Download Candida Albicans— An Opportunistic Organism

Candida Albicans—
An Opportunistic Organism
By Max Sherman
The opportunistic fungal pathogen, Candida albicans, lives benignly in our bodies, on our
skin and mucosa membranes, until it senses we are weak; then it quickly adapts and
goes on the offensive. One of the diseases caused by this pathogen, vulvovaginal candidiasis, is commonplace and may affect up to 75% of women at least once in their lifetime.
The fungus causes other diseases as well, including a sometimes fatal infection known as
candidemia, in compromised patients.
Unfortunately, reports of human infections with environmental (airborne) fungi are
on the increase throughout the world. More importantly, fungal infections are becoming
more resistant to current drugs.1 There have been recent reports that new dimorphic
emmonsia species are infecting patients with advanced human immunodeficiency virus
(HIV).2 Dimorphic organisms have the ability to switch between a yeast-like form and a filamentous form. In pathogenic fungi like C. albicans, this capacity has been correlated with
virulence. This article describes the history of its discovery, characteristics, forms, opportunism, fungal infections and resistance.
Discovery
David Gruby, a Hungarian physician, generally is recognized as the discoverer of various
fungi that produce diseases. He built an excellent microscope in the early 1840s and
began a study of the pathology of body fluids. His attempt at microscopic differentiation of
pus from other pathological substances, such as mucus or sputum, was a careful, original
investigation in a new field of medicine. In 1841, Gruby found a fungus in favus, a contagious skin disease situated in hair follicles, and shortly thereafter discovered C. albicans
(then called Oidium albicans), the cause of thrush in children.3 His work was recognized in
The New England Journal of Medicine’s 200th anniversary issue.4
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In 1923, Christine Marie Berkhout named Candida albicans for the white robe, toga
candida, worn by Roman senators and senatorial candidates.5 Albicans also comes from
Latin albicare, meaning “to whiten.”
The Organism and its Various Forms
Candida albicans is a yeast that resides in the mouth, throat, intestines and genitourinary
tract of most humans. It usually is considered a normal part of the bowel flora. Of the
Candida species afflicting humans, C. albicans is by far the most common. It is a eukaryote and belongs to the class Ascomycetes and the family Saccharomycetaceae. C. albicans
can live as a harmless commensal organism in many different body locations and is carried by almost half the population. The organism can change cellular morphology and grow
as either ovoid, yeast form cells or as elongated filaments. This growth occurs in response
to a change in the host environment when the yeast converts from a benign inhabitant
into a disease-causing pathogen.
The current view is that this ability to switch between the two forms underpins the
success of C. albicans as a pathogen. Filaments are thought to be important for tissue
invasion, whereas yeast cells are used for dissemination in the host.6
In addition to growth as yeast or filaments, C. albicans can switch to a multicellular
form, growing as a biofilm. Biofilms are multicellular communities of yeast and filamentous
cells surrounded by a coat of extracellular matrix. Biofilms of C. albicans form an attachment to surfaces and are an important issue in clinical settings.7 Biofilms readily form on
implanted medical devices, such as catheters, pacemakers and prosthetic devices, giving the fungus access to the bloodstream for dissemination and causing life-threatening
systemic infections. Maturation of biofilms is accompanied by development of drug resistance. What triggers drug resistance is not completely understood, but it likely is a result
of physical properties of the biofilm and metabolic and gene expression changes.8
Fungal Infections
Infections caused by C. albicans can be defined in two broad categories: superficial mucocutaneous and systematic invasive, which involves the spread of the organism to the
bloodstream (candidemia) and to the major organs. Systemic invasive candidemia often is
fatal. Superficial infections affect the various mucous membranes on body surfaces, such
as in oral and vaginal thrush. (Thrush refers to the resemblance of the white flecks present in some forms of candidiasis with the breast of the bird with the same name.) The
incidence of vulvovaginal candidiasis (vaginal thrush) has increased approximately two-fold
in the last decade9 There are more than 20 species of Candida yeasts that can cause
infections in humans, and, although infections caused by these other species are increasing in prevalence, the majority of candidiasis is still caused by C. albicans.10
C. albicans acts a double agent. In most of us, it lives peacefully as a commensal
microbe, but for people whose immune systems are compromised by HIV or other severe
diseases, it frequently is deadly. Given the opportunity to breach the immune system
defenses, the yeast can cross into the bloodstream and switch from peaceful coexistence
to attack mode, producing long filaments that enter tissues and destroy them.11
C. albicans is the most common species of the Candida fungus and, as mentioned
earlier, the leading cause of vaginal and oral yeast infections. It is the fourth most common hospital-acquired blood-borne pathogen in the US, and is present in the mouths of
30–50% of healthy adults.12 Because of the widespread nature of Candida, the potential
for overgrowth and infection is common in the young, the elderly, immune-compromised
individuals and people receiving corticosteroid or chemotherapy treatments.
There is at least one other yeast to worry about. Researchers in Sweden have discovered that Candida glabrata is becoming more resistant to fungicidal medicine. It
has become the second most-common yeast pathogen in humans. C. glabrata mutates
surprisingly rapidly by reorganizing its chromosomes and making extra copies of large
chromosome pieces. This process enables the yeast to tolerate higher doses of antifungal drugs. C. glabrata, like C. albicans, can be directly life-threatening to people with poor
immune defense when it enters the bloodstream.13
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Final Thoughts
During my research for this article I found a book written by a certified metabolic technician who categorizes C. albicans as the quiet epidemic.14 He claims our society is crawling
with pollutants that enhance Candida and clobber us. As the book notes, our food is
refined, additivized and chemicalized, and then so loaded with sugars and starch that
we feed Candida very happily. The book goes on to recommend a regimen of antifungals,
blood purifiers, intestinal cleansers, digestive aids, immune boosters, probiotics, detoxifiers and oxygen therapy. And I forgot to mention weekly colonic irrigations, which are part
of a rigorous, eight-week treatment program. I am not expert enough to discourage anyone
from trying the program, although it may be better than a once-recommended method of
inhaling the breath of a duck. That treatment was used in an effort to cure children of
thrush and other disorders of the mouth and throat.
About the Author
Max Sherman is head of Sherman Consulting Services in Warsaw, IN. He can be reached at [email protected].
References
1. Sudbery PE. “Growth of Candida albicans hyphae.” Nature Reviews/Microbiology. 2011; 9:737-48.
2. Papon N et al. “Emerging and emerged pathogenic Candida species: beyond the Candida albicans paradigm.” PLOS
Pathogens. 2013; 9 (9):1-4.
3. Gruby D. Encyclopedia.com website. http://www.encyclopedia.com/doc/1G2-2830901758.html. Accessed 7 October 2013.
4. Fauci AS and Morens DM. “The perpetual challenge of infectious diseases.” New Engl J Med. 2012; 366(5):454-61.
5. Holland SM and Vinh DC. “Yeast infections—human genetics on the rise.” New Engl J Med. 2009; 361(18):1798-1801.
6. Op cit 2.
7. Uwamahoro N and Traven A. “Yeast, filaments and biofilms in pathogenesis of Candida albicans.” Australian Biochemist.
2010; 41(1):16-18.
8. Op cit 6.
9. Op cit 2.
10. Sudbery P et al. “The distinct morphogenic states of Candida albicans.” Trends in Microbiology. 2004; 12(7):317-24.
11. “Possible way to turn fungus from foe to friend.” Science Daily. http://sciencedaily.com/
releases/2013/09/130924122458.htm. Accessed 25 September 2013.
12. “New way the body fights fungal infections discovered.” Science Daily. http://www.sciencedaily.com/
releases/2009/06/090611120742.htm. Accessed 25 September 2013.
13. “Yeast infections worsening: rapidly mutating yeast causing more infections.” Science Daily. http://sciencedaily.com/
releases/2009/04/090401204205.htm. Accessed 25 September 2013.
14. Weinberger S. Candida albicans: the quiet epidemic. San Anselmo, CA: Healing Within Products; 2000.
Cite as: Sherman, M. “Candida Albicans–An Opportunistic Organism.” Regulatory Focus. January 2014. Regulatory Affairs
Professionals Society.
© 2014 by the Regulatory Affairs Professionals Society. All rights reserved.
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