Tuesday, 20 March 2012

The recent advance in the genetics of dermatophytes


The recent advance in the genetics of dermatophytes (Samuel Kang 42833842)

General issues

  • Dermatophytological infectious disease is currently affecting 10 to 20 percent of global population (Grumby, Monold & Staib, 2011, p80). 
  • Resulting in treatment cost of nearly a half billion dollars in the USA (Marques et al, 2000). 
 What is a a dermatophytes?
  • Dermatophytes are the most common fungal infection, affecting human skin, scalps and nails (Degreef, 2008, pp257-265). Athlete's foot and ringworm infection is the most common example. Currently, 40 dermatophytes species are known to exist globally (Weitzman & Summerbell, 1995). According to Chand and Ghannoum (2012, p89), dermatophytes are very complex filamentous fungi, able to undergo proteolysis on keratinized host structures’ epidermis and nails. These fungi can break down the peptide bond in the protein structure (keratin) of skin and nails, using a cellular enzyme called protease, and then reproduce (Ajello 1974, pp.93-110). Depending on the nature of their host, there are three types of dermotaphytes: anthropohilic, zoophilic and geophilic. Geophilics are soil saprophytes, whereas anthrophilies and zoophilies are found in animals and cause chronic infection and inflammation (Weitzman & Summerbell, 1995, pp 240-259). 
 Is it dangerous?
  •  Fortunately, Bogers, Degreef and Cauwenbergh (2005, pp749-862) state that these infections are not deadly, however they occur regularly in people with a poor immune system and in some cases “are long lasting, recurrent and difficult to cure.”  It is now very common to find articles about dermatophyte epidemiology and its clinical importance,
 Then why research about dermatophyte?

  • Vermout et al (2008, pp267-275) and Brasch (2009, pp 302-312) both claim that these dermatophytes’ pathogenesis and their adaptations to various environments are far more complex. Furthermore, their pathophysiological reaction is relatively unknown to describe the relationship to various dermatophyte infectious diseases. Plus, identification of dermatophytosis caused by theses species is very difficult. Therefore, various genetic research has been conducted for the last ten years.

What has happened for last 10 years

  • Completely sequenced genomes of seven different dermatophytes species were discovered. These available gnomes are used in the bio informatics approach to predict whether the species is virulent or not (Achterman & White, 2011, p.8).
  • Other genomes sequencing techniques such as , expressed sequence tag (EST) sequencing and cDNA based microarrays analysis allow a deeper insight into cellular adaptation at the level of gene expression(Grumby, Monod & Staib, 2011, p80) and also identified that not only keratinase but 23 other protease genes are involved in undergoing enzyme activity (Zaugg et al, 2009).
  • Liu et al (2007) as cited in Peres et al (2010) discovered that some exposure to a drug actually stimulates the transcription of several multidrug resistances.
There is still far more to be discovered discovery and this field of research has broader prospects in the future. 

Now What? 
  • There are still more aspects of dermatophytes that need to be investigated. Grumby, Monod and Staib (2011, p80) mention that manipulation of protein degradation genes are yet to be proceeded since the genes of dermatophytes are less willing to undergo transformation. The identification of virulent factors of dermatophytes is still at the beginning stage (Arterman & White, 2011, p.8). 


Once further investigation is conducted, it is likely to see that diagnosis and other clinical approaches will be vastly improved.



REFERENCE

Achterman, R & White,T 2012, ‘Dermatophye virulence factors: identifying and analysing genes that may contribute to chronic or acute skin infections’, Internation Journal of Biology, vol. 2012, article ID 358305, doi:10.1155/2012/358305, p.8.

Ajello,L 1974, ‘Natural history of the dermatophytes and related fungi’, Mycopathologia et Mycologia applicata,vol.53, pp.93-110.

Bogers, M, Degreef,H & Cauwenbergh, G 2005,’Fungal infections of the skin: infection process and antimycotic therapy, Current Drug Targets, vol. 6, pp749.862.

Brasch, J 2009,‘Current knowledge of host response in human tinea’, Mycoses, vol.52, pp 302-312.

Chand,D & Ghannoum, M 2012, ‘Susceptibility testing of dermatophytes’, in Hall GS (ed.), Interactions of Yeasts, Moulds and Antifungal Agents: How to Detect Resistance, Springer, p89.
Degreef,H 2008, ‘Clinical forms of dermatophytosis (ringworm infection)’, Mycopathologia, vol.166, pp257-265.

Grumbt,M, Monold, M & Staib, P 2011, ‘Genetic advances in dermatophytes’, FEMS Microbiology Letters, vol. 320, no. 2, pp 79–86, viewed 16 March 2012,<http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6968.2011.02276.x/abstract>.

Harmsen, D, Schwinn, A , Brocker, F & Frosh, M 1999, ‘Molecular differentiation of dermatophyte fungi’,  Mycoses, vol. 42, Issue 1-2, pp 67–70.

Peres,N, Sanches,p, Falcão,J, Silveira,H, Paião,F,  Maranhão, F,  Gras,D, Segato,F, Cazzaniga,R, Mazucato, M,  Cursino-Santos,J, Aquino-Ferreira,R,  Rossi, A &  Martinez-Rossi, N 2010, ‘Transcriptional profiling reaveals the expression of novel genes in response to various stimuli in the human dermatophyte Trichonphyton rubrrum’, BMC Microbiology Research Articles, vol.10, no.39, pp.1-10.

Vermout,S, Tabart, S, Baldo, A, Mathy, A, Losson,B &Mignon, B 2008, ‘Pathogenesis of dermatophyosis’, Mycopathologia, vol.166, pp267-275.
Weitzman, I & Summerbell,R.C 1995, ‘The dermatophytes’, Clinical Microbiology Review, vol.8, pp 240-259.

Zaugg,C ,Monon, M, Weber,J, et al 2009, ‘Gene expression profiling in the human pathogenic dermatophtye Trichophyton rubrum during growth on proteins’, Eukaryot cell, vol.8,no.2, pp 241–250.

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