A summarised details of fungal organism of clinical importance . Dermatophytes and systemic mycosis

1. OYEKAN SEUN
Mycology has become important clinically
because of increasing cases of
immunocompromised patients
1
MYCOLOGY
study of fungi (molds, yeasts, and mushrooms).

2. Fungi
2
 Eukaryotic cells (e.g., true nucleus, 8OS ribosomes,
mitochondria
 Lack chlorophyll therefore Heterotrophic (require
organic carbon)
 Saprophytic or saprobic (fungus living on dead organic material)
 Parasitic (fungus living on another living organism)
 Require an aerobic environment.
 Complex carbohydrate cell walls
 chitin, glucan, and mannan.
 potent antigens to the human immune system
 Bilayered cell membrane: innermost layer around the
fungal cytoplasm.
 It contains sterols called ergosterol
 Amphotericin B and nystatin bind to ergosterol and punch holes in the
fungal cell membrane,
 Ketoconazole inhibits ergosterol synthesis.
 Capsule: Polysaccharide coating that surrounds the
cell wall.
 Antiphagocytic virulence factor in by Cryptococcus neoformans.

3. TERMS
3
 Yeast: Unicellular growth form of fungi, spherical to
ellipsoidal.
 Yeast reproduce by budding.
 When buds do not separate, they can form long chains of
yeast cells called pseudohyphae.
 Yeast reproduce at a slower rate than bacteria.
 Hyphae: Threadlike, branching, cylindrical, tubules
composed of fungal cells attached end to end.
 These grow by extending in length from the tips of the
tubules.
 Molds (also called Mycelia): Multicellular colonies
composed of clumps of intertwined branching hyphae.
 Molds grow by longitudinal extension and produce spores.
 Spores: The reproducing bodies of molds, rarely seen in
skin scrapings.
 Dimorphic fungi: Fungi that can grow as either a yeast
or mold, depending on environmental conditions and
temperature (usually growing as a yeast at body
temperatures.

4. Morphology
4
 Nonseptate Hyphae
 No cross walls
 Broad hyphae with irregular width
 Broad angle of branching
 Septate Hyphae
 With cross walls
 Width is fairly regular (tube-like) .
 DIMORPHIC FUNGI
 Blastomyces
 Histoplasma
 Coccidioides
 Paracoccidioides
 Sporothrix
 Body Heat Changes Shape
 Pseudohyphae (Candida albicans)
 Hyphae with constrictions at each septum

5. Spore types
5
 Conidia
 Asexual spores, Formed off of hyphae
 Common and is usually Airborne
 Blastoconidia:
 "Buds" on yeasts (asexual budding daughter yeast cells)
 Arthroconidia:
 Asexual spores formed by a "joint"
 Spherules and Endospores ( Coccidioides):
 Spores inside the spherules in tissues

6. Classification of Fungi
Medically important fungi are in four phyla:
Zygomycota
Ascomycota
Basidiomycota
Deuteromycota
6

7. Zygomycota:
 Have aseptate hyphae
 Asexual reproduction by spores contained in a
sporangium -
 Sexual reproduction by production of Gametes
(zygospores)
 e.g Mucor, Rhizopus, Absidia
7

8. Ascomycota:
 Sac fungi
 Have septate hyphae
 Asexual reproduction is by formation of
conidia
 Sexual reproduction occurs in a sac called
an ascus resulting in the formation of
ascospores.
 E.g. Trichophyton, Microsporum, Blastomyces,
Histoplasma
8

9. Basidiomycota
 Club fungi.
 Septate hyphae
 Asexual reproduction by formation of conidia
 Sexual reproduction occurs by extrusion from a
club-like structure called a basidium.
 E.g Cryptococcus (Filobasidiella)
9

10. Deuteromycota
 Fungi Imperfecti
 Have septate hyphae
 A-sexual reproduction by production of conidia
 Sexual phase has not yet been identified.
 E.g. Trichosporon, Torulopsis, Candida,
Pityosporum, Epidermophyton, Coccidiodes,
Paracoccidiodes
10

11. 11
Culture
•May take several weeks
• Sabouraud agar
• Blood agar
Both of the above with
antibiotics to inhibit
different organism

12. ANTI FUNGI TREATMENTS
12
1. Antifungal agents that are used for serious systemic
infections:
 Amphotericin B, the grandfather of antifungal agents. This drug
covers almost all medically important fungi but must be given
intravenously (not absorbed orally) and causes many side
effects. It may also be given intrathecally (into the cerebrospinal
fluid).
 Itraconazole, given orally, has now proven useful for many of
these infections.
2. Antifungal agents that are used inless serious
systemic infections
 Oral azole drugs. The prototype is ketoconazole, others are
fluconazole and itraconazole ( mentioned above).
3. Antifungal agents that are used for superficial
fungal infections:
 Griseofulvin (taken orally) and the many topical antifungal

13. 13

14. 14

15. NONSYSTEMIC FUNGAL
INFECTIONS
Superficial
Cutaneous
Subcutaneous
15

16. Superficial Infections
16

17. Superficial Infections
(Keratinized Tissues)
17
 Pityriasis vesicolor or tinea versicolor
 Caused by Malassezia furfur (Normal skin flora
(lipophilic yeast))
 Chronic superficial fungal infection which leads to
hypopigmented or hyperpigmented patches on the
skin.
 Moist, warm climates predispose
 With sunlight exposure, the skin around the patches
will tan, but the patches will remain white.
 Tinea nigra
 This infection is caused by Exophiala werneckii
 causes dark brown to black painless patches on the
soles of the hands and feet.

18. Diagnosis
18
 Diagnosis of both infections is based on
microscopic examination of skin scrapings, mixed
on a slide with potassium hydroxide (KOH).
 This will reveal hyphae and spherical yeast, as the
KOH digests nonfungal debris.
 Malassezia looks like spaghetti (hyphae) with
meatballs (spherical yeast).
 Coppery-orange fluoresence under Wood lamp
(UV)

19. Treatment
19
 Treatment of both consists of spreading
dandruff shampoo containing SELENIUM
SULFIDE over the skin.
 This is an inexpensive and effective treatment
 The topical antifungal imidazoles can also be
used.

20. 20

21. •Dermatophytoses
•Yeast candiditis /Cutaneous
candiditis
21
CUTANEOUS FUNGAL INFECTIONS
of
the SKIN, HAIR, and NAILS

22. Dermatophytoses
22
 Group of Filamentous fungi (monomorphic)
 They live in the dead, horny layer of the skin, hair, and
nails(keratinophilic)
 Since keratin is the primary structural protein of skin, nails, and hair
 They secrete an enzyme called keratinase, which digests
keratin(keratinolytic).
 The digestion of keratin manifests as scaling of the skin,
loss of hair, and crumbling of the nails.
 They are the most most common fungal infection of
man
 They do not disseminate into systemic infection
 More than 30 species of fungi.
Three genera:
 Trichophyton- Infects skin, hair and nails
 Microsporum- Infects skin and hair

23. ECOLOGY OF DERMATOPHYTES
23
1. Anthropophilic: Associated with humans only.
Person -to-person transmission through
contaminated objects (comb, hat, etc.)
2. Zoophilic: Associated with animals. Direct
transmission to humans by close contact with
animals.
3. Geophilic: Usually found in soil. Transmitted to
humans by direct exposure.
 Severity of ringworm disease depends on
 strains or species of fungus involved and
 sensitivity of the host to a particular pathogenic fungus.
 More severe reactions occur when a dermatophyte
crosses non-host lines (e.g., from an animal species
to man).

24. Dermatophytic Infections = Tineas
(Ringworms)
24
 Following invasion of the horny layer of the skin, the
fungi spread, forming a ring shape with a red, raised
border. This expanding raised red border represents
areas of active inflammation with a healing center. This
is appropriately called ringworm, since it looks like a
ring-shaped worm under the skin
 Itching is the most common symptom of all
tineas.
 If highly inflammatory, generally contacted from
animals (zoophilic) (i.e., Microsporum canis:
cats or dogs)
 If little inflammation, generally contacted from
humans (anthropophilic tinea capitis: M.

25. 25
 Tinea capitis = ringworm of the scalp
 `The most serious of the tineas capitiis FAVUS ( TINEA FAVOSA),
which causes permanent hair loss and is very contagious.
 Ectothrix infections often resolve on their own.
 Endothrix infections my become chronic and may continue into
adulthood.
 Tinea barbae = ringworm of the bearded region
 Tinea manuum - ringworm infection of the hand
 Tinea corporis (body)= ringworm of the glabrous skin
 Tinea cruris (jock itch)
 red patches on the groin and scrotum(penis not usually
affected)
 More common in men than women.
 Tinea pedis (athlete's foot)
 Commonly begins between the toes, and causes cracking
and peeling of the skin.
 T. rubrum, T. mentagrophytes, and Epidermophyton
floccosum are causes of Tinea pedis
 Tinea unguium (onychomycosis) = ringworm of the
nails
 nails are thickened, discolored, and brittle

26. Diagnosis
26
 Dissolve skin or nail scrapings in potassium
hydroxide(KOH).
 The KOH digests the keratin.
 Microscopic examination should show arthroconidia
and hyphae.
 Direct examination of hair and skin with Wood's light
or lamp (ultraviolet light at a wavelength of 365nm).
Microsporum fluoresces a bright yellow-green
 Using a Wood's lamp, on hair Microsporum
species tend to fluoresce green while
Trichophyton species generally do not fluoresce

27. Treatment
27
 Keep affected area dry and exposed to the drying
effects of the air
 Topical imidazoles. or tolnaftate
 Oral griseofulvin is used with tinea capitis and tinea
unguium and when hairs are infected, or skin contact
hurts
 Griseofulvin becomes incorporated into the newly
synthesized keratin layers, inhibiting the growth of
fungi.
 So the skin fungi is cleared only after the old keratin
has been replaced.

28. Candida albicans
28
 The last type of cutaneous fungal infection is caused
by Candida albicans.
 Candida can infect the mouth (oral thrush), groin (diaper
rash), and the vagina (Candida vaginitis).
 It can also cause opportunistic systemic infections.

29. Subcutaneous fungal infections gain entrance to the
body following trauma to the skin. They usually remain
localized to the subcutaneous tissue or spread along
lymphatics to local nodes. These fungi are normal soil
inhabitants and are of low virulence.
29
Subcutaneous Mycoses

30. Sporothrix schenckii
30
 Sporothrix schenckii is a dimorphic fungi commonly
found in soil and on plants (rose thorns and splinters).
 Causes; Sporotrichosis (rose gardener disease)
 An occupational hazard for gardeners.
 Following a prick by a thorn contaminated with Sporothrix
schenckii, a subcutaneous nodule gradually appears This
nodule becomes necrotic and ulcerates. The ulcer heals,
but new nodules pop up nearby and along the lymphatic
tracts up the arm.
 Pulmonary (acute or chronic) sporotrichosis occurs in
Urban alcoholics, particularly homeless (alcoholic rose-
garden-sleeper disease).it can also disseminate to joints
&bones (osteoarticular sporotrichosis) or
CNS(sporotricosis meningitis) though all RARE

31. Diagnosis and treatment
31
 Microscopic examination of this fungus reveals yeast
cells that reproduce by budding. Culture at 37°C
reveals yeast, while culture at 25°C reveals branching
hyphae(dimorphism)
 Environmental form on plant material appears as
hyphae with rosettes and sleeves of conidia.
 Tissue form appears as cigar-shaped yeast in tissue
 Treat with oral potassium iodide in milk or
amphotericin B/itraconazole

32. Phialophora and Cladosporium
(Chromoblastomycosis/chromomycosis)
32
 Chromoblastomycosis is a subcutaneous infection
caused by a variety of copper colored soil
saprophytes (Phialophora, Fonsecaea and
Cladosporium) found on rotting wood.
 Infection occurs following a puncture wound.
 Initially, a small, violet wartlike lesion develops.
 Over months to years, additional violet-colored wartlike
lesions arise nearby.
 Clusters of these lesions resemble cauliflower.
 Skin scrapings with KOH reveal copper-colored
sclerotic bodies. Treat with itraconazole and
local excision.

33. SYSTEMIC FUNGAL INFECTIONS
33

34. SYSTEMIC FUNGAL INFECTIONS
34
 Four fungi that are dimorphic and causes systemic
disease in humans are
 Histoplasma capsulatum,
 Blastomyces dermatitides,
 Coccidioides immitis also paracoccidiodes brasilensis
 They are dimorphic fungi and also cause the same type
of diseases
 They grow as mycelial forms, with spores, at 25°C on
Sabouraud's agar. At 37°C on blood agar, they grow in
a yeast form
 Present as mycelium in the environment releasing spores
that are inhaled by humans and become yeast In the
human host
 Others are oppourtunistic
 Cryptococcus neoformans
 Candida albicans
 Aspergillus flavus and fumigatus
 Pneumocystis jirovecii formerly P. carinii

35. The 3 fungi have 3 clinical
presentations
35
1. Acute pulmonary infection : The majority of cases are
asymptomatic or mild respiratory illnesses that go
unreported. Usually in the immunocompetent.
2. Pneumonia: with fever, cough, and chest X-ray infiltrates.
Like tuberculosis can show granulomas with calcifications
can follow resolution of the pneumonia. A chronic cavitary
pneumonia can also occur, marked by weight loss, night
sweats, and low-grade fevers, much like a chronic
tuberculosis pneumonia.
3. Disseminated infection; such as meningitis, bone lytic
granulomas, skin granulomas that break down into ulcers,
and other organ lesions.
This disseminated form commonly occurs in the
immunocompromised host.

36. Pathogenesis
36
 Like Mycobacterium tuberculosis the 3 fungi are
acquired by inhalation. However, unlike
Mycobacterium tuberculosis, the fungal infections are
inhaled as a spore form and are never transmitted
from person to person. Rather, the spores are
aerosolized from soil, bird droppings, or vegetation.
 Like Mycobacterium tuberculosis, once inhaled, local
infection in the lung is followed by bloodstream
dissemination.
 In most infected persons the fungi are destroyed at
this point by the cell-mediated immune system.
 Antigenic preparations called coccidioidin and
histoplasmin are like the PPD of Mycobacterium
tuberculosis showing induration after 24-48hours of

37. Diagnosis
37
 Biopsy of the affected tissue
 The tissue can be examined with silver stain for
yeast or can be grown on Sabouraud's agar or blood
agar.
 Serologic tests can be helpful (complement fixation,
latex agglutination).

38. Treatment
38
 Acute pulmonary histoplasmosis and
coccidioidomycosis usually require no treatment, as
the infection is mild.
 For chronic or disseminated disease, itraconazole or
amphotericin B is often required for months!
 All Blastomyces infections require aggressive
amphotericin B or itraconazole treatment.

39. Histoplasma capsulatum
39
 Nonencapsulated despite its name.
 Endemic region are States following drainages of Great
Lakes to Gulf of Mexico)
 Eastern Great Lakes, Ohio, Mississippi, and Missouri River
beds
 Found in soil (dust) enriched with bird or bat feces
 Affects Spelunking (cave exploring), cleaning chicken
coops, or bulldozing starling roosts
 Facultative intracellular parasite found in reticuloendothelial
(RES) cells
 tiny; can get 30 or so in a human cell
African histoplasmosis (H.duboisii) (H. capsulatum var.
duboisii) affects the bones and skin rarely the lungs in
contrast H.capsulatum that affects majorly the lungs

40. Disease :fungus flu
40
 Normal patient with acute pulmonary;
 Hepatosplenomegaly may be present even in acute
pulmonary infections (facultative intracellular RES)
 Immunocompromised patient with chronic pulmonary or
disseminated infection
 Diagnosis: Sputum or blood cultures with mononuclear
cells packed with yeast cells
 Treatment: Itraconazole for mild, amphotericin B for
severe
Differentiation of african from classical histoplasmosis
 Larger,thick-walledyeast cells
 Pronouncedgiant cellformation in infectedtissue
 Diminishedpulmonaryinvolvement
 Greater frequencyof skinand bone lesions

41. Coccidioides immitis
41
 Endemic region: Southwestern United States
 Southern california, Arizona, New Mexico, Texas,
Nevada
 Environmental form: hyphae breaking up into
arthroconidia found in desert sand
 Arthroconidia are inhaled, round up, and enlarged,
becoming spherules inside which the cytoplasm
walls off, forming endospores.
 Tissue form: spherules with endospores
 C. immitis is the leading cause of laboratory-acquired
fungal infection since it Is more virulent than its other
counterpart

42. Disease: Valley fever
42
 Asymptomatic to self-resolving pneumonia
 Normal patient with erythema nodosum or self-
resolving pneumonia
 Desert bumps (erythema nodosum) and arthritis
are generally good prognostic signs.
 Systemic infections are a problem in AIDS and
immunocompromised patients in endemic region
 Tendency to disseminate in third trimester of
pregnancy
 Sputum has spherules with endospores
 Treatment: Azoles for mild to moderate (itraconazole,
etc.), amphotericin B for severe

43. Blastomyces dermatitidis
43
 The rarest systemic fungal infection
 Mainly in North America
 Fungi are isolated from soil and rotten wood.
 Environmental form: hyphae with nondescript conidia
 Tissue form: broad-based budding yeasts and a
double refractile cell wall

44. Disease: Blastomycosis
44
 Considered less likely to self-resolve than
Histoplasma or Coccidioides, so many physicians
will treat even acute infections.
 Disseminated disease in immunocompromised
 Sputum has broad-based, budding yeasts with
double, refractile cell walls
 Treatment: Itraconazole for mild, amphotericin B for
severe

45. Opportunistic Fungi
45
 Cryptococcus neoformans
 Candida albicans
 Aspergillus flavus and fumigatus
 Pneumocystis jirovecii formerly P. carinii
 Mucor, Rhizopus, Absidia (Zygomycophyta)

46. Cryptococcus neoformans
46
 Polysaccharide Encapsulated Yeast
 Worldwide distribution
 Environmental Source: Soil enriched with pigeon
droppings. Therefore affects pigeon breeders
 Causes Cryptococcosis, a type of
meningoencephalitis
 Following inhalation and local lung infection, often
asymptomatic, the yeast spreads via the blood to the brain
 Cause of meningitis in Hodgkins/ AIDS patient
 Almost 10% of AIDS patients develop cryptococcosis
 A subacute to chronic meningitis develops in
cryptococcosis with headache, nausea, confusion,
staggering gait, and/or cranial nerve deficits.
 Fever and meningismus can be mild
 Cryptococcus can also cause pneumonia, skin ulcers,
and bone lesions like the other systemic fungi.

47. Diagnosis
47
 CSF examination with An India ink stain shows
yeast cells with a surrounding halo, the
polysaccharide capsule. This test is positive half of
the time(misses in 50%)
 So used to rule in and not rule out the infection
 A more sensitive test is the cryptococcal antigen
test, which detects cryptococcal polysaccharide
capsular antigens.
 by latex particle agglutination or counter immunoelectrophoresis
 Culture will confirm the diagnosis. A urease
positive yeast
 The usual treatment is with amphotericin B and
flucytosine(5FC).
 Persons require treatment for as long as 6 months with serial lumbar
punctures to confirm resolution.
 AIDS patients may require treatment for life.

48. Candida albicans
(and other species of Candida)
48
 Takes up different forms
 Yeast endogenous to our mucous membrane normal flora(skin and UG
tract)
 C. albicans yeasts form germ tubes at 37°C in serum(Germ tube
test)
 Other species include C. glabrata, C. krusei, C. parapsilosis , C.
tropicalis, C. keyfri
 Forms pseudohyphae and true hyphae when it invades tissues
(nonpathogenic Candida do not).
 Germ tube test is a diagnostic test in which a sample of fungal spores
are suspended in animal serum and examined by a microscope

49. Diseases and predispositions
49
 Perleche/Angular chelitis : crevices/fissure of mouth maybe
due to malnutrition
 Oral thrush: Patches of creamy white exudate with a reddish
base cover the mucous membranes of the mouth.
 These are difficult to scrape off with a tongue blade.
 Swish and spit preparations of nystatin or amphotericinB, or
 merely sucking on imidazole candy will resolve this infection.
 Vaginitis: Women develop Candida vaginitis more frequently
when taking antibiotics, oral contraceptives, or during menses
and pregnancy. (increased estrogen levels) Corticosteroids,
intrauterine devices, and diaphragm use
 The symptoms are vaginal itching and thick copious discharge
 Speculum examination reveals inflamed vaginal mucosa and patches of
cottage cheese-appearing white clumps affixed to the vaginal wall.
 Usually a problem of diabetic women
 Imidazole vaginal suppositories are helpful.
 Diaper rash: Warm moist areas under diapers and in adults
between skin folds (eg under breasts) can become red and
macerated secondary to Candida invasion.

50. Diseases and predispositions
50
 Esophagitis: Extension of thrush into the esophagus
causes burning substernal pain worse with
swallowing.
 Candida does not infect the esophagus in immune-competent
persons
 Endoscopy: Can extend to the stomach causing gastritis
 Confirmatory biopsy shows the presence of yeasts and
pseudohyphae invading mucosal cells, and culture reveals
Candida.
 Disseminated: Candida can invade the blood stream
and virtually every organ.
 Pustular skin lesions, Muscle abscess,
 The retina must be examined with the ophthalmoscope.
Multiple white fluffy candidal patches occasionally may be
visualized.
 Since Candida is a normal flora, it is often cultured from the
urine, sputum, and stool. These can represent contaminants.
However, isolation from the blood is never normal
 Endocarditis after transient septicemias seen in IV drug

51. Diagnosis and treatment
51
 Candida can also be Gram stained
 Diagnosis is made with KOH preparation of skin
scrapings, or with stains and cultures of biopsied
tissue or blood in septicemia
 pseudohyphae, true hyphae, budding yeasts
 For Topical infections oral imidazoles like
clotrimazole; nystatin
 Systemic infection requires amphotericin B or the
oral antifungal imidazole called fluconazole.

52. Aspergillus
52
 Monomorphic filamentous fungus
 Dichotomously branching
 Generally acute angles
 Frequent septate hyphae with 45° angles
 One of our major recyclers: compost pits, moldy
marijuana
 Medically important aspergillus are;
 Aspergillus flavus
 Aspergillus fumigatus
 They cause the same type of disease

53. Diseases of aspergillus
53
 Allergic bronchopulmonary aspergillosis
 The spores of Aspergillus mold are ubiquitous.
 Occurs in asthma, cystic fibrosis patients
 Type 1 hypersensitivity reaction (IgE-mediated immediate allergic
reaction) with bronchospasm, increase in IgE antibodies, and blood
eosinophilia.
 They can also manifest a type 4 reaction (delayed type cell-mediated
allergic reaction) with cell-mediated inflammation and lung infiltrates.
 Grows in mucous plugs without penetrating the lung tissue
 Systemic corticosteroids are an effective treatment+ itraconazole
 Aspergilloma (Fungus ball)
 Occurs in patients with lung cavitations from tuberculosis or
malignancies.
 It grows in preformed lung cavities, inducing cough
 This ball can be large (as big as a golf ball) and require surgical
removal.

54. Diseases of aspergillus
54
In immunocompromised patient with severe neutropenia,
Chronic granulomatous disease, Cardiac Failure, burns
 Invasive aspergillosis
 Invades tissues causing infarcts and hemorrhage.
 Invasive pneumonias and disseminated disease
 Nasal colonization causes pneumonia or meningitis while it causes
 Cellulitis in burn patients; may also disseminate
 Bloody sputum may occur, due to blood vessel wall invasion by Aspergillus
hyphae
 Treatment: Voriconazole for invasive and aspergilloma,
 Fungal toxins are called mycotoxins.
 The toxin produced by Aspergillus flavus and Aspergillus Parasiticus
is called the aflatoxin
 It causes liver damage and liver cancer.
 This has worldwide significance since Aspergillus grows
ubiquitously, contaminating peanuts, grains, and rice.
Other mycotoxins include: ochratoxin(nephrotoxic & respiratory tract
carcinogen), citrinin (nephrotoxic)

55. Pneumocystis jirovecii
formerly P. carini)
55
 A yeast like fungus (flying saucer-appearing fungi)
 Obligate extracellular parasite with a Silver stained cysts in tissues
 Based on IgM and IgG levels, it appears that about 85% of children
have had a mild or asymptomatic respiratory illness with Pneumocystis
carinii by age 4
 But causes pneumocystic pneumonia(Interstitial pneumonia) an atypical
pneumonia in the immunocompromised mainly in AIDS patients,
malnourished babies, premature neonates
 Pneumocystis carinii pneumonia (PCP) is the most common
opportunistic infection of AIDS patients. Without prophylactic treatment
there is a 15% chance each year of infection, if the CD4+ Thelper cell
count is below 200
 Symptoms: fever, cough, weight loss, night sweats shortness of breath;
sputum nonproductive(because sputum is too viscous to become
productive) except in smokers
 X-ray: patchy infiltrative (ground glass appearance); the lower lobe
periphery may be spared.

56. Pathogenesis, diagnosis and treatment
56
 Pneumocystis attaches to and kills Type I
pneumocytes, causing excess replication of Type II
pneumocytes and damage to alveolar epithelium.
 Serum leaks into alveoli, producing an exudate with a foamy
or honeycomb appearance on H & E stain.
 Silver stain reveals the holes in the exudate are actually the
cysts and trophozoites, which do not stain with H & E
 Diagnosis: Silver-staining cysts in bronchial alveolar
lavage fluids or biopsy
 Treatment: Trimethoprim/sulfamethoxazole for
mild;
Dapsone for moderate to severe

57. Mucor, Rhizopus, Absidia
(Zygomycophyta)
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 Non-septate filamentous fungi
 They are saprophytic mold present in the soil.
 Sporangiospores are inhaled
 Rhinocerebral infection
 (Old names: Mucormycosis = Phycomycosis =
Zygomycosis)
 Occurs in ketoacidotic diabetic patients and leukemic
patients
 Starts on nasal mucosa and invade the sinus and orbits
 Characterized by paranasal swelling, necrotic tissues,
hemorrhagic exudates from nose and eyes, and mental
lethargy
 Can also cause pulmonary mucomycosis
 These fungi penetrate without respect to anatomical
barriers, progressing rapidly from sinuses into the brain
tissue
 High fatality rate because of rapid growth and invasion

58. Diagnosis and treatment
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Diagnosis:
 Black nasal discharge
 KOH of tissue biopsy; broad ribbon-like
nonseptate hyphae with about 90° angles on
branches.
Treatment
 Debride necrotic tissue and start Amphotericin B
fast

59. THANK YOU FOR READING
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