1. INFECTIOUS DISEASE OF
PATHOLOGY
Fungus
Dr. Naila Awal
(Postgraduate student)

2. Definition
• Fungi are the eukaryotic, saprophytic,
parasitic micro organism, unicellular or
multicellular having chitin in their cell wall
& ergosterol & zymosterol in their cell
membrane.

3. Classification
Morphological classification1) Mold- fungi which are
structurally long
filamentous &
multicellular & form a
network of
hyphae/mycelium.
• Ex-
Dermatophytes
Aspergillus
Mucor --Aseptate
Septate

4. 2)Yeast- unicellular
round/oval like fungi
reproduction by budding.
3) Yeast like fungusFungus that reproduction
by budding, but bud fails
to separate from parent
cell & ultimately form a
structure that looks like a
chain of elongated cell.
They form
pseudohyphae.
• Ex- Cryptococcus
neoformans.
•
Ex- Candida

5. • 4) Dimorphic fungus
• Fungi that can remain
either mold/ yeast form
depending upon the
temperature of the
environment.
• Ex- Histoplasma
capsulatum
• 37C-->change to yeast
form
• 25C --> mold form

6. Depending upon the site of infection
1) Superficial mycosesThose fungal infection
,caused by the fungus that
lies on the surface of the
stratum corneum.
2) Cutaneous mycosescaused by the fungus that
liberate keratinase enzyme &
therefore can invade deep
into keratin layer of skin &
also nail &hair.
• ExMalassezia furfur -->
• Pityriasis versicolor
•
•
ExDermatophytes-->
dermatophytoses (Ring worm)

7. 3) Sub cutaneous
mycoses- caused by
the fungus that lies on
the surface of the
stratum corneum.
4)Deep mycoses- caused
by the fungus that infect
internal organ
• Ex• Rhinosporidium seeberi–
Rhinosporidioses.
• Ex• Candida–Candidiasis.
• Histoplasma capsulatumHistoplasmosis.

8. Superficial mycoses
(Pityriasis versicolor)
• Disease- Malassezia furfur
• Clinical manifestationLesions are macular, non-inflammatory, well
demarcated & hypopigmented.

9. Lab diagnosis
• Sample- Skin scrapping
• Lab procedure• The scrapping material is placed on glass slide few
drops of KOH is added cover slip wait for 20 mins.
• Observation-Cluster of rounded yeast cell & short ,stout,
curve, septate hyphae.

10. Cutaneous Mycoses
(Dermatophytes)
• Genus1)Trichophyton- Nail & Hair
2)Epidermatophyton- Nail
3)Microsporum- Hair
C/FSkin-->Ring like lesion.
Ring- Scaly, hypopigmented & inflammatory.
Nail yellow, brittle & thick.
Hair brittle.

11. Lab diagnosis
• SampleSkin- Skin scrapping
Hair- Hair clipping. If infection present in scalp, then skin
adjoining scalp is taken.
Nail Nail shaving at the margin between healthy &
unhealthy area & from the deeper portion of nail.

12. Lab procedure
1)The material is placed on glass slide few drops of KOH
is added cover slip wait for 30 mins (skin)/10mins
(hair)/several hours.
• Observation- long thin, branched & septate hyphae.
2) Culture- Sabouraud's dextrose agar media25-28 C for 3-4 weeks.
• Colony morphology- colony is picked up place on
glass slide Lacto phenol cotton blue dye is added
cover slip examine under microscope.

13. • Spiral Hyphae
Tinea
mentagrophytes
• Anthar hyphaeTinea
schoenlenii
• Macroconidia
Microsporum
• Microconidia
• Trichophyton rubrum

14. Sub cutaneous mycoses
Mycetoma
• Definition- It is a granulomatous disease of
•
•
•
•
subcutaneous tissue caused by various fungi & bacteria
where there is gradual destruction of tissue leading to
loss of function of the affected area.
Disease- Maduromycosis /Madura foot
Actinomycetoma when madura foot is caused by
bacteria.
Eumycetoma when madura foot is caused by
fungus.
Site- 1)Foot most common site
2)Lower extremities
3)Back

15. • Clinical manifestation1)Suppuration
2)Abscess formation
3)Granuloma
4)Tumor like swelling containing multiple draining sinus.

16. Pathogenesis
• Local trauma of skin
Micro organism enters to the body
Inflammatory response
Granulomatous inflammation.

17. Lab diagnosis
• Sample- muco pus
• Lab procedure• Muco pus is taken in 3 separate glass slides.
• 1st slide- 1 drop of normal saline is added cover slip
viewed by hand glass
• Observation• If granules are black- Madurella grisea
red-Madurella mycetomatis
yellow white-Pseudallescheria boydii

18. 2nd glass slide
• Add few drops of 20% KOH in muco pus wait for 10
mins
• Observation• If fine fillamentous branch with no chlamydospore
Bacteria
• If thick septate branched hyphae with chlamydospore
Fungus

19. 3rd glass slide• Granules are crushed on a slide Z-N stain
decolorized with 1% H2SO4 Red branching filament
Nocardia

20. • HistopathhologySuppurative granuloma• Center abundant polymorphonuclear cells & granules
• Surrounded by --lymphocytes, plasma cell, histiocytes &
fibrosis.

21. Rhinosporidiosis
• Definition- It is a chronic granulomatous disease
characterized by production of large polyp / wart like
lesion.
• Causative organism- Rhinosporidium seeberi
• Site- Common site –Nose-78%
Nasophaynx-68%
Tonsil-3%
Eye-1%.

22. Pathogenesis
Local trauma
Fungus is inoculated into the mucosal epithelium of nasal
cavity
Replication of fungus
Hyperplasic growth of host tissue & immune response
Granulomatous disease

23. Morphology
• The lesions are polypoid, reddish & granular.
• May be multiple & pedunculated.
• Highly vascular & bleed on touch.
M/E• Papillomatous hyperplesia of nasal mucosa.
• Multiple mature & immature cyst (sporangia) are packed
with spores.
• Infiltration of chronic inflammatory cells into normal
tissue.

25. Deep Mycoses
• ClassificationDeep mycoses
Primary deep mycoses
Opportunistic mycoses
(Fungal infection that
infect healthy Individual)
Ex
Coccidioidomycosis
Paracoccidioidomycosis
Histoplasmosis
Blastomycosis
(Fungal infection that
infect immunosuppressive individual)
ExCandidiasis
Cryptococcosis
Aspergillosis
Mucormycosis

26. Histoplasmosis
• Causative organism- Histoplasma capsulatum.
• Pathogenesis• Source of infection- Soil
• Mode of transmission- Inhalation.
Through inhalation
macro & microconidia enters into lung
engulf by alveolar macrophage
through macrophage they spread to the various tissue.
(Liver, spleen, lymph node)

27. • C/F1)Asymptomatic
2)Pulmonary histoplasmosis- fever, dry cough.
More severe case- granulomatous lesion in lung.
3)Localized lesion in extrapulmonary sitemediastinum, adrenal,liver, meninges.
4) Disseminated histoplasmosis- Immunosuppressed
person.

28. Lab diagnosis
• Specimen1)Pulmonary histoplasmosis- Sputum.
2)Buffy coat of blood.
3)Bone marrow aspirate.
4)Biopsy specimen from different internal organ.
• Lab procedure• 1) Direct microscopy- Specimen is taken on the glass
slide Giemsa staining Microscopic examination.
• Findings- Yeast like fungus within the cytoplasm of
macrophage.

30. 2)CultureSabouraud’s dextrose agar media- incubate at 37 C for 4
weeks.
Observation of colony morphologyhyphae with macro & micro conidia.
3) SerologyPatient’s serum-Anti histoplasma
capsulatum .
4)SkinHistoplasmin skin test.

31. 5) HistopathologyPulmonary histoplasmosisEpithelioid granuloma with
central caseous necrosis,
which coalesce
to form
areas of consolidation.
Disseminated histoplasmosis-->Mononuclear phagocytes filled with fungal yeast.
-->Epithelioid granuloma are not formed.

32. Cryptococcosis
• Definition- It is a true yeast surrounded by thick
polysaccharide capsule.
• Causative organism- Cryptococcus neoformans.
• Nice to knowCapsulated bacteriaStreptococcus pneumoniae
Klebsiella
Haemophillus influenzae
Neisseria meningitidis

33. Mode of transmission- Inhalation of yeast
.
• Pathogenesis• It is asymptomatic / produce influenza like
symptoms which resolves automatically in
healthy person.
But in immunocompromised person Through inhalation enters into lung via
blood meninges cryptococcal meningitis.

34. Lab Diagnosis
• Specimen1)CSF
2)Sputum
3)Tissue sample
Lab procedure1)Wet film microscopy- circular/oval yeast cell.
2)India ink preparation- CSF is centrifuged deposit is
taken on glass slide1 drop of india ink is added
cover slip examine under microscope.
Observation- against dark background darkly illuminated
single circular/oval yeast with budding.

36. 3) Culture-
Blood agar media- 37 C for 24 hours
Saborauds dextrose agar media-37 C for 2 days.
• 2 days after, colonies are picked up on glass slide
examine under the microscope
• ObservationSpherical yeast cell
with budding.
4)Serological test- Anti cryptococcal Ab +

37. Histopathological findings
• CNS• In immunosuppressed personSoap bubble lesion- gelatinous masses of fungi in
meninges or may expand the perivascular VirchowRobin space within the grey matter.
• In non immunosuppressed personChronic granulomatous lesion composed of macrophage,
lymphocyte & foreign body giant cell. Suppuration may
also occur.
• Lung- Solitary pulmonary granuloma.

38. Aspergillosis
• Causative agent- Aspergillus fumigatus.
• Mode of transmission- By the inhalation of
Aspergillus spore.
• Spectrum of disease1) No infection- b/c alveolar macrophage engulf & destroy
the conidia.
2)Person who have allergic to Aspergillus antigen, manifest
as Allergic bronchopulmonary Aspergillosis (ABPA).
3)Person who have cavity to lung (due to TB, sarcoidosis),
conidia after reaching the cavity they germinate &
produce abundant hyphae in lung cavity. This clinical
condition is known as Aspergilloma.

39. • They manifest asHaemoptysis
Dyspnoea
Asthma

40. 4)Person who are in steroid therapy (leukemia, bone
marrow transplantation) inhale conidia produce
severe manifestation of disease Invasive
Aspergillosis which is clinically manifest as pneumonia.
• After lung infection hyphae invade blood vessels
haematogenous spread to different internal organ
Abscess (brain, liver, kidney).

41. Lab diagnosis
• Sample1)Sputum
2)Blood
3)Lung biopsy.
• Lab procedure• 1) Gram staining- Septate hyphae
with dichotomous branching.
• 2)CultureBlood agar
Sabouraud's dextrose agar media

42. • Observation of colony- Aspergillus colonies are usually
fast growing, white, yellow, yellow-brown, brown to black
or shades of green.
• 3) Serological test- Immunodiffusion tests for the
detection of antibodies to Aspergillus species .
• 4) Histopathology• AspergillomaProliferative mass of hyphae form fungal ball which lies
freely within the cavities.
 Surrounding inflammatory reaction may be
sparse/chronic inflammation/ fibrosis.

43. Invassive aspergillosis
• 1) lungAspergillus form fruiting bodies (usually in lung cavities) &
Septate filaments, branching at right angles (40 degrees)

44. Mucormycosis
Definition- It is an opportunistic infection caused by ‘bread
mould fungi’ including- Mucor, Rhizopus, Abscidia &
Cunninghamella.
Predisposing factors•
•
•
•
•
Neutropenia
DM
Corticosteroid use
Iron overload
Breakdown of cutaneous barrier as a result of burning,
surgical wound/ trauma.

45. Major route of infection- 1) Inhalation
2) Ingestion
3) Traumatic inoculation.
Clinical presentation• 5 clinical form of Mucormycosis- Rhino cerebral,
pulmonary, gastrointestinal, primary cutaneous &
Disseminated.
• Rhino cerebral MucormycosisInitial symptoms- acute sinusitis, congestion, purulent nasal
discharge, fever, unilateral headache, peri orbital edema,
proptosis, facial numbness, cranial nerve palsy.

46. • Pulmonary MucormycosisFever, haemoptysis
• Gastrointestinal Mucormycosis• Bowel perforation, peritonitis, GIT hemorrhage.
• Severe immunocompromised person manifest as
primary cutaneous lesion.
• They do not harm in immunocompetent
individual but infect immunosuppressed person.

47. Pathogenesis
• It is transmitted by air borne asexual spore.
• After inhalation of spore
Colonize into nasal sinus
Orbit
Brain
Rhino cerebral
Mucormycosis
Lung
Engulf by alveolar macrophage
& oxidative killing

48. Lab diagnosis
• Specimen- Biopsy from suspicious areas.
• Lab procedure1) Staining• H&E stain- often hard to see
– GMS, PAS stains better
Observation-Non septate,
irregularly wide fungal
hyphae with frequent
right angle branching.

49. 2) Histopathology- Common site• nasal sinus, lung &GIT
Rhino cerebral Mucormycosis• Local tissue necrosis
• Invade arterial wall
• Penetrate peri orbital tissue.
• Pulmonary Mucormycosis• Areas of hemorrhagic pneumonia with
• Vascular thrombi &
• Distal infraction.

50. Candidiasis
• Species1)Candida albicans.
2)Candida tropicalis.
3)Candida parapsilosis.
• Features1) Dimorphic fungus•
•
25 C-True hyphae.
37C-Pseudohyphae with yeast.
2) May
produce chlamydospore- Sexual spore.
3) Causes opportunistic infection.

51. • Predisposing factor of candidiasis1) Immunosuppression due to prolong use of – Anti cancer
drug, steroid.
2)AIDS
3)Prolong use of antibiotic
4)DM
5)Pregnancy
6)Bone marrow transplant recipient
7)Leukaemia, lymphoma
8)Very young & very old age.

52. Clinical spectrum of candidiasis• 1) Mucosal candidiasis•
•
•
Oral thrush
Candida esophagitis
Vulvo vaginal candidiasis
•
•
•
•
•
•
•
2) Cutaneous CandidiasisNail proper- Onychomycosis
Nail fold- Paronychia
Armpit/ web of the fingers & toes- Intertrigo
Hair follicle- Folliculitis
Penile skin- Balanitis
Perineum of infant- Diaper rash

53. 3) Chronic muco cutaneous candidiasis• It involves superficial skin & mucous membrane.
4)Invasive candidiasis-

54. Oral thrush
• Definition- It is the superficial fungal infection on the
mucous membrane of oral cavity.
• Seen inNewborn
Debilitated people
Children receiving oral steroid
 HIV positive patient
for asthma & following a course of
broad spectrum antibiotics that destroy normal bacterial flora.
• Morphology- They form grey-white dirty looking pseudo
membrane, composed of matted organism &
inflammatory debris.
• Deep to the surface there is mucosal hyperemia &
inflammation.

55. Candida esophagitis
• Commonly seen inAIDS patient
Hematolymphoid malignancy.
• Clinical presentationDysphagia
Retrosternal pain.
• Endoscopic findingsEsophageal mucosa-- plaque & pseudo membrane.

56. Vaginal candidiasis
• Common in• Women withDM
Pregnancy
Taking OCP
• Clinical manifestationIntense itching
Thick curd like discharge

57. Invasive candidiasis
• Definition- It is a candidiasis which is caused
by blood borne dissemination of organisms into
various tissue / organs.
• Persons risk for developing candidiasis1) ICU patient
2) Surgical patient
3)Patient with central venous catheter
4) Immunocompromised person.
5) Very LBW infant

58. • Common pattern/ Effect1) Kidney- Renal abscess
2) Heart- Myocardial abscess & endocarditis.
3)CNS- Brain micro abscess & meningitis
4) Liver- Hepatic abscess
5) Eye- Endopthalmitis
Findings Inflammatory response
 Occasionally granuloma.

59. Lab diagnosis of candidiasis
• Sample-->Swab
-->Scrapping from superficial lesion
-->Tissue biopsy
-->Exudates
-->Blood, CSF, Urine
-->Material from I/V catheter

60. Lab procedure
1) Wet film preparation- From
Swab, exudates, CSF (centrifuge), urine (centrifuge)
• FindingsSpherical/ oval yeast cell with budding.

61. 2)StainingA) Gram staining- Gram + round/oval yeast cell with
budding.
B) Immuno fluorescence staining- calcoflor white stain.
3) CultureA) Sabouraud's dextrose agar media
B) Blood agar media
• 37 C for 48 hours in aerobic condition.

62. Colony morphology• 2-4 mm in diameter, circular, white/creamy, soft with
mucor odor.
4)Confirmation – Gram staining from the culture plate.
• Gram + yeast with budding.

63. 5)Germ tube test (Confirmatory test for Candida albicans)
• 0.5ml human serum is taken in a test tube
• Test fungal colony is added
• Incubate at 37C for 4 hours
• Then 1 drop of serum is collected & place on glass slide
• Cover slip
• Microscopic examination

64. • Observation- Yeast like cell with finger like projection.
• Comment+ for Candida albicans
7) Sugar fermentation test• It differs for different species.