Candida

Candida

- small (4–6 m), oval,

-thin-walled

-yeastlike fungi that reproduce by budding or fission.

-comprised of over 200 species

-Only a few species cause disease in humans

• The medically significant Candida species include: Candida albicans, Candida (Torulopsis) glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei, Candida kefyr, Candida guilliermondii, Candida lusitaniae, C. stellatoidea, and Candida dubliniensis

Virulence Factors

-undergoes reversible morphological transition between budding pseudohyphal and hyphal growth forms.

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- Yeast cells may be disseminated more effectively, whereas hyphae are thought to promote invasion of epithelial and endothelial tissue and help evade macrophage

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-adherence to epithelial cells and proteins

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- Several genes and their products

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-sequence (ALS) family of protein encoding cell-surface adhesion glycoproteins (x-agglutinins)

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- HWP-1, which encodes a protein (Hwp1), an adhesin attaching to buccal epithelial cell

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-The ability of Candida species to overcome the suppressive effect of antifungal chemotherapy

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Esophageal Candidiasis

• increased because of AIDS, as well as the increased pool of transplant recipients, cancer and other severely immunocompromised patients.

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• Predisposing factors include exposure to local irradiation, recent cytotoxic chemotherapy, antibiotics, corticosteroids, and neutropenia

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• presents with dysphagia, odynophagia, and retrosternal pain. Constitutional findings, including fever, only occasionally occur.

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• Type I, a few white or beige plagues, up to 2 mm in diameter;

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• Type II, plaques are more numerous, larger than 2 mm in diameter;

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• Type III, confluent, linear and nodular elevated plaques with hyperemia and frank ulceration

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• Type IV, similar to Type III but with increased mucosal friability and occasional narrowing of the lumen

Gastric Candidiasis

• , Candida organisms are normal components of gastric flora.

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• Candida infections of the stomach are documented less frequently than in the esophagus, implying greater gastric mucosal resistance to Candida infection

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• pain, nausea and vomiting.

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• Cause Candida Enterocolitis and Diarrhea Syndromes

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• Increase in AIDS and Cancer cases

Cutaneous Candidiasis

• Candida can invade any body surface and cause superficial infection of the skin, hair

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• Dry intact skin is a potent barrier to fungal invasion, and hydration of the epidermis decreases resistance

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• These organisms favor growth in warm, moist areas such as the skin folds of obese individuals, between the fingers and toes, perineal areas, and genitocrural folds.

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Generalized Cutaneous Candidiasis

• This syndrome is a rare form of candidiasis that manifests as a diffuse eruption over the trunk, thorax, and extremities.

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• Patients have a history of generalized pruritus, with increased severity in the genitocrural folds, anal region, axillae, hands, and feet.

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• Examination reveals a widespread rash that begins as individual vesicles that evolve into large confluent areas

Chronic Mucocutaneous Candidiasis

• This syndrome involves multiple superficial sites, primarily the mouth, facial skin, hair and nails

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• Group 1 is chronic oral candidiasis associated with HIV

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• Group 2 comprises CMC associated with endocrinopathy and has also been called “Candida endocrinopathy syndrome”

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• Group 3 is localized CMC that is characterized by hyperkeratosis and cutaneous horn formation that affects both hands

Vulvovaginal Candidiasis

• Candida vaginitis is the second most common vaginal infection

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• Several factors are increased rates of asymptomatic vaginal colonization with Candida including pregnancy (30%– 40%), oral contraceptives with a high estrogen content, and uncontrolled diabetes mellitus

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• 10%–20% of asymptomatic, healthy women of childbearing age

Ocular Candidiasis

• access to the eye by one of two routes,
• either direct inoculation during eye surgery or trauma,

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• or as the result of hematogenous spread

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• Any eye structure may be involved including conjunctiva, cornea, lens, ciliary body, vitreous humor, and uveal tract.

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• Eye involvement may be unilateral or bilateral.

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• Lead to blindness if late in treatment

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Cardiac and Endovascular Candidiasis

• Candida myocarditis is the result of hematogenous dissemination with development of one or more abscesses within the myocardium.

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• Most frequently, abscesses are microabscesses usually diagnosed at autopsy.

Chronic Systemic Candidiasis

• Hepatosplenic candidiasis (HSC) is a chronic form of disseminated candidiasis

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• the term chronic systemic candidiasis since other organs (eyes, skin, and soft tissue) may be involved

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• reach submucosal blood vessels that drain into the portal venous system and then into the liver where focal Candida abscesses are established.

Neonatal Candidiasis

• The most serious of these syndromes is neonatal systemic candidiasis.

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• Developing either via ascending infection of the uterine contents prior to birth
• or from colonization acquired during passage through the birth canal

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• hematogenous dissemination of Candida presents in the first days or weeks of life with symptoms identical to those of neoa

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• In afew hours of birth with a diffuse maculopapular, erythematous rash involving almost any part of the skin

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Central Nervous System Candidiasis

• Cerebral parenchymal infection occurs as a single or multiple micro- or macroabscesses scattered throughout the brain

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• often difficult and frequently delayed in all age groups but especially in preterm low birth–weight neonates, resulting in considerable morbidity and mortality.

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Pulmonary Candidiasis

• found in sputum, and their role as a possible cause of pulmonary disease is a frequent clinical dilemma.

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• Two forms of Candida pneumonia

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• One form is local or diffuse bronchopneumonia as a consequence of bronchogenic spread

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• The second form is pneumonia resulting from widespread seeding of the lung in a patient with candidemia

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Urinary Tract Candidiasis

• Candiduria is a relatively rare finding in otherwise healthy people

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• the results of urine cultures were positive for 10 of 440 healthy adults

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• increased among hospitalized patients, especially those patients with indwelling drainage devices

Candida Infections in Burns

• Fungal infection is a serious complication of major burns

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• rates of candidemia ranging from 1.8% to 5%.

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• An additional risk is related to the surface area of the burn.

Laboratory Diagnosis

• ◗ Specimens These include exudates or tissues for microscopy obtained from skin or nails examined by microscope for demonstration of pseudohyphae or budding yeast cells of Candida.

• results are usually available in 48–72 hours

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• A positive culture only indicates that Candida species are present in the tissues examined.

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• CHROMagar Candida media allows for the presumptive identification of several Candida species by using color reactions in specialized media that demonstrate different colony colors,

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• the API 20C AUX, API 32C, Vitek 2 ID-YST, RapidID yeast Plus, and ID32C are several biochemical assays that allow the identification of the different Candida species

• Serologic assays include testing for Candida antibodies, antigens and metabolites.

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• (PCR) and DNA probes have the advantage of being able to detect small amounts of Candida DNA in either blood or tissues

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◗ Microscopy

• Gram-stained smear of the exudates or tissue shows Gram-positive, oval, budding yeast and pseudohyphae . Since Candida is found as a part of normal flora on normal skin or mucosa,.

• only the presence of large numbers of Candida is of significance. Demonstration of pseudohyphae indicates infection, and tissue invasion is of more diagnostic value

◗ Culture

• Culture on Sabouraud’s dextrose agar (SDA) produces typical creamy white, smooth colonies. Different Candida species are identified by their growth characteristics, sugar fermentation, and assimilation tests. Germ tube is a rapid method for identification of C. albicans and Candida dubliniensis.

• The basic culture media used in isolating clinical Candida species are blood agar , Potato Dextrose Agar ( PDA ) or broth ( PDB ) , Sabouraud brain heart infusion agar , Sabouraud Dextrose Agar ( SDA ) or broth ( SDB ) , Yeast Nitrogen Base ( YNB ) and Yeast Potato Dextrose ( YPD ) agar or broth . Lee's synthetic medium can be used for ...

Culture on blood agar

• Foot-like extensions from the margin�White creamy color

Green colonies

Nonculture Candida detection tests

• These include
• (a) Candida mannan assay,
• (b) Candida heat-labile-antigen assay,
• (c) D-arabinitol assay,
• (d) D-inositol assay,
• (e) 1,3-beta-D-glucan assay. Beta-Dglucan assay is a broad-spectrum test that detects Candida as well as Aspergillus

Treatment of Candida