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14 Cards in this Set

  • Front
  • Back
Clinical significance:

C.albicans classification:
C. albicans = most important fungal pathogen in man based on frequency, number of types of diseases and severity

Frequent cause of:
-diaper rash and thrush in infants
-severe infections in immunodepressed patients

Fungi imperfecti (deuteromycetes) - unknown sexual forms BUT recently have been shown capable of mating and cell fusion
Where is C.albicans located?
It is Endogenous

Located in human mucous membranes and digestive tracts, not free-living (usually exists peacefully with host)
C. albicans

Growth form on media:
Growth form with nutrient limitation:
Growth form in infection:
Growth form in tissue invasion:
stains gram +! (unlike most fungi)

budding yeast with vegetative hyphae beneath agar (no aerial hyphae), creamy white colonies

Chlamydospores form at the end of hyphae, pseudohyphae (elongated yeasts) form

Pseudohyphal and hyphal

Pseudohyphal and hyphal

Site of primary infection
C. albicans:

infects upper layers of stratified squamous epithelium (in oral cavity, tongue, esophagus, vagina, epidermis)
1) Oropharyngeal candidiasis
Develops often in whom and why?
Thrush =
Erythematous candidiasis =
Central Papillary atrophy of the dorsal tongue =
Angular cheilitis =
Mucositis (inflamm of mucosa) affects ~40% chemotherapy patients

Many patients with mucositis also develop candidiasis -> pain, inability to eat, increased infection risk

Thrush aka acute pseudomembranous candidiasis - white patches on mucosa

Erythematous - mild reddening of mucosa

Central Pap atrophy - flattening of tongue pappilae

Angular cheilitis - invasion of epithelium at corners of mouth
2) Esophageal candidiasis

3) Vaginitis and recurrent vulvovaginitis
invasion of esophageal epithelium

40% women have at least one, 20% asymptomatic carriers
Factors of immunity

DTH skin test
Primary host defense = epidermis and epithelium of mucosal surfaces
Cationic peptides: histatin in saliva, defensins in epithelium
PMNs: phagocytose and kill
Antibodies are NOT associated with protection

DTH skin test often used to establish normal host cell mediated response in general
Virulence factors:
which form is more invasive?
Hwp1 =
Hydrolytic enzymes:
Efflux pumps:
Hyphal and pseudohyphal forms: more invasive than yeast

Hwp1: Hyphal Wall protein 1
Present in hyphal forms, not yeast
mimics a mammalian epithelial cell protein and allows C. albicans to be cross-linked to mucosal surfaces via and enzyme (Transglutaminase)

from ALS gene family (large agglutinin-like sequence)
Permits attachment to mucosal and epithelial cells and host proteins (e.g. fibronectin)

degrade host proteins
SAPs (secreted aspartyl proteinases)and phosphatases for example

produced in the presence of azol drugs, leads to resistance

usually host's own organism, but can be orally and sexually transmitted, person to person in hospital outbreaks occur

Mucosal infections:
KOH mount, gram stain, histologic stain (C.albicans appears to graze on uppermost strat squamous epith)
Risk factors:
Alter oral mucosal environment:
Xerostomia (dry mouth), antibiotics, poor oral or denture hygiene, malnutrition/GI malabsorption, iron, folic acid, vitamin deficiency, carb-rich diets, heavy smoking, oral epithelial dysplasia

Alter immune status of host:
blood dyscrasias or advanced malignancy, old age/infancy, radiation/chemotherapy, HIV, endocrine abnormalities (diabetes mellitus, hypo/hyperthyroidism, pregnancy, corticosteroid therapy/hypoadrenalism

Increase rates of vaginal colonization:
higher glycogen level, enhanced vaginal epithelial cell avidity, increased germ tube formation by estrogen, high estrogen content of OC, uncontrolled diabetes mellitus, attendance at STC clinics, broad spectrum antibiotic usage/decreased bacterial flora

*lactobacillus levels reduced during candidiasis
Lab ID
Presumptive test:
Definitive test:
germ tube formation in serum within 1-2 hours (only yeast that does this within time limit at 37C)

Definitive: fermentation and assimilation of carbs and other compounds

prophylactic use may elicit drug resistance (Azole resistance has developed due to low levels of drug via mutation in target enzyme AND efflux pumps)

Azoles for mucosal infections -> inhibit ergosterol synthesis enzymes
Severe infections:
Amphotericin B

C. dubliniensis:
(importance, relation to albicans, growth forms)
C. glabrata:

Other Candida growth forms:
closely related to albicans (differs in repetitive DNA), found in HIV patients, forms germ tubes but less frequently than albicans

increasing incidence worldwide, intrinsically less susceptible to azoles and amphotericin B, doesn't form germ tubes or pseudohyphae
Along with albicans, account for 70-80% yeast isolated from candida infections

Other - form pseudohyphae, but no true germ tubes rapidly in vitro