Candidiasis

Definition

Candidiasis is an infection caused by a species of the yeast Candida, usually Candida albicans. This is a common cause of vaginal infections in women. Also, Candida may cause mouth infections in people with reduced immune function, or in patients taking certain antibiotics. Candida can be found in virtually all normal people but causes problems in only a fraction. In recent years, however, several serious categories of candidiasis have become more common, due to overuse of antibiotics, the rise of AIDS, the increase in organ transplantations, and the use of invasive devices (catheters, artificial joints, and valves)-all of which increase a patient's susceptibility to infection.



(Fig 3.1a; Fig 3.1b.)
This patient's tongue is infected with candidiasis. A transmission electron microscopy (TEM) of Candida albicans.

Demographics

The candida organism is present in the oropharyngeal areas in 30 to 55% of healthy young adults. About 75% of women are infected with vaginal candidiasis at least one time in their lifetime. The candida species is now the fourth most commonly isolated organism from blood cultures and is the most common cause of fungal infection in patients whose immune systems are compromised.

Risk factors

Patients at high risk for the development of candidiasis include patients who are often extremely ill. Patients in neonatal, pediatric, and adult intensive care units are considered to be at high risk. Other high risk patients are patients who are immunosuppressed due to chemotherapy, radiation therapy, severe trauma, and organ transplantation. Patients undergoing procedures such as recent surgery, hemodialysis, urinary catheterization, central venous access device placement, and those on mechanical ventilation for longer than 3 days are at high risk for the development of invasive or systemic candidiasis.

Neonates and older adults over the age of 65 years are at highest risk for infection with the candida organism.



Vaginal candidiasis

Over one million women in the United States develop vaginal yeast infections each year. It is not life-threatening, but it can be uncomfortable and frustrating.

Oral candidiasis

This disorder, also known as thrush, causes white, curd-like patches in the mouth or throat.

Deep organ candidiasis

Also known as invasive candidiasis, deep organ candidiasis is a serious systemic infection that can affect the esophagus, heart, blood, liver, spleen, kidneys, eyes, and skin. Like vaginal and oral candidiasis, it is an opportunistic disease that strikes when a person's resistance is lowered, often due to another illness. There are many diagnostic categories of deep organ candidiasis, depending on the tissues involved.

Vaginal candidiasis

Most women with vaginal candidiasis experience severe vaginal itching. They also have a discharge that often looks like cottage cheese and has a sweet or breadlike odor. The vulva and vagina can be red, swollen, and painful. Sexual intercourse can also be painful.

Oral candidiasis

Whitish patches can appear on the tongue, inside of the cheeks, or the palate. Oral candidiasis typically occurs in people with abnormal immune systems. These can include people undergoing chemotherapy for cancer, people taking immunosuppressive drugs to protect transplanted organs, or people with HIV infection.

Deep organ candidiasis

Anything that weakens the body's natural barrier against colonizing organisms-including stomach surgery, burns, nasogastric tubes, and catheters-can predispose a person for deep organ candidiasis. Rising numbers of AIDS patients, organ transplant recipients, and other individuals whose immune systems are compromised help account for the dramatic increase in deep organ candidiasis in recent years. Patients with granulocytopenia (deficiency of white blood cells) are particularly at risk for deep organ candidiasis.

Diagnosis

Often clinical appearance gives a strong suggestion about the diagnosis. Generally, a clinician will take a sample of the vaginal discharge or swab an area of oral plaque, and then inspect this material under a microscope. Under the microscope, it is possible to see characteristic forms of yeasts at various stages in the lifecycle.

Fungal blood cultures should be taken for patients suspected of having deep organ candidiasis. However, blood cultures may not detect up to 50% of cases of disseminated candidiasis. A more specific test to detect Beta-glucan, a fungal cell wall component, is the serum Beta-D-glucan detection assay. This test has shown to be highly specific in detecting fungal infections.

A tissue biopsy of suspected infected areas may also be helpful in confirming a diagnosis of systemic or disseminated candidiasis.

Vaginal candidiasis

In most cases, vaginal candidiasis can be treated successfully with a variety of over-the-counter antifungal creams or suppositories. These includeMonistat, Gyne-Lotrimin, and Mycelex. However, infections often recur. However, a single 150 mg dose of oral fluconazole (Diflucan) has been shown to as effective or better than topical antifungal agents when treating acute cases of vaginal candidiasis.

Oral candidiasis

This is usually treated with prescription lozenges or mouthwashes. Some of the most-used prescriptions are nystatin mouthwashes (Nilstat or Nitrostat) and clotrimazole lozenges. Other treatment options include amphotericin B oral suspension or treatment with systemic azole medications such as fluconazole (Diflucan), itraconazole (Sporonox), or posaconazole (Noxafil) for more severe oral infections.

Deep organ candidiasis

Guidelines for the treatment of invasive candidiasis were revised in 2009 by the Infectious Diseases Society of America (ISDA). The guidelines include the recommended use of drugs such as caspofungin (Cancidas), micafungin (Mycamine), and anidulafungin (Eraxis), which are classified as echinocandins, and the drugs voriconazole (Vfend) and posaconazole (Noxafil), which are classified as triazoles. Lipid formulations of amphotericin B are also recommended in the treatment of systemic fungal infections caused by candida organisms. Treatment with fluconazole (Diflucan) continues to be recommended as first line treatment for invasive candidiasis in non-neutropenic patients.

Alternative treatment

Home remedies for vaginal candidiasis include vinegar douches or insertion of a paste made from Lactobacillus acidophilus powder into the vagina. In theory, these remedies will make the vagina more acidic and therefore less hospitable to the growth of Candida. Fresh garlic (Allium sativum) is believed to have antifungal action, so incorporating it into the diet or inserting a gauze-wrapped, peeled garlic clove into the vagina may be helpful. The insert should be changed twice daily. Some women report success with these remedies; they should try a conventional treatment if an alternative remedy isn't effective.

Vaginal candidiasis

Althoughmost cases of vaginal candidiasis are cured reliably, these infections can recur. To limit recurrences, women may need to take a prescription anti-fungal drug or take other anti-fungal drugs on a preventive basis.

Oral candidiasis

These infections can also recur, sometimes because the infecting Candida develops resistance to one drug. Therefore, a physician may need to prescribe a different drug.

Deep organ candidiasis

The prognosis depends on the category of disease as well as on the condition of the patient when the infection strikes. Patients who are already suffering from a serious underlying disease are more susceptible to deep organ candidiasis that spreads throughout the body.

Mortality rates for disseminated candidiasis have not improved significantly over the years. It is estimated that as many as 30 to 40% of patients diagnosed with severe cases of systemic candidiasis will die from infection with this pathogen.

Prevention

Because Candida is part of the normal group of microorganisms that co-exist with all people, it is impossible to avoid contact with it. Good vaginal hygiene and good oral hygiene might reduce problems, but they are not guarantees against candidiasis.

Because hospital-acquired (nosocomial) deep organ candidiasis is on the rise, people need to be made aware of it. Patients should be sure that catheters and other medical devices are properly maintained and used for the shortest possible time lengths.