3. Candida albicans Gen.
Characteristics





Agent of yeast infections
Premier cause of yeast infection in the
world
Oval yeast with a single bud
Thin walled, reproduce by budding or
fission
Normal flora
◦ Upper respiratory, gastrointestinal, female
genital tracts, mucosa, skin, and digestive
tract

In tissues, appear as budding yeasts or

4. Candida albicans. Notice the spherical chlamydoconidla (resting bodies formed from hyphal cells)
and the smaller blastoconidia (asexual spores produced by budding).

5. Microscopic features
-almost complete sexual budding
C. albicans in mycelial or
tissue phase with
blastoconidia budding from
the pseudohyphae.
Microscopic morphology of
C. albicans showing budding
spherical to ovoid
blastoconidia.

6. Methods of Identification


Production of germ tubes by C.
albicans



Germ Tube Test (+) w/
capsule
◦ A rapid screening test for
Candida albicans and Candida
dubliniensis.
◦ 0.5 mL of serum, containing
0.5% glucose, is lightly
inoculated with the test
organism and incubated at 37°C
for 2-3 hours.
On microscopy, the production of
germ tubes by the cells is
diagnostic for Candida albicans.
sugar assimilation profile
distinctive green colour on
CHROMagar.
production of chlamydospores
(corn meal agar @ 20°C)

7. Methods of Identification
CHROMagar Candida plate showing chromogenic colour change for C. albicans (green), C.
tropicalis (blue), C. parapsilosis (white) and C. glabrata (pink).

8. Pathogenicity:
 Candidiasis
is an acute-to-chronic fungal
infection that can involve the
mouth, vagina, skin, nails, bronchi, lungs
, alimentary tract, bloodstream, or
urinary tract.
 Most widely recognized manifestation
of C. albicans is THRUSH, an infection of
oral mucosa which is also an indication
of immunosuppression.

9. Candidiasis

Oral thrush
- is a yeast infection that forms
white curd-like patches on the
oral mucocutaneous membranes.
Vulvovaginitis/ vagina thrush
- as a thick yellow-white
discharge.
- Diabetes, antibiotic
therapy, oral contraceptives, and
pregnancy predispose the
patient to this condition.
- Due to loss of lactobacilli the C.
albicans flourishes


10.  Cutaneous candidiasis
- Occurs in chronically
moist areas of skin
and in burn patients.
- Onychomycosis and
paronychia
-Chronic
mucocutaneous
candidiasis
 Cadidemias
- occur in patients who
have indwelling
catheters.

11. Viability:





DRUG SUSCEPTIBILITY
- Sensitive to
nystatin, miconazole, clotrimazole, ketoconazole, fluconaz
ole, amphotericin B for invasive candidiasis
DRUG RESISTANCE
- Resistant strains have been described for all the above
antifungal drugs
SUSCEPTIBILITY TO DISINFECTANTS
- Sensitive to 1% sodium hypochlorite, 2%
glutaraldehyde, formaldehyde; only moderately sensitive
to 70% ethanol (phenolic may be substituted)
PHYSICAL INACTIVATION
- Inactivated by moist heat (121°C for at least 15 min)
SURVIVAL OUTSIDE HOST
- Survives outside of host, especially in moist, dark areas

12. Mode of transmission:
Normal
flora of oral cavity, genitalia,
large intestine or skin of 20% of humans
80% of nosocomial fungal infections
Endogenous spread (part of normal
human flora); by contact with
excretions of mouth, skin, and feces
from patients or carriers; from mother
to infant during childbirth; disseminated
candidiasis may originate from mucosal
lesions, unsterile narcotic injections,
catheters.

13. Prevention & Control:
 Keeping
your skin clean and dry, by using
antibiotics only as your doctor directs, and
by following a healthy lifestyle, including
proper nutrition.
 People with diabetes should try to keep
their blood sugar under tight control.
 HIV or another cause of recurrent episodes
of thrush, then antifungal drugs such as
clotrimazole (Lotrimin, Mycelex) can help
to minimize flare-ups.

14.  For
local infection, removal of the cause
(eg. Moisture) & administration of
antimicrobial agents are effective.
 Tropical cream (eg. Nystatin & miconazole)
 For systemic infection- oral ketoconazole
can control mucocutaneous candidiasis.
 For disseminated candidiasis- intravenous
amphotericin B, oral flucytosine or oral
ketoconazole can be effective if cellular
immunity.

16. GENERAL
CHARACTERISTICS







2nd most common isolated fungus after
Candida
A. fumigatus is the specie most commonly
isolated
Pathogenic species are A. flavus, .A.
terreus, & A. niger
Fast growing fungus
Not dimorphic and producing septate hyphae
Spores are constantly present in the air
Does not cause disease, except for
immunocompromised person w/ 90%
mortality

17. Morphology
May be either uniseriate or biseriate
 Arise from a “foot cell”, a vegetative
hyphae
 Uniseriate

◦ Phialides attached to the vesicle at the end
of conidiophore

18. Morphology

Biseriate
◦ Posses a supporting structure called
metula
◦ Metulae attached directly to the vesicle, &
attached to each metula are phialides
then eventually conidia are produced.

19. Morphology





Color of the fungus comes from the
conidia, asexual spore.
Colors are
black, white, yellow, brown, tan, green, gray, be
ige, pink, but most pathogens are green to
tan colored.
“Fungus balls” in the lungs of agricultural
workers who routinely are in contact w/ fungal
conidia from environmental sources. This can
be seen through X-ray and can be removed
through surgery.
Erect conidiophore arising from a foot cell
Conidia can be aligned in very
straight, parallel columns or in radiant
pattern around the vesicle and it can be
rough or smooth.

20. Aspergillus fumigatus
Most important pathogen
 Can colonize and later invade abraded
skin, wounds, burns, the cornea, the
external ear, or paranasal sinuses.
 may grow at temp. range of 2050°C, best grow at 40-45°C

◦ Produces conidial heads w/ numerous
conidia
◦ Hyphae are septate
w/ dichotomous branching

21. Aspergillus flavus
Growing on cereals or nuts
produces aflatoxins that may be
carcinogenic or acutely toxic
especially biserate or
• Uniserate or in the liver both w/ phialides

covering the entire spherical vesicle
• Conidia are globose to subglobose (3-6
um in diameter), pale green and
conspicuously echinulate. Some strains
produce brownish sclerotia.

22. Aspergillus niger


Beano™ is an enzyme
preparation from A. niger
that breaks down CHO
typically found in
beans, Cabbage, broccoli
and other high fiber foods
which are tending to
produce flatulence as a
result of microbial action in
the intestines.
Biserate w/ phialides
covering the entire surface
of the spherical vesicle;
conidia are black

23. Microscopic features
SPECIES
CONIDIOPHORE
PHIALIDES
A. clavatus
Long, smooth
Uniseriate
A. flavus
Colorless, rough
Uni-/biseriate
Round, radiate head
A. fumigatus
Short (<300 µm), smooth,
colorless or greenish
Uniseriate
Round, columnar
head
Uniseriate
Round, radiate to
very loosely
columnar head
A.
Variable length, smooth,
glaucus grou
colorless
p
VESICLE
Huge, clavateshaped
A. nidulans
Short (<250 µm), smooth, brown Biseriate, short
Round, columnar
head
A. niger
Long, smooth, colorless or brown Biseriate
Round, radiate head
A. terreus
Short (<250 µm), smooth,
colorless
Biseriate
Round, compactly
columnar head
Biseriate
Round, loosely
radiate head
A. versicolor Long, smooth, colorless

24. Colony Identification
SPECIES
SURFACE
REVERSE
A. clavatus
Blue-green
White, brownish with
age
A. flavus
Yellow-green
Goldish to red brown
A. fumigatus
Blue-green to gray
White to tan
A. glaucus group
Green with yellow areas Yellowish to brown
A. nidulans
Green, buff to yellow
Purplish red to olive
A. niger
Black
White to yellow
A. terreus
Cinnamon to brown
White to brown
A. versicolor
White at the beginning, White to yellow or
turns to yellow, tan, pale purplish red
green or pink

25. Identification
Growth is rapid to moderately rapid
(colonies may be seen in 4 days)
 Powdery in texture
 A. nidulans and A. glaucus slowly
grows, in 7 days reaching 0.5 -1cm at
25°C


26. A. clavatus
A. flavus

27. A. glaucus
A. fumigatus

28. A. niger
A. nidulans
A. terreus

29. Pathogenecity=Aspergillosis

Invasive aspergilloma
◦ Neutropenia is the single most predictive factor for
developing this Dse.
◦ The Px has sinusitis, & dissemination throughout the
body
◦ There may be high titers of galactomannan Ag in
serum
Aspergillus spp. Are the frequent cause of
disease in the bone marrow transplant recipient
in addition to other cancer transplant Px.
 Allergic aspergillosis

◦ High titer or IgE Ab against Aspergillus is detected
◦ Infection is initiated as the fungal conidia were
inhaled, thus airborne
 In the lung air spaces, conidia begin to germinate and
invade tissue

30. Pathogenecity
Conidia in the earwax can lead to a
painful ear Dse known as Otomycosis
 Common to people with Asthma or
cystic fibrosis
 Invasive type only affects
immunocompromised patients
 Can cause multiple organ involvementbrain, liver, heart, and bone producing
hemoptysis and granulomas


31. Symptoms







w/in the few days, Px
develops a severe fever
that fails to response to
anti-fungal therapy
Pneumonia like symptoms
are possible
Wheezing (as in asthma)
Coughing
Chest pain
Shortness of breath
Aspergilloma/ “Fungus
balls”
Fungus balls

32. Treatment
Voriconazole -first-line treatment for
invasive aspergillosis.
 Amphotericin B for invasive aspergillosis
 Itraconazole
 Lipid Amphotericin Formulations
 Caspofungin
 Micafungin
 Posaconazole
**immunosuppressive
medications should be
discontinued or decreased.


33. Prevention
Wear an N95 mask when near or in a
dusty environment such as construction
sites
 Avoid activities that involve close contact
to soil or dust, such as yard work or
gardening
 Use air quality improvement measures
such as HEPA filters
 Take prophylactic antifungal medication if
deemed necessary by your healthcare
provider
 Clean skin injuries well with soap and
water, especially if the injury has been
exposed to soil or dust


34. Thank you for listening! 