Candida is a common yeast-like fungus that normally inhabits human skin and mucosa. It can cause infections, known as candidiasis, in individuals with weakened immune systems. The most common disease-causing species is Candida albicans. Candidiasis ranges from superficial mucosal infections to deep-seated invasive infections. Laboratory diagnosis involves microscopy, culture, and tests for species identification like the germ tube test or growth at 45°C. Treatment depends on the type of candidiasis and may include topical or oral antifungal azole drugs for superficial infections or amphotericin B for invasive infections.

1. CANDIDA
- DR. ANKUR KUMAR

2. CANDIDA SPECIES- INTRODUCTION
• CLASSIFICATION-
Yeast-like fungus
• Common Characteristics-
Unicellular fungi
Distribution- Candida spp. are normal inhabitants
of the skin & mucosa.
Reproduce by budding & fission
Macroscopic appearance- pasty colonies in
culture(resembling bacterial colonies)
Microscopic appearance- spherical or oval forms
in tissues and in culture. (filamentous structures –
pseudohyphae may be seen.)

3. Pseudohyphae
• Pseudohyphae-
In yeast cell, the bud
remains attached to the
mother cell, elongates and
undergoes repeated
budding to form chains of
elongated cells known as
pseudohyphae.
They can be differentiated
from true hyphae as they
have constriction at the
septa and bear septa even at
branching points.

4. Candida species
• Various species of Candida include:
 Candida albicans: It is the most common and most
pathogenic species of Candida infecting humans.
Non albicans Candida group- Other Candida species
which can occasionally cause infection includes-
C. tropicalis
C. glabrata
C. krusei
C. parapsilosis
C. dubliniensis
C. keyfr
C. guilliermondii
C. viswanathii
C. stellatoidea.

5. Candidosis/ Candidiasis/ Moniliasis
• Definition-
Candidosis refers to infection of skin, mucosa,
and various internal organs caused by yeast
like fungus- Candida albicans and occasionally
by other Candida species.
• Pathogenesis-
Candidiasis is worldwide in distribution,
accounts for the most common fungal
infection in humans, both in HIV and non-HIV
infected people.

6. Candidiasis
• Predisposing Factors-
increased risk of infection with Candida
associated with certain conditions:
Physiological state: Extremes of age (infancy, old
age), pregnancy.
Low immunity: Patients on steroid or
immunosuppressive drugs, post transplantation,
malignancy, HIV infected people.
Patients on broad spectrum antibiotics-
suppresses the normal flora.
Others conditions: Diabetes mellitus, febrile
neutropenia and zinc or iron deficiency.

7. Clinlcal Manifestations
• Candida species produce a spectrum of
infections ranging from skin and mucosal to
invasive and allergic infections & describes in
following headings-
Mucosal candidiasis
Cutaneous candidiasis
Invasive candidiasis
Allergic candidiasis

8. Mucosal candidiasis
The various mucosal manifestations include:-
Oropharyngeal candidiasis (oral thrush)
creamy-white, adherent, painless patches in
tounge or buccal mucosa, upon removal these
leave a red oozing surface. Frequently found
in bottle-fed infants, aged & debilitated
persons.
Candidal vulvovaginitis
characterized by pruritus, pain, and acidic
vaginal discharge that is usually thin, but may
become whitish curd like in severe cases.
Frequently found in pregnancy.

9. Mucosal candidiasis
Balanitis and balanoposthitis- occurring in
uncircumcised males.
Esophageal candidiasis
Angular stomatitis and denture stomatitis.
Chronic mucocucutneous candidiasis- seen in
infants and children with deficient CMI (T cell
defect). Lesions presents in hair, nail, skin, and
mucous membrane.

10. Cutaneous candidiasis
The following cutaneous manifestations are
produced in candidiasis.
 lntertriginous: It is characterized by erythema
and pustules in the skin folds associated with
tight fitting undergarments and sweating(eg.-
groin, perineum, axillae or inframammary folds).
Paronychia - involving nail-skin interface
Onychomycosis - fungal infection of nail.
Diaper candidiasis: Pustular rashes, associated
with use of diapers in infants.
Perianal candidiasis.
Generalized disseminated cutaneous candidiasis-
seen in infants.

12. Invasive candidiasis
It results from hematogenous or local spread of
the fungi. Various forms are-
Urinary tract infection
Pulmonary candidiasis
Septicemia (mainly by C. albicans and C. glabrata)
Arthritis and osteomyelitis
Meningitis
Ocular- keratoconjunctivitis and endophthalmitis
Hepatosplenic candidiasis
Disseminated candidiasis
Nosocomial candidiasis (mainly by C. glabrata)

13. Allergic candidiasis
Includes:-
Candidid:
This is an allergic reaction to the metabolites
of Candida, characterized by vesicular lesions
in the web space of hands and other areas,
similar to that of dermatophytid reaction
(both conditions are together called ‘id'
reaction).
Other allergic reactions include:
 Gastritis
 irritable bowel syndrome
 eczema.

14. Laboratory Diagnosis
• Specimen Collection-
various specimens can be collected such as
whitish mucosal patches, skin and nail scrapings,
sputum, urine or blood depending on the site of
infection.
• Direct Microscopy-
Gram staining reveals gram-positive oval budding
yeast cells (4-6 µm size) with pseudohyphae

15. Laboratory Diagnosis
• Culture-
Specimens can be inoculated onto SDA with
antibiotic supplements and then incubated at
370C.
Candida can also grow in bacteriological culture
media such as blood agar. Blood for culture can be
inoculated in to blood culture bottles.
 Colonies appear in 1-2 days and described as
creamy white, smooth and pasty with typical
yeasty odor.
Gram staining of the colonies shows gram-positive
budding yeast cells with pseudohyphae (except for
C. gtabrata which does not show pseudobyphae)

16. Tests for species Identification
• Germ tube test:
Also called Reynolds Braude phenomenon.
test is used for rapid method of identifying C.
albicans.
It is a specific test for C. albicans but also be
positive for C. dubliniensis &
Colonies are mixed with human or sheep serum
and incubated for 2 hours. Wet mount
preparation is examined under microscope.
Germ tubes are formed, described as long tube
like projections extending from the yeast cell. It is
differentiated from pseudohyphae as there is no
constriction at the origin.

17. Tests for species Identification
• Dalmau plate culture:
 Culture on cornmeal agar / Rice starch agar at
200c can provide clue for species identification.
 C. albicans produces refractile, terminal thick
walled chlamydospores.

18. Tests for species Identification
• CHROM agar:
Different Candida species produce different colored
colonies on CHROM agar…
 C. albicans- Light green
 C. dubliniensis- Dark green
• Growth at 450C:
It differentiates C. albicans (grows) from C. dubliniensis
(does not grow at 45°C).
• Sugar fermentation test and sugar assimilation test
differentiate between various Candida species.
• Molecular methods –
PCR using species specific primers are useful for species
identificacion.

20. lmmunodiagnosis
• Antibody detection:
Various formats like ELISA, latex agglutination tests
are available detecting serum antibodies against cell
wall mannan antigen.
• Antigen detection:
Candida specific antigen such as cell wall mannan and
cycoplasmic antigens can be detected by ELISA.
• Enzyme detection:
Assays are available to detect enzymes specific for
Candida such as enolase, aspartate proteinase, etc.
• Test for metabolites:
Specific metabolites of Candida such as mannitol,
arabinitol can be detected.

21. LABORATORY DIAGNOSIS- SUMMARY
• Direct microscopy: Gram positive oval budding yeast
cells with pseudohyphae.
• Culture on SDA: Produces creamy white and pasty
colony.
• Tests for species identification:
Germ tube test (positive for C. albicans)
Dalmau plate culture for chlamydospore production
CHROM agar
Growth at 45°C (positive for C. albicans)
Sugar assimilation test and sugar fermentation test
Molecular methods such as PCR •
• lmmunodiagnosis: -
Antibody detection against cell wall mannan antigen
Antigen detection such as cell wall mannan and
cytoplasmic antigens.

22. TREATMENT
• Eliminating possible predisposing factors.
• The antifungal drugs (Nystatin, Amphotericin B, 5-Fluorocytosine,
Ketoconazole, Miconazole, Fluconazole, Eechinocandins etc.)
recommended depends upon the type of
candidiasis-
Cutaneous candidiasis or oral thrush: the drug of
choice is topical azole.
Esophageal and vulvovaginal candidiasis: the drug
of choice is oral fluconazole.
Disseminated candidiasis: the drug of choice is
amphotericin B.
(C. glabrata and C. krusei exhibit intrinsic
resistance to azoles and are refractory to
treatment with azoles.)

23. THANK
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