Candida albicans

Candida albicans
	Candida albicans , pseudohyphae (left, with blastoconidia and chlamydospores ) and yeast-like cells (right)
Systematics
Subdivision :	Saccharomycotina
Class :	Saccharomycetes
Order :	Real yeast (Saccharomycetales)
	incertae sedis
Genre :	Candida
Type :	Candida albicans
Scientific name
	Candida albicans
	( CPRobin ) Berkhout

Candida albicans (formerly Monilia albicans and Oidium albicans ), the "thrush fungus", is a fungus of the Candida group , which isassigned to yeasts . It is the most common cause of candidiasis (also called candidiasis, candidiasis, candidamycosis, monoliasis, thrush or, in babies, “diaper fungus”). This fungus can often be found on the mucous membranes of the mouth and throat and in the genital area and in the digestive tract in people of equal temperature ("warm-blooded animals"). According to the German Nutrition Society, it can be detected inaround 75% of all healthy people. The fungus can also appear between the fingers and toes, and on the fingernails and toenails.

C. albicans is one of the facultative pathogens (only causing disease under certain conditions) and is to be regarded as a saprobiont that settles in a state of equilibrium with the human immune system and other microorganisms. The colonization by this fungus usually causes hardly any complaints. In the absence of or reduced immunity (in the context of other basic diseases such as diabetes mellitus , cancer, AIDS , or through the administration of certain drugs such as antibiotics), however, the colonization with Candida albicans or related fungi can increase significantly, which then manifests as mycosis . In most cases, these are endogenous infections, i.e. the pathogen was already at the site of the infection before the outbreak of the disease, more rarely exogenous infections, i.e. by pathogens acquired from outside.

Candidiasis can be treated with antimycotics (antifungal agents) that intervene in the synthesis of the fungal cell wall (for example caspofungin ) or the cell membrane (for example fluconazole , nystatin ).

Candida can be easily grown on simple nutrient media with the addition of antibiotics (to suppress bacterial colonies) and in culture at 37 ° C forms small whitish colonies within one to two days.

Morphology and reproduction

Candida is a polymorphic fungus, i. that is, it forms different forms of growth. The individual fungal cells are roundish-oval and have a diameter of about 4–10 µm (extreme values from the literature). Typical for Candida albicans are both the formation of pseudo mycelia (thread form) and the formation of real hyphae , which, however, are an indication of the no longer saprobiotic , but invasive form of colonization in the context of a manifest infection . Individual mycelial threads can be seen in the examination material with the naked eye.

Candida forms so-called blastoconidia, which arise through sprouting (see conidiogenesis and dehiscence ). Also resting spores , called chlamydospores are a key differentiator of Candida albicans to other yeasts, but also come to a close and also clinically relevant relatives, Candida dubliniensis , above. These chlamydospores form a tough cell wall and are larger than blastoconidia. As a diploid organism, Candida albicans has a genome with a size of 2x16 megabase pairs, which is distributed over 2x8 chromosomes. For a long time this mushroom was not known to have a sexual stage, so that it was one of the Fungi imperfecti . However, recent research suggests that Candida albicans makes use of sexual mechanisms for the exchange of genetic material between different isolates under certain conditions, and that this ability plays a role in the fungus adapting to certain stress conditions.

It has been known since 2013 that C. albicans occurs temporarily in a haploid form, which can be converted back to the diploid form through sexual reproduction or autodiploidization .

Candida albicans microscopically secured in the sputum

Genetic engineering

The C. albicans KEGG genome consists of 14,629 protein-coding genes and 32 RNA-coding genes. 13 other genomes are recorded. The protein structure is available online.

Cariogenicity

The dental caries is a disease of the dental hard tissue dental enamel and dentin . Recent research has shown that the cariogenic Streptococcus mutans interacts with the fungus Candida albicans , which causes the bacterium to change its virulence . The fungus produces signaling molecules that stimulate the bacterium's genes to produce antibiotics in the cell . The bacterium can absorb foreign genetic material through the fungus. Streptococcus mutans forms dextrans , which contribute to the formation of plaque (dental plaque). Microorganisms have special receptors on their cell wall that enable them to bond. The production of sticky substances, an important prerequisite for the adhesion of Streptococcus mutans to the tooth , is supported by the fungus.

Candida albicans in polymicrobial biofilms

The yeast Candida albicans is in symbiosis with many other microbes in the human microbiome , because it contributes to the formation of a biofilm or stimulates them to form a biofilm . Since immune cells can only act against a biofilm to a limited extent, it can also occur in immunocompetent patients z. B. chronic irritation, mild chronic inflammation, joint pain or chronic fatigue. In addition, temporarily administered immunosuppressive drugs (e.g. steroids, cortisone) or infections (influenza) can contribute to the invasive spread of the biofilm. This can lead to chronic irritation and inflammation in the area of the internal organs ( endocarditis , meningitis , endophthalmitis, etc.).

The biofilm favors the exchange of resistance genes between individual bacteria. Furthermore, the yeast fungus Candida albicans produces a secretion that is impermeable to the antibiotic vancomycin and thus protects the bacteria in the biofilm from that antibiotic. It can be assumed that other antibiotics can also be blocked by the secretion. However, the secretion can be solved with antifungal agents (e.g. amphotericin-B, anidulafungin) and some NSAIDs (e.g. ibuprofen and aspirin ). Even in concentrations that are harmless to humans , nitrogen monoxide can stimulate certain microorganisms to dissolve the biofilm.

Individual evidence

↑ K. Nielsen & J. Heitmann: Sex and virulence of human pathogenic fungi. Adv Genet. 2007; 57 : 143-173. PMID 17352904 .

↑ MA Hickman, G. Zeng et al. a .: The 'obligate diploid' Candida albicans forms mating-competent haploids. In: Nature. Volume 494, Number 7435, February 2013, pp. 55-59. doi : 10.1038 / nature11865 . PMID 23364695 . PMC 3583542 (free full text).

↑ http://www.genome.jp/kegg-bin/show_organism?org=cal Kegg

↑ http://www.candidagenome.org/Strains.shtml Candida albicans Strains

↑ D. Reinhardt: Cystic Fibrosis . Springer-Verlag, March 12, 2013, ISBN 978-3-642-56796-4 , p. 141.

↑ H. Sztajer, SP Szafranski, J. Tomasch, M. Reck, M. Nimtz, M. Rohde, I. Wagner-Döbler: Cross-feeding and interkingdom communication in dual-species biofilms of Streptococcus mutans and Candida albicans. In: The ISME journal. Volume 8, Number 11, November 2014, pp. 2256-2271. doi : 10.1038 / ismej.2014.73 . PMID 24824668 .

↑ ^a ^b ^c Melphine M. Harriott, Mairi C. Noverr: Candida albicans and Staphylococcus aureus Form Polymicrobial Biofilms: Effects on Antimicrobial Resistance . In: Antimicrobial Agents and Chemotherapy . tape 53 , no. 9 , September 1, 2009, ISSN 0066-4804 , p. 3914–3922 , doi : 10.1128 / AAC.00657-09 , PMID 19564370 ( asm.org [accessed January 14, 2020]).

↑ Clarissa J. Nobile, Alexander D. Johnson: Candida albicans Biofilms and Human Disease . In: Annual review of microbiology . tape 69 , 2015, ISSN 0066-4227 , p. 71-92 , doi : 10.1146 / annurev-micro-091014-104330 , PMID 26488273 , PMC 4930275 (free full text).

↑ Megan L. Falsetta, Marlise I. Klein, Punsiri M. Colonne, Kathleen Scott-Anne, Stacy Gregoire: Symbiotic relationship between Streptococcus mutans and Candida albicans synergizes virulence of plaque biofilms in vivo . In: Infection and Immunity . tape 82 , no. 5 , May 2014, ISSN 1098-5522 , p. 1968–1981 , doi : 10.1128 / IAI.00087-14 , PMID 24566629 , PMC 3993459 (free full text).

↑ Anikó Kilár, Ágnes Dörnyei, Béla Kocsis: Structural characterization of bacterial lipopolysaccharides with mass spectrometry and on- and off-line separation techniques . In: Mass Spectrometry Reviews . tape 32 , no. 2 , 2013, ISSN 1098-2787 , p. 90–117 , doi : 10.1002 / mas.21352 ( wiley.com [accessed January 14, 2020]).

↑ Melphine M. Harriott, Mairi C. Noverr: Importance of Candida-bacterial polymicrobial biofilms in disease . In: Trends in microbiology . tape 19 , no. November 11 , 2011, ISSN 0966-842X , p. 557-563 , doi : 10.1016 / j.tim.2011.07.004 , PMID 21855346 , PMC 3205277 (free full text).

↑ Scott Chimileski, Michael J Franklin, R Thane Papke: biofilm FORMED by the archaeon Haloferax volcanii exhibit cellular differentiation and social motility, and Facilitate horizontal gene transfer . In: BMC Biology . tape 12 , 14 August 2014, ISSN 1741-7007 , doi : 10.1186 / s12915-014-0065-5 , PMID 25124934 , PMC 4180959 (free full text).

↑ Ona Rogiers, Michelle Holtappels, Wafi Siala, Mohamed Lamkanfi, Françoise Van Bambeke: Anidulafungin increases the antibacterial activity of tigecycline in polymicrobial Candida albicans / Staphylococcus aureus biofilms on intraperitoneally implanted foreign bodies . In: Journal of Antimicrobial Chemotherapy . tape 73 , no. 10 , October 1, 2018, ISSN 0305-7453 , p. 2806–2814 , doi : 10.1093 / jac / dky246 ( oup.com [accessed January 14, 2020]).

^ Mohammed AS Alem, L. Julia Douglas: Effects of Aspirin and Other Nonsteroidal Anti-Inflammatory Drugs on Biofilms and Planktonic Cells of Candida albicans . In: Antimicrobial Agents and Chemotherapy . tape 48 , no. 1 , January 1, 2004, ISSN 0066-4804 , p. 41-47 , doi : 10.1128 / AAC.48.1.41-47.2004 , PMID 14693516 ( asm.org [accessed January 14, 2020]).