Candidiasis
The Candida fungus is both normal flora and an invasive pathogen. The range of infection with Candida species varies from a benign local mucosal membrane infection to disseminated disease. Severe disease is typically associated with an immunocompromised state including those vulnerable to iatrogenic pathogens in the intensive care unit or those with predisposing immunologic conditions such as malignancy, organ dysfunction, or immunosuppressive therapy. 1
The increased prevalence of local and systemic disease caused by Candida species has resulted in numerous new clinical syndromes, the expression of which is primarily dependent on the immune status of the host. Candida species produce a wide spectrum of diseases, ranging from superficial mucocutaneous disease to invasive illnesses, such as hepatosplenic candidiasis, Candida peritonitis, and systemic candidiasis. Management of serious and life-threatening invasive candidiasis remains severely hampered by delays in diagnosis and the lack of reliable diagnostic methods that allow detection of both fungemia and tissue invasion by Candida species. 2
Oral candidiasis is most commonly associated with Candida albicans, although other species, such as C. glabrata and C. tropicalis, are frequently part of the normal oral flora. A number of factors predispose patients to develop candidiasis: infancy, old age, antibiotic therapy, steroid and other immunosuppressive drugs, xerostomia, anemia, endocrine disorders, and primary and acquired immunodeficiency. Candidiasis is a common finding in people with HIV infection. Reports describe oral candidiasis during the acute stage of HIV infection,(10) but it occurs most commonly with falling CD4+ T-cell count in middle and late stages of HIV disease. 4
Invasive candidiasis is not a disease seen in normal healthy hosts. Rather, there are a large number of reasonably well characterized risk factors for this group of diseases (see table, below). Some of the risk factors are other diseases (e.g., renal failure & hemodialysis), while others are induced by various therapies (e.g., chemotherapy or gut-related surgery). Despite the association of burn units with relatively high rates of invasive candidiasis [772], this association is otherwise little documented [1305]. 6
Oropharyngeal and vulvovaginal disease are the most common forms of mucocutaneous candidiasis. Up to 90% of persons with advanced untreated HIV infection develop OPC, with 60% having at least 1 episode per year with frequent recurrences (50-60%).(16,21,24-32) Esophageal candidiasis occurs less frequently (10-20%) but is the leading cause of esophageal disease.(33-35) Vaginal candidiasis has been noted in 27-60% of women, similar to the rates of oropharyngeal disease.(36-38) However, the incidence appears to be similar in HIV-infected and HIV-uninfected women.(8) Of note, 75% of all women of childbearing age develop vaginal candidiasis and 40% will have a second occurrence. Few women (<5%) experience frequent recurrences (defined as >=4 infections in a 12-month period). 5
Candida species also contain their own set of well-recognized virulence factors. Although not well characterized, several virulence factors may contribute to their ability to cause infection. The main virulence factors are surface molecules that permit adherence of the organism to other structures (eg, human cells, extracellular matrix, prosthetic devices), acid proteases, and the ability to convert to a hyphal form. 2
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 speads throughout the body. 20
Non-albicans Candida accounted for 70% of candidemia in a Northern Indian pediatric intensive care unit. Candida species isolated were Candida tropicalis (48.4%), C albicans (29.7%), C guilliermondii (14.1%), C krusei (6.3%), and C glabrata (1.6%). 1
Symptoms of OPC may include burning pain, altered taste sensation, and difficulty swallowing liquids and solids. Many patients are asymptomatic. Most persons with OPC present with pseudomembranous candidiasis or thrush (white plaques on the buccal mucosa, gums, or tongue) and less commonly with acute atrophic candidiasis (erythematous mucosa) or chronic hyperplastic candidiasis (leukoplakia, distinct from "hairy leukoplakia"; see chapter on Oral Manifestations) involving the tongue, or angular cheilitis (inflammation and cracking at the corners of the mouth). 5
Esophageal candidiasis usually is accompanied by the presence of OPC. Typically, dysphagia and odynophagia are described. In as many as 40% of patients with OPC, esophageal involvement may be asymptomatic.(6) Occasionally, esophageal disease may occur in the absence of clinically detectable oropharyngeal disease. 5
Candida species are the most common cause of fungal infection affecting immunocompromised patients. Oropharyngeal colonization is found in 30-55% of healthy young adults, and Candida species may be detected in 40-65% of normal fecal florae. 2
Potassium hydroxide (KOH) preparation of a smear collected by gentle scraping of the affected area with a wooden tongue depressor. Visible hyphae or blastospheres on KOH mount indicate Candida infection. 18
Candida species are the most common cause of fungal infections. Candida species produce infections that range from non?life-threatening mucocutaneous illnesses to invasive processes that may involve virtually any organ. Such a broad range of infections requires an equally broad range of diagnostic and therapeutic strategies. These guidelines summarize current knowledge about treatment of multiple forms of candidiasis for the Infectious Diseases Society of America (IDSA). This document covers the following 4 major topical areas. 8
The role of the microbiology laboratory: To a greater extent than for other fungi, treatment of candidiasis can now be guided by in vitro susceptibility testing. However, susceptibility testing of fungi is not considered a routine testing procedure in many laboratories, is not always promptly available, and is not universally considered as the standard of care. Knowledge of the infecting species, however, is highly predictive of likely susceptibility and can be used as a guide to therapy. The guidelines review the available information supporting current testing procedures and interpretive breakpoints and place these data into clinical context. Susceptibility testing is most helpful in dealing with deep infection due to non?albicans species of Candida. In this setting, especially if the patient has been treated previously with an azole antifungal agent, the possibility of microbiological resistance must be considered. 8
Erythematous candidiasis should be differentiated from other red lesions, such as Kaposi’s sarcoma or erythroplakia. Histologically, oral candidiasis contains Candida hyphae in the superficial epithelium when viewed under a PAS stain. The inflammatory responses often associated with Candida infection may be absent in immunocompromised patients. The creamy white plaques of pseudomembranous candidiasis are removable; the white lesions of hairy leukoplakia are nonremovable. 4
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