Candida albicans

Biology

Habitat and transmission: C. albicans is a commensal organism that resides on the skin and muco-cutaneous sites in all humans. It commonly colonises areas such as the gastro intestinal (GI) tract and the reproductive tracts in men and women. Most infections are thought to be caused by the endogenous C. albicans microflora, although exogenous C. albicans can be transmitted from the hands of healthcare workers or contaminated medical devices. C. albicans can also form biofilms which aid attachment to medical apparatus and in-dwelling devices such as catheters (Achkar and Fries, 2010).

Treatment and antimycotic resistance: Mild cases of candidiasis can be treated with “over-the-counter” thrush medications containing an antimycotic agent called clotrimazole, which can be either a topical or oral treatment regime (Achkar and Fries, 2010). In most cases of thrush or oral candidiasis a single or short treatment is sufficient to clear the infection. In more serious infections other antimycotic triazole agents such as fluconazole can be used to treat infections. There has been a recent increase in the involvement of non-C. abicans species in candidiasis (Achkar and Fries, 2010). This is a particularly worrying trend as other Candida species often have resistance to triazole treatments (Achkar and Fries, 2010). The reasons for this shift are not fully understood.

Prevention and control: As most infections are endogenous in nature it is very difficult to prevent infections occurring. Some have suggested the use of patient decolonisation using antimycotic drugs, however there is concern that this could cause an increase in the drug resistance of endogenous microorganisms (Pfaller, 1996). However, exogenous transmission can be reduced by frequent hand-hygiene, use of contact precautions, wearing gloves when inserting medical devices, frequent changing of cannulae and catheters to minimise build-up of Candida species in biofilms and thorough environmental decontamination.

Symptoms/Effects

Disease and symptoms: Candidiasis is a common cause of infection of the skin, oral cavity, oesophagus, GI tract, vagina, genitourinary tract and vascular system (Calderone and Fonzi, 2001). Infections range from mild thrush and denture-related infections to life-threatening systemic infections. Most infections are endogenous in origin and arise from a disturbance of the microflora or from recent use of antibiotics (Achkar and Fries, 2010). Most women will have a C. albicans infection in their life-time. These infections are generally short-lived; however a small percentage will have recurrent candidiasis. Candidasis is also a very important cause of morbidity and mortality in severely immunocompromised patients such as AIDS patients and cancer patients receiving chemotherapy(Calderone and Fonzi, 2001).

Technical

References:

Achkar J.M. and Fries B.C. (2010) Candida infections of the genitourinary tract. Clin Microbiol Revs. 23(2): 253-273.

Calderone R.A. and Fonzi W.A. (2001) Virulence factors of Candida albicans. Trends Microbiol. 9(7): 327-335.

Pfaller M.A. (1996) Nosocomial Candidiasis: emerging species, reservoirs, and modes of transmission. Clin Infect Dis. 22(Suppl 2): S89-S94.