Candida

Candida


Candida

  • Yeasts  like fungus
  • Most common cause of fungal infections worldwide.
  • Candida albicans is the most commonly isolated species.
  • C. albicans is a diploid fungus populating the human body worldwide
  • Inhabiting 80% of everyone’s intestinal tract, colon, and mouth with no problems.

Morphology:

  • It is dimorphic.
  • In Gram-stained smears, Candida appears as gram positive budding yeast cells (blastoconidia) 
  • Pseudohyphae showing regular points of constriction.
  • Spores form on the pseudohyphae called chlamydospores
  • C. albicans can take on either a unicellular (yeast) or multicellular (hyphae, pseudohyphae) form.

Culture:

  • Germ tube positive: 
  • Form germ tubes within two hours when incubated in human serum at 37°C
  •  Reynolds – Braude phenomenon /Germ tube test
  • They grow rapidly on simple media as oval budding cells at 25° to 37°C
  • Candida shows mycelia and chlamydospores on corn meal agar
  • Growth is inhibited by Griseofulvin
Virulence Factors
  • Adherence
  • Dimorphism
  • Germ tubes
  • Rapid switching of expressed phenotype
  • Surface hydrophobicity
  • Interference with phagocytosis, immune defences and complement
  • Extracellular hydrolases (Proteinases, lipases)
  • Synergism with certain bacteria
  • Killer toxins
  • Acidic metabolites
  • Growth rate and undemanding nutrient requirement
Pathogenicity:
  • Penetrates host mucosal surfaces the following morphogenesis into invasive filaments
  • Polymorphic growing pattern helps the yeast invade host tissue

By secreting various degradative enzymes:

  • proteinases
  • aspartyl proteases
  • phospholipases.

Phenotypic switching also plays a role in:

  • altering the yeast’s adherence properties
  • antigen expression
  • tissue affinity
  • adaptation.

Host predisposing factors: 

  • Long-term antibiotic therapy eradicating resident bacterial flora

Age:

  • Infants
  • Elderly are more susceptible

Disorders Which may predispose to mucocutaneous infections:

  • Diabetes mellitus: Most common risk factor.
  • Cushing’s syndrome
  • Addison’s disease
  • Hypothyroidism 
  • Immunodeficient conditions, inborn or acquired predispose to systemic infections
  • Women on contraceptives (oral or IUCD), pregnancy, menopause are more at risk of vaginitis
  • Neutropenia is the most prominent risk factors for invasive candidiasis

Exam Question

Candida
  • Yeasts  like fungus
  • Most common cause of fungal infections worldwide.
  • Inhabiting 80% of everyone’s intestinal tract, colon, and mouth with no problems.

Morphology:

  • It is dimorphic.
  • In Gram-stained smears, Candida appears as gram positive budding yeast cells (blastoconidia) 
  • Pseudohyphae showing regular points of constriction.
  • Spores form on the pseudohyphae called chlamydospores
  • C. albicans can take on either a unicellular (yeast) or multicellular (hyphae, pseudohyphae) form.

Culture:

  • Germ tube positive: 
  • Form germ tubes within two hours when incubated in human serum at 37°C
  •  Reynolds – Braude phenomenon /Germ tube test
  • They grow rapidly on simple media as oval budding cells at 25° to 37°C
  • Candida shows mycelia and chlamydospores on corn meal agar
  • Growth is inhibited by Griseofulvin 
Host predisposing factors: 
  • Long-term antibiotic therapy eradicating resident bacterial flora

Age:

  • Infants
  • Elderly are more susceptible

Disorders Which may predispose to mucocutaneous infections:

  • Diabetes mellitus: Most common risk factor.
  • Cushing’s syndrome
  • Addison’s disease
  • Hypothyroidism 
  • Immunodeficient conditions, inborn or acquired predispose to systemic infections
  • Women on contraceptives (oral or IUCD), pregnancy, menopause are more at risk of vaginitis
  • Neutropenia is the most prominent risk factors for invasive candidiasis
Don’t Forget to Solve all the previous Year Question asked on Candida

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