Candidiasis – Definition, Causative Agent, Types, Transmission

Candidiasis, also known as a yeast infection, is a fungal infection caused by a group of yeasts called Candida. Candida is a normal part of the human microbiota and is commonly found in the mouth, gut, and female genital tract. However, when there is an overgrowth of Candida, it can cause infection.

Candidiasis can occur in many parts of the body, including the mouth (oral thrush), skin (cutaneous candidiasis), vagina (vaginal yeast infection), and bloodstream (invasive candidiasis). Symptoms depend on the location of the infection and can include itching, burning, and redness.

Risk factors for candidiasis include a weakened immune system, diabetes, antibiotic use, pregnancy, and certain medications such as corticosteroids. Treatment typically involves antifungal medications, either topically or orally, and addressing any underlying medical conditions that may be contributing to the overgrowth of Candida.

Candidiasis definition

• Candidiasis is an opportunistic infection induced by Candida, a type of fungi. As yeasts, moulds, or dimorphic fungi, fungi are eukaryotic organisms. Candida is a form of yeast. Candidiasis occurs most commonly as a secondary infection in immunocompromised individuals. Candidasis is synonymous with candidosis, moniliasis, and thrush.
• These are prevalent residents of the oral cavity, digestive tract, vaginal penis, and other areas. They only become pathogenic under optimal conditions. It can affect the oral cavity, vagina, penis, and other organs. Candidiasis of the mouth is commonly referred to as thrush.
• It presents as white patches on the tongue, throat, and other mouth areas. Additionally, soreness and difficulty ingesting are symptoms of thrush. When Candida infects the vagina, the condition is known as a yeast infection.
• Oral candidiasis can be pseudomembranous, erythematous, and chronic hyperplastic candidiasis. Pseudomembranous candidiasis is common in infants and chronically ailing patients.
• It is exhibited as white, soft, slightly elevated plaques most commonly on the tongue and buccal mucosa.
• Plaques resemble curd and consist of tangled aggregates of fungal hyphae with intermingled desquamated epithelium, necrotic debris, keratin, leukocyte, fibrin, and bacteria. When this white plaque is cleared away, an erythematous area is left behind.
• Erythematous candidiasis is also known as antibiotic irritated mouth. It occurs as a sequel to the use of broad-spectrum antibiotics or corticosteroids.
• Tongue lesions manifest as persistently painful erythematous areas accompanied by central papillary atrophy. It is also known as a kissing lesion when the palate is affected and erythema results from tongue contact.
• Chronic hyperplastic candidiasis, also known as candidal leukoplakia, is characterised by white lesions on the lips, tongue, and buccal mucosa that are firm and persistent.
• These lesions can be either homogenous or nodular, and they can persist for years. It has precancerous characteristics.
• Candida associated lesions include denture stomatitis, angular cheilitis, and median rhomboid glossitis. It is also possible to develop secondary oral candidiasis, such as chronic mucocutaneous candidiasis, chronic familial candidiasis, chronic localised mucocutaneous candidiasis, chronic diffuse mucocutaneous candidiasis, and candidiasis endocrinopathy syndrome.
• Vaginal candidiasis manifests with genital itching, burning, and a white “cottage cheese-like” discharge from the vagina.
• The penis is less commonly affected by a yeast infection and may present with an itchy rash. Rarely, yeast infections can become invasive and travel to other parts of the body, causing fevers and other symptoms.
• buccal candidiasis is one of the most common fungal infections, affecting the buccal mucosa. Candida albicans is responsible for these lesions.
• Candida albicans are among the components of normal oral microflora, and around 30% to 50% of individuals carry this organism. The rate of carriage increases with the age of the patient. Candida albicans is recovered from the jaws of sixty percent of dentate patients.
• There are many forms of Candida species, which present in the buccal cavity. Species of oral Candida include C. albicans, C. glabrata, C. krusei, C. parapsilosis, C. pseudotropicalis, C. stellatoidea, and C. tropicalis. Oral candidiasis can manifest in a diversity of forms in both healthy and immunocompromised hosts.
• These include hyperplastic or atrophic (denture) candidiasis, pseudomembranous candidiasis (thrush), linear gingival erythema, median rhomboid glossitis, and angular cheilitis.
• It can cause a wide spectrum of clinical manifestations, from mild acute superficial infections to fatal disseminated disease. Nearly all cases of disseminated candidiasis are caused by acquired or inherited immunodeficiencies. Candida superficialis is the most prevalent form.

Causative agent of Candidiasis

Candidiasis is a fungal infection caused by Candida, a type of yeast that is part of the normal microflora of the human body. Here are some details about Candidiasis and its causative agent:

• Candida is a eukaryotic organism found in the form of yeasts, molds, or dimorphic fungi.
• Candida albicans is the most common species of Candida that causes Candidiasis, but other species can also be involved.
• Candidiasis occurs when there is an overgrowth of Candida in the body, which can happen when the immune system is compromised, when there is an imbalance in the normal microflora, or when the environment is favorable for Candida growth.
• Candida is a common inhabitant of the oral cavity, gastrointestinal tract, vagina, penis, or other parts of the body, but it becomes pathogenic only when it overgrows.
• Candidiasis can affect different parts of the body, including the oral cavity, vagina, penis, skin, nails, and other areas.
• Oral candidiasis, also known as thrush, is one of the most common forms of Candidiasis. It can present as pseudomembranous, erythematous, or chronic hyperplastic candidiasis, depending on the type of lesion.
• Vaginal candidiasis, also known as a yeast infection, is another common form of Candidiasis. It presents with genital itching, burning, and a white “cottage cheese-like” discharge from the vagina.
• Candidiasis can also cause other types of lesions, such as denture stomatitis, angular cheilitis, and median rhomboid glossitis.
• Candida can be found in the mouths of up to 50% of healthy individuals, but the rate of carriage increases with age.
• Candidiasis can range from mild superficial infections to severe disseminated disease, which is almost exclusively seen in people with acquired or inherited immuno-deficiencies.

Transmission of Candida albicans

• Candida albicans is a normal commensal of the human body, and many healthy individuals carry it without any symptoms or disease.
• However, Candida albicans can be transmitted through direct contact with infected individuals, contaminated objects, or from mother to child during childbirth.
• The fungus can also be transmitted through sexual contact, which is a common mode of transmission for vaginal yeast infections.
• People with weakened immune systems or those taking antibiotics, corticosteroids, or chemotherapy drugs are at higher risk of developing candidiasis as these factors can disrupt the natural balance of microorganisms in the body and create conditions that favor the growth of Candida.
• Some other risk factors that can contribute to candidiasis include uncontrolled diabetes, pregnancy, use of oral contraceptives, and wearing tight-fitting or damp clothing.

Pathogenesis and pathology of Candidiasis

Candida albicans is a common fungal agent that can colonize various organ systems in the host. Its colonization is based on the virulence factors it possesses, which enable it to adhere and invade host tissues. Here are some additional points that expand on this topic:

Virulence factors of Candida albicans:

1. Dimorphic nature: Candida albicans can exist as both a mold and/or yeast form. The ability to switch between these forms enables the fungus to adapt to different environments within the host.
2. Adhesins and invasins: Als-3 proteins are present on the surface of Candida albicans, which help it to attach and invade host tissues.
3. Biofilm formation: Candida albicans can form biofilms during adherence, which enables it to survive and thrive on the host.
4. Secretion of enzymes: Candida albicans secretes proteases, phospholipases, and lipases, which allows it to penetrate into host cells and cause damage.

Types of candidiasis

1. Mucosal candidiasis: Candida albicans can affect the mucosal lining of the host, leading to conditions such as oral candidiasis, candidal vulvovaginitis, gastrointestinal candidiasis, and respiratory candidiasis.
2. Cutaneous candidiasis: This type of candidiasis affects the skin, skin pores, and nails. Examples include candidal folliculitis, candidid, chronic mucocutaneous candidiasis, congenital cutaneous candidiasis, diaper candidiasis, and candidal onychomycosis.
3. Systemic candidiasis: Candida albicans can also affect deep-seated organs and the bloodstream. Examples of systemic candidiasis include candidemia, a form of fungemia that causes sepsis, invasive candidiasis, and chronic systemic candidiasis (hepatosplenic candidiasis).
4. Antibiotic candidiasis: This type of candidiasis is also known as iatrogenic candidiasis, and it occurs due to the overuse or misuse of antibiotics, which disrupt the balance of microorganisms in the host.

Overall, Candida albicans is a versatile fungal agent that can colonize different organ systems in the host. Its virulence factors enable it to adhere and invade host tissues, leading to various types of candidiasis.

Disease cycle

Fungal colonization on the epithelial lining of the host can have significant impacts on the host’s health. Here are some additional points that expand on this topic:

• Nutrient acquisition: Fungi acquire nutrients from the host’s epithelial lining and its cells, providing a suitable platform for growth. This can result in the formation of biofilms, which are communities of microorganisms that attach to a surface and secrete extracellular polymeric substances.
• Superficial infection: Fungi can cause superficial infections by degrading the surface proteins of the epithelial lining. This can lead to symptoms such as itching, redness, and flaking of the skin or mucous membranes. If left untreated, the infection can persist and penetrate into the underlying tissues.
• Tissue invasion: Fungi can invade the tissues and affect the vascular system. This can occur through the spread of the fungus into the bloodstream, which can result in sepsis. The fungus can also escape immune interventions, leading to further tissue damage.
• Disseminated disease: When the fungus invades the endothelial tissues of various organs, it can cause disseminated disease. This can result in symptoms such as fever, chills, and organ dysfunction. Disseminated fungal infections can be life-threatening, especially in immunocompromised individuals.
• Risk factors: Several factors can increase the risk of fungal colonization and infection, including immunosuppression, diabetes, prolonged antibiotic use, and invasive medical procedures.
• Treatment: Treatment for fungal infections typically involves antifungal medications. Depending on the severity and location of the infection, these medications can be administered orally or intravenously. In some cases, surgical intervention may also be necessary.

Clinical Manifestations of Candidiasis

Candidiasis can present with various clinical manifestations depending on the site of infection and the immune status of the host. Here are some of the common clinical manifestations of candidiasis:

• Oral thrush: This is the most common clinical manifestation of candidiasis, especially in immunocompromised individuals. It is characterized by white or yellowish patches on the tongue, inner cheeks, and roof of the mouth. The patches may be painful and bleed when scraped. Other symptoms include a cotton-like feeling in the mouth, difficulty in swallowing, and loss of taste.
• Vulvovaginal candidiasis: This is a common infection that affects women of all ages. It is characterized by itching, burning, and soreness of the vagina and vulva. The discharge is usually white and thick, resembling cottage cheese. The symptoms are more severe before and after menstruation.
• Intertrigo: This is a type of candidiasis that affects skin folds, such as the armpits, groin, and under the breasts. It is characterized by red, itchy, and sore skin that may become scaly or weepy. Intertrigo is more common in obese and diabetic individuals.
• Balanitis: This is a type of candidiasis that affects the head of the penis in males. It is characterized by redness, itching, and soreness of the penis. The foreskin may also become inflamed and difficult to retract. Balanitis is more common in uncircumcised males and those with poor genital hygiene.
• Onychomycosis: This is a type of candidiasis that affects the nails of the fingers and toes. It is characterized by thick, discolored, and brittle nails that may separate from the nail bed. Onychomycosis is more common in individuals with diabetes, poor circulation, and immunodeficiency.
• Invasive candidiasis: This is a serious type of candidiasis that affects the bloodstream, internal organs, and tissues. It can occur in individuals with weakened immune systems, such as cancer patients, transplant recipients, and those on long-term antibiotic therapy. The symptoms of invasive candidiasis include fever, chills, low blood pressure, and organ failure.

Laboratory Diagnosis of Candidiasis

Laboratory diagnosis of candidiasis involves the isolation and identification of Candida species from clinical specimens. The following are some common laboratory techniques used to diagnose candidiasis:

• Microscopy: Microscopic examination of clinical specimens such as vaginal secretions, skin scrapings, and oral swabs can be done to identify the presence of Candida species. Potassium hydroxide (KOH) wet mount or Gram stain is commonly used to visualize yeast cells and pseudohyphae.
• Culture: Fungal culture is the gold standard for diagnosis of candidiasis. Clinical specimens such as blood, urine, sputum, vaginal swabs, and skin scrapings are inoculated on culture media such as Sabouraud agar or CHROMagar Candida. The culture is incubated for 24-48 hours at 37°C, and the presence of Candida species is confirmed by colony morphology, color, and microscopic examination.
• Serology: Serological tests such as enzyme-linked immunosorbent assay (ELISA) can be used to detect the presence of Candida-specific antibodies in serum. However, these tests are not specific to candidiasis as cross-reactivity with other fungal infections can occur.
• Molecular methods: Polymerase chain reaction (PCR) and DNA sequencing can be used to detect Candida species directly from clinical specimens. These techniques have high sensitivity and specificity, but they are not widely available in all clinical laboratories.
• Antifungal susceptibility testing: Antifungal susceptibility testing can be performed on Candida isolates to determine the most effective antifungal drug for treatment. The agar-based or broth-based methods are used to determine the minimum inhibitory concentration (MIC) of antifungal agents against the Candida species.

Treatment of Candidiasis

The treatment of candidiasis depends on the site and severity of the infection, the patient’s age and health status, and the causative species of Candida. The treatment options include:

• Antifungal Medications: Antifungal medications are the mainstay of candidiasis treatment. They can be administered orally, topically, or intravenously, depending on the severity of the infection. Common antifungal medications used to treat candidiasis include fluconazole, itraconazole, voriconazole, caspofungin, micafungin, and amphotericin B.
• Topical Medications: Topical antifungal medications can be used to treat localized candidiasis infections such as oral thrush, vaginal candidiasis, and skin infections. Examples of topical antifungal medications include clotrimazole, miconazole, nystatin, and terbinafine.
• Removal of predisposing factors: Treatment of underlying risk factors, such as diabetes, HIV, and immunosuppression, can help prevent the recurrence of candidiasis.
• Probiotics: Probiotics are beneficial microorganisms that can help restore the natural microbial balance in the body, which can help prevent the growth of Candida. Probiotics can be taken orally or used as vaginal suppositories.
• Lifestyle modifications: Modifying one’s lifestyle can help prevent the recurrence of candidiasis. This includes avoiding tight-fitting clothes, keeping the affected areas dry and clean, and avoiding irritants such as scented products.

Prevention and control

Prevention and control of candidiasis involve various measures aimed at reducing the risk of acquiring or transmitting the disease. Here are some of the prevention and control measures for candidiasis:

• Personal hygiene: Practicing good hygiene measures such as regular bathing, proper handwashing, and avoiding sharing personal items such as towels and clothes can help reduce the risk of candidiasis.
• Managing underlying medical conditions: People with underlying medical conditions such as diabetes, HIV/AIDS, and cancer should manage their conditions well to reduce the risk of candidiasis.
• Avoiding unnecessary use of antibiotics: The unnecessary use of antibiotics can disrupt the normal balance of microorganisms in the body, including Candida, leading to candidiasis. Therefore, avoiding unnecessary use of antibiotics can help prevent candidiasis.
• Avoiding tight-fitting clothing: Wearing loose-fitting clothing, especially in areas such as the groin and underarms, can help reduce moisture and promote air circulation, reducing the risk of candidiasis.
• Proper management of candidiasis in pregnancy: Pregnant women with candidiasis should seek proper medical management to reduce the risk of transmitting the infection to the newborn.
• Prophylactic treatment: People at high risk of candidiasis, such as immunocompromised patients, may receive prophylactic antifungal treatment to prevent the development of the disease.
• Proper use of antifungal medication: When prescribed antifungal medication, it is essential to follow the dosage and duration of treatment as prescribed by the healthcare provider to prevent the development of resistance and recurrence of the disease.
• Proper management of hospital-acquired candidiasis: Hospitals and healthcare facilities can implement infection prevention and control measures, such as proper hand hygiene, environmental cleaning, and the use of personal protective equipment, to reduce the risk of hospital-acquired candidiasis.

FAQ

References

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