUCORMYCOSIS
• In Tissue specimen : Non septate hyphae with
branching at right angle (distinct from
aspergillus ) readily demonstrated in H & E
stained section.
• Culture : In SDA @ 37 degree C. Dense Hairy
Colony.