Candida albicans infection

Candida is a conditionally-pathogenic fungus. It is all around us, normally found on skin, in the mouth, gut, and other mucus membranes. It causes infection when antibiotics or other factors reduce our natural resistance to it's overgrowth. Most candida infections are superficial, limited to mucus membranes¹.

Disseminated infection by Candida of internal organs can occur in severely immunocompromised patients, such as those with cancer, serious burns, or AIDS. This is a much more serious condition than superficial Candida infection. Disseminated Candida infection is usually determined by the presence of candida in the blood, and is potentially life-threatening. It should not be confused with superficial candida infections, which are not life-threatening. The two classes of infection are similar in that some of the same antifungal drugs may be used, and both can be difficult to eradicate.

The most common origin of Candida infection is the overgrowth of one's own yeast flora, the Candida yeast cells that live on our skin and in our GI tract. If the diverse population of microorganisms that normally reside in these places is reduced, Candida overgrowth and superficial infection can occur. Some examples are listed below.

• Skin rashes can occur due to chronic exposure to detergent or frequent washing that eliminates the normal microflora on the skin(washer-woman's rash).
• Candida vaginitis can occur as a side effect of antibiotic use, which reduces the normal protective microflora of the vagina.
• Antibiotics can lead to increased numbers of candida in the GI tract, and predispose immunocompromised patients to disseminated candida infection².

The gastrointestinal microflora

The normal bacterial population of the gastrointestinal tract is referred to as the "GI microflora". While bacteria are usually viewed as contaminants or agents of disease, this population of bacteria has a symbiotic relationship with man. It is essential for GI health and resistance to infection.

Animals raised experimentally in a sterile environment, and therefore with a sterile GI tract, experience serious gastrointestinal dysfunction. This appears to be due to their lack of a GI microflora. Bacteria have been a part of the environment during evolution, and it's therefore possible for "normal" health to depend upon it's presence. The GI microflora is believed to prevent the proliferation of other, less desirable microorganisms, and play a role in immune regulation and vitamin synthesis. The microflora protects against infection by the following mechanisms:

• Physically crowding out potential pathogens by creating a barrier over the surface of the mucosa⁴.
• Stimulating our immune system to respond effectively to some infections.
• Competitive inhibition by taking all available food sources for themselves.
• Maintaining a low pH which inhibits the growth of some other microorganisms.

Antibiotics

The advent of antibiotics had the unintended consequence of reducing the human GI microflora for the first time in history. This caused GI side effects, from simple diarrhea to protracted infection by resistant microorganisms (such as Clostridium difficile).

Antibiotic therapy temporarily suppresses the numbers of the GI microflora. It generally returns to it's previous status, but some species might be lost permanently³. The significance of this is not yet known.

Antibiotics temporarily increase the levels of candida in the GI tract. In immunocompromised patients, this increases the risk of systemic candida infection². In research with mice, antibiotic treatment caused commensual candida yeasts to colonize and deeply penetrate the the mucosa of the small intestine⁴. Similar research on humans hasn't been done. The practice of prescribing tetracycline long-term for facial acne has an unknown effect on the GI microflora. This is a suggested risk factors for Candida-Related Complex(CRC).

Candida research links

• Candida albicans information, notes for C. albicans investigators from the University of Minnesota

References

1. Odds FC "Candida and Candidosis" second edition, Bailliere Tindall, 1988
2. Samonis G. et al. "Prospective study of the impact of broad-spectrum antibiotics on the yeast flora of the human gut" European Journal of Clinical Microbiology and Infectious Disease 13:665-667, 1994
3. Mangin I. et al. "Identification of Bifidobacteria strains by rRNA gene restriction patterns" Applied and Environmental Microbiology 60(5):1451-1458, May 1994
4. Kennedy MJ et al. "Ecology of Candida albicans gut colonization: inhibition of Candida adhesion, colonization, and dissemination from the gastrointestinal tract by bacterial antagonism." Infection and Immunity 49(3):654-663, Sept. 1985

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