Mycology

1. INSTITUTE OF HEALTH TECHNOLOGY, DHAKA
Department of Laboratory Medicine
BSc in Health Technology (Laboratory)- 1st Year
MYCOLOGY
Lecture No. 7.1 (Opportunistic Mycoses -Candidiasis)
By
Sk. MIZANUR RAHMAN
Lecturer, Mycology
MS in Biotechnology & Genetic Engineering (UODA)
MS in Microbiology (SU)

2. Candidiasis - an infection caused by a Candida spp.
Candida is a yeast and is is part of the normal flora (commensal)
of the skin, mouth, vagina and GI tract.
Antibiotic treatment can alter the normal bacterial flora
allowing Candida to flourish.
Thrush - a superficial Candida infection of the mouth or vagina.
Opportunistic Mycoses-Candidiasis

3. Candida is the most common cause of opportunistic mycoses
worldwide.
Candida albicans is the most pathogenic and most commonly
encountered species
Systemic candidiasis is common in the immunocompromised
(AIDS, chemotherapy, post-surgery)
Disseminated infections arise from hematogenous spread from
the primarily infected locus
Candidiasis

4. Species include:
o Candida albicans (the most important)
o Candida tropicalis
o Candida krusei
o Candida parapsilosis
o Candida glabrata
o Candida dubliniensis
Candidiasis

5. Oral candidiasis (Oral thrush)
• Classic thrush is characterised by a white, curd-like coating on the
tongue or elsewhere in the oral cavity. Stomatitis due to Candida is
often associated with painful infection of the lips - and corners of
the mouth.
Genital or perigenital candidiasis ((vulvo vaginitis)
• (vulvo)vaginitis due to Candida .
• Contamination of the vagina with Candida stems from the
endogenous endosaprophytic flora of the gastro-intestinal tract.
Diagnoses
– in culture, it grows as blastospores, pseudohyphae, and septate
hyphae
– Candidiasis the collective term for infection involving Candida
• cutaneous
• vaginal
• systemic
Candidiasis

6. In normal host, candida albicans may cause:
1) Oral thrush or moniliasis (patches of creamy white
exudate that cover the mucous membrane of the
mouth).
2) Vulvovaginal moniliasis: itching and cheese appearing
vaginal discharge. It occurs in females with:
o Prolonged use of broad spectrum antibiotics
(superinfection)
o Contraceptive pills
o Pregnancy
3) Rash in the skin folds
4) Diaper rash.
5) Paronychia of the nails (thickening and loss of the nails).

7. Oral Thrush- the white material consists of
budding yeast cells and pseudohyphae.
Mucocutaneous Candidiasis-
granulomatous lesions involving the hands.
Candidiasis

8.  Gram positive, oval budding yeast cells.
 If buds fail to detach, they form pseudohyphae.
 Pseudohyphae are differentiated from true hyphae
by the presence of constrictions at septations
between the cells.
 But, Candida glabrata does not form pseudohyphae.
Candidiasis-Characteristics

9. Candida

10. Oral thrush

11. Vulvovaginal moniliasis
Rash in the skin folds

12. Diaper rash
Paronychia

13.  In immunocompromised individuals such as:
1) Esophageal thrush.
2) Chronic mucocutaneous candidiasis.
3) Systemic or disseminated candidiasis (even to the eye).
AIDS
Diabetes
mellitus
Malignancy
Defect in cell mediated immunity
Corticosteroids
Catheters

14. Candidiasis

15.  Specimen: according to the site of the lesion.
 Direct examination of Gram stained smear: Gram
positive oval budding yeast cells + pseudohyphae.
Candidiasis-Laboratory Diagnosis

16.  Culture: on SDA at 37 degree.
 Identification of candida on the plate is done by:
1. Morphology: soft cream colored colonies with yeasty
odor.
2. Gram film: Gram positive oval budding yeast cells.
Candidiasis-Laboratory Diagnosis

17. 3. Biochemical reactions: to differentiate between
Candida albicans and other species.
o Germ tube test: Candida albicans forms germ tube
when incubated in serum for 1 – 2 hour at 37 degree.
o Chlamydospore formation: Candida albicans forms
chlamydospores on corn meal agar incubated at 30
degree.
o Sugar fermentation: Candida albicans ferment glucose
and maltose with acid and gas production.
o Inoculation of the yeast on chromogenic agar: each
candida species produces a different color on this
medium.
Candidiasis-Laboratory Diagnosis

18. Germ tube
Chlamydospores CHROMagar