1. Candida
Pathology

2. Introduction
• 4th Century BC – ‘Epidemics’ (by Hippocrates) mentioned oral aphtha
(Thrush)
• 200 species  20 A/W human or animal diseases
• Major pathogen – Candida albicans
• Others: C. dubliniensis, C. glabrata, C. guilliermondii, C.kefyr, C.kruesi,
C. lusitaniae, C. parapsilosis, C.tropicalis etc.
• Budding cells, psudohyphae and true hyphae – all simultaneously
possible

3. Pathogenesis
• Most common fungal infection in human
• Increased risk of infection –
• Extremes of age,
• Pregnancy,
• HIV infected,
• Steroid, cytotoxic drug (or similar) therapy,
• Malignancy,
• post transplantation,
• Broad spectrum antibiotics,
• Diabetes,
• neutropenia etc.

4. • Virulence factors
• Adhesins
• Enzymes: proteinases, phospholipase
• Toxins: GP extracts pyrogenic properties
• Pseudohyphae : Active infection marker

5. • Candida albicans transforms frequently between 3 phenotypic forms
in tissues  Phenotypic switching (evasion of host defence)

7. • Mostly endogenous source:
• GI,
• Vagina,
• Urethra,
• Skin,
• subungual
• Exogenous source: Catheters and lines, indwelling device  usually
deep seated systemic infection.
• Person to person transmission: Rare
• oral thrush in new-borns
• Sexual transmission

10. Mucosal candidiasis
Oral thrush Chronic mucocutaneous candidiasis

14. Cutaneous candidiasis
Onychomycosis and paronychia Intertrigo

19. Lab diagnosis
• Specimen: Depending on site – swabs (mucosal patches, skin lesion),
nail scrapings, sputum, blood, urine

20. • Direct Microscopy:
• Gram positive, oval budding yeast (4-6um) or KOH mount
• Pseudohyphae

21. • Pseudohyphae V/S true hyphae
Feature Pseudohyphae True Hyphae
Septa Constricted No Constriction
Origin of branches Constricted and septate No Constriction & No
septum present
Grows by Budding Apical elongation

23. • Culture: SDA with antibiotic, Blood agar, Blood culture bottle, CHROM
agaretc (@ 370C)
• Creamy white colony with yeasty odour after 24-48 hrs (SDA)
• Gram + budding yeast with pseudo-hyphae

25. Species identification
• Germ tube test: Reynold Braude phenomenon
• Colonies mixed with serum & incubated for 2 hours
• Wet mount under microscope
• Long tube like projections extending from yeast cells no constriction at
origin
• Specific for C. albicans (C. dubliniensis)

27. • Cornmeal agar:
• Chlamydiospore is specific for Candida albicans

28. • CHROME Agar
• Growth at 450C : C. albicans & C. dublinensis
• Sugar assimilation tests
• PCR

29. • Serology
• Antibody : ELISA, Latex agglutination
• ANTIGEN DETECTION: Cell wall mannan & Cytoplasmic antigen by ELISA
• Enzyme assay : Enolase, Proteinase
• Metabolites – alpha1-3 glucan (G test)

30. Treatment
• Depending on type of candidiasis
• Azoles
• Amphotericin B