Candida (fungus)

For other uses, see Candida.
Candida
Candida albicans at 200X magnification
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Class: Saccharomycetes
Order: Saccharomycetales
Family: Saccharomycetaceae
Genus: Candida
Berkh. (1923)
Type species
Candida vulgaris
Berkh. (1923)

Candida is a genus of yeasts and is the most common cause of fungal infections worldwide.[1] Many species are harmless commensals or endosymbionts of hosts including humans; however, when mucosal barriers are disrupted or the immune system is compromised they can invade and cause disease.[2] Candida albicans is the most commonly isolated species, and can cause infections (candidiasis or thrush) in humans and other animals. In winemaking, some species of Candida can potentially spoil wines.[3]

Many species are found in gut flora, including C. albicans in mammalian hosts, whereas others live as endosymbionts in insect hosts.[4][5][6]

Systemic infections of the bloodstream and major organs (candidemia or invasive candidiasis), particularly in immunocompromised patients, affect over 90,000 people a year in the U.S.[7]

The DNA of several Candida species has been sequenced.[7]

Antibiotics promote yeast infections, including gastrointestinal Candida overgrowth, and penetration of the GI mucosa.[8] While women are more susceptible to genital yeast infections, men can also be infected. Certain factors, such as prolonged antibiotic use, increase the risk for both men and women. People with diabetes or impaired immune systems, such as those with HIV, are more susceptible to yeast infections.[9][10]

Candida antarctica is a source of industrially important lipases.

Biology

When grown in a laboratory, Candida appears as large, round, white or cream (albicans means "whitish" in Latin) colonies, which emit a yeasty odor on agar plates at room temperature.[11] C. albicans ferments glucose and maltose to acid and gas, sucrose to acid, and does not ferment lactose, which help to distinguish it from other Candida species.[12]

Many species of Candida use a non-standard genetic code in the translation of their nuclear genes into the amino acid sequences of polypeptides.[13] The difference in the genetic code between species possessing the alternative code is that the codon CUG (normally encoding the amino acid leucine) is translated by the yeast as a different amino acid, serine. The alternative translation of the CUG codon in these species is due to a novel nucleic acid sequence in the serine-tRNA (ser-tRNACAG), which has a guanosine located at position 33, 5' to the anticodon. In all other tRNAs, this position is normally is occupied by a pyrimidine (often uridine). This genetic code change is the only such known alteration in cytoplasmic mRNA, in both the prokaryotes, and the eukaryotes, involving the reassignment of a sense codon.[14] This novel genetic code may be a mechanism for more rapid adaptation to the organism's environment, as well as playing an important role in the evolution of the genus Candida by creating genetic barriers that encouraged speciation[14][15]

Pathogen

Main article: Candidiasis

Candida are almost universal in low numbers on healthy adult skin[12] and C. albicans is part of the normal flora of the mucous membranes of the respiratory, gastrointestinal and female genital tracts. The dryness of skin compared to other tissues prevents the growth of the fungus, but damaged skin or skin in intertriginous regions is more amenable to rapid growth.[16]

Overgrowth of several species including C. albicans can cause superficial infections such as oropharyngeal candidiasis (thrush) and vulvovaginal candidiasis (vaginal candidiasis). Oral candidiasis is common in elderly denture wearers.[17] In otherwise healthy individuals, these infections can be cured with topical or systemic antifungal medications [18] (commonly over-the-counter antifungal treatments like miconazole or clotrimazole). In debilitated or immunocompromised patients, or if introduced intravenously, candidiasis may become a systemic disease producing abscess, thrombophlebitis, endocarditis, or infections of the eyes or other organs.[7][12] Typically, relatively severe neutropenia is a prerequisite for Candida to pass through the defenses of the skin and cause disease in deeper tissues; in such cases, mechanical disruption of the infected skin sites is typically a factor in the fungal invasion of the deeper tissues.[16]

Applications

C. albicans has been used in combination with carbon nanotubes (CNT) to produce stable electrically conductive bio-nano-composite tissue materials that have been used as temperature sensing elements.[19]

Species

Among Candida species, C. albicans, which is a normal constituent of the human flora, a commensal of the skin and the gastrointestinal and genitourinary tracts, is responsible for the majority of Candida bloodstream infections (candidemia). Yet, there is an increasing incidence of infections caused by C. glabrata and C. rugosa, which could be because they are frequently less susceptible to the currently used azole antifungals.[20] Other medically important species include C. parapsilosis, C. tropicalis and C. dubliniensis.[7]

Other Candida species, such as C. oleophila have been used as biological control agents in fruit.[21]

References

  1. ↑ Manolakaki, D.; Velmahos, G.; Kourkoumpetis, T.; Chang, Y.; Alam, H. B.; De Moya, M. M.; Mylonakis, E. (2010). "Candida infection and colonization among trauma patients". Virulence. 1 (5): 367–375. doi:10.4161/viru.1.5.12796.
  2. ↑ Kourkoumpetis, Themistoklis K., et al. "The effect of cumulative length of hospital stay on the antifungal resistance of Candida strains isolated from critically ill surgical patients." Mycopathologia 171.2 (2011): 85-91.
  3. ↑ K. Fugelsang, C. Edwards Wine Microbiology Second Edition, pp. 3–28 Springer Science and Business Media , New York (2010) ISBN 0387333495
  4. ↑ Spanakis, Elias K., et al. "Statin Therapy and Decreased Incidence of Positive Candida Cultures Among Patients With Type 2 Diabetes Mellitus Undergoing Gastrointestinal Surgery." Mayo Clinic Proceedings. Vol. 85. No. 12. Elsevier, 2010.
  5. ↑ Nguyen NH, Suh SO, Blackwell M (2007). "Five novel Candida species in insect-associated yeast clades isolated from Neuroptera and other insects". Mycologia. 99 (6): 842–858. doi:10.3852/mycologia.99.6.842. PMID 18333508.
  6. ↑ Suh SO, Nguyen NH, Blackwell M (2008). "Yeasts isolated from plant-associated beetles and other insects: seven novel Candida species near Candida albicans". FEMS Yeast Res. 8 (1): 88–102. doi:10.1111/j.1567-1364.2007.00320.x. PMID 17986254.
  7. 1 2 3 4 Enfert C, Hube B (editors) (2007). Candida: Comparative and Functional Genomics. Caister Academic Press. ISBN 978-1-904455-13-4.
  8. ↑ Kennedy, MJ; et al. (1987). "Mechanisms of association of Candida albicans with intestinal mucosa". Med Microbiol. 24: 333–341. doi:10.1099/00222615-24-4-333.
  9. ↑ Steckelberg, James M. (2012-09-18). "Male yeast infection: Can I get it from my girlfriend?". Mayo Clinic. Retrieved 2014-03-23.
  10. ↑ "Yeast Infections: MedlinePlus". Nlm.nih.gov. Retrieved 2014-03-23.
  11. ↑ "Candida species". DoctorFungus.org. Archived from the original on 2007-02-08. Retrieved 2007-02-09.
  12. 1 2 3 Edward Adelberg; Joseph Melnick; Ernest Jawetz (1978). Review of Medical Pharmacology. Lange Medical Publications.
  13. ↑ "CGD Help: Non-standard Genetic Codes". Candida Genome Database. Retrieved 1 May 2015.
  14. 1 2 Santos, MA; Ueda, T; Watanabe, K; Tuite, MF (November 1997). "The non-standard genetic code of Candida spp.: an evolving genetic code or a novel mechanism for adaptation?". Molecular Microbiology. 26 (3): 423–31. doi:10.1046/j.1365-2958.1997.5891961.x. PMID 9402014.
  15. ↑ Silva, Raquel M; Paredes, João A; Moura, Gabriela R; Manadas, Bruno; Lima-Costa, Tatiana; Rocha, Rita; Miranda, Isabel; Gomes, Ana C; Koerkamp, Marian J G; Perrot, Michel; Holstege, Frank C P; Boucherie, Hélian; Santos, Manuel A S (11 October 2007). "Critical roles for a genetic code alteration in the evolution of the genus Candida". The EMBO Journal. 26 (21): 4555–4565. doi:10.1038/sj.emboj.7601876. PMC 2063480Freely accessible. PMID 17932489. Retrieved 1 May 2015.
  16. 1 2 Goehring, Richard V. (2008). Mims' medical microbiology. (4th ed.). Philadelphia, PA: Mosby Elsevier. p. 656. ISBN 9780323044752.
  17. ↑ Darwazeh A, Lamey P, Samaranayake L, MacFarlane T, Fisher B, Macrury S, MacCuish A (1990). "The relationship between colonisation, secretor status and in-vitro adhesion of Candida albicans to buccal epithelial cells from diabetics". J Med Microbiol. 33 (1): 43–9. doi:10.1099/00222615-33-1-43. PMID 2231671.
  18. ↑ "Yeast Infections (Candidiasis) in Men and Women". WebMD. 2012-11-12. Retrieved 2014-03-23.
  19. ↑ Di Giacomo, R (2013-03-07). "Candida albicans/MWCNTs: A Stable Conductive Bio-Nanocomposite and Its Temperature-Sensing Properties". IEEE Transactions on Nanotechnology. 12 (2): 111–114. doi:10.1109/TNANO.2013.2239308. ISSN 1536-125X. Retrieved 2014-03-23.
  20. ↑ "Candida rugosa, an Emerging Fungal Pathogen with Resistance to Azoles: Geographic and Temporal Trends from the ARTEMIS DISK Antifungal Surveillance Program". J Clinical Microbiology. 44: 3578–3582. 2006. doi:10.1128/jcm.00863-06.
  21. ↑ "Efficacy of Candida oleophila strain 128 in preventing Penicillium Expansum infection in apricot fruit". Acta Hort. ISHS. 485: 141–148. 1999.
  22. ↑ James, S. A.; Carvajal Barriga, E. J.; Bond, C. J.; Cross, K.; Núñez, N. C.; Portero, P. B.; Roberts, I. N. (2009). "Candida carvajalissp. Nov., an ascomycetous yeast species from the Ecuadorian Amazon jungle". FEMS Yeast Research. 9 (5): 784–788. doi:10.1111/j.1567-1364.2009.00518.x. PMID 19459983.
  23. ↑ Chang, C. F.; Lin, Y. C.; Chen, S. F.; Carvajal Barriga, E. J.; Barahona, P. P.; James, S. A.; Bond, C. J.; Roberts, I. N.; Lee, C. F. (2012). "Candida theae sp. nov., a new anamorphic beverage-associated member of the Lodderomyces clade". International Journal of Food Microbiology. 153 (1–2): 10–14. doi:10.1016/j.ijfoodmicro.2011.09.012. PMID 22088606.

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