Rapidly mutating yeast causing more infections

A yeast named Candida glabrata commonly occurs in humans, usually on our skin. It does little harm there. But if it enters the blood system, it can be directly life threatening to people with poor immune defense, such as cancer and AIDS patients.

“It can actually eat you up from the inside,” says Jure Piškur, professor at the Department of Cell and Organism Biology at the Lund University.

Jure Piškur, together with a team of research colleagues, has studied the underlying reasons that this yeast can cause more and more infections in humans. The research team has discovered that Candida glabrata can mutate surprisingly rapidly. Instead of mutations occurring in individual genes, this yeast can mutate by reorganizing their chromosomes and make extra copies of large chromosome pieces.

The consequence of this is that Candida glabrata is becoming more and more resistant to fungicidal medicine. The present research report shows that a certain mini-chromosome can enable the yeast fungus to survive even if it is treated with nearly ten times the normal dose of the fungicide fluconazole.

“Our research now aims to identify the weak points in Candida glabrata so that we can develop effective medicine,” says Jure Piškur.

Candida glabrata has become the second most common yeast pathogen in humans. It primarily causes irritation, in the genitals, for instance. Jure Piškur stresses that people whose immune defense is normal run very little risk of being affected by the life-threatening form of fungal infection in the blood system.

The most common type of fungus in humans is called Candida albicans and causes commonly occurring infections in women's genitals. This yeast fungus is relatively easy to treat with fungicides. But more and more often after the treatment Candida albicans is replaced with the more resistant Candida glabrata.

The research findings regarding Candida glabrata were recently presented in two scientific journals, PNAS and Nature Review Microbiology.

PNAS 2009 106:2688-2693; published online before print February 9, 2009, doi:10.1073/pnas.0809793106

Fungal Pathogenesis: Varying for virulence
Nature Reviews Microbiology 7, 256 – 257 (01 Apr 2009), doi: 10.1038/nrmicro2125, Research Highlight

For more information, please contact Jure Piškur, phone: +46 (0)46 – 222 83 73 or Jure.Piskur@cob.lu.se

Pressofficer Lena Björk Blixt; Lena.Bjork_Blixt@kanslin.lu.se;+46-46 222 71 86

Facts about chromosomes and genes:
Chromosomes are the structures that all genes sit on. If the genome is seen as a book and chromosomes as the pages of the book, then genes are the words on each page. Instead of individual words changing, which is what happens in normal mutations, in C. glabrata its pages are mixed and in certain cases also copied and placed in the book in a new order. The genes are thus the same as before, but the genetic make-up as a whole is altered and this likely influences the gene expression.