Bacteria create routes by surgical implants to infect patients

Sydney (Australia), 25 jun (EFE).-a group of Australian scientists discovered an important key in the fight against post-operative infections by observing the spread of the bacteria through viscous biofilms that form in implants medical, local media reported today.

bacteria build a complex transportation network using deoxyribonucleic acid to mark the paths on the viscous layers that form above the implant, according to the study led by Cynthia Whitchurch, microbiologist from the University of technology of Sydney.

"Following one another and obeying the rules, they (bacteria) can move with enough efficiency across the network", Whitchurch told the local chain ABC.

These viscous biofilms help make bacteria resistant to antibiotics and disinfectants, as well as the immune system of the human organism.

"Probably half of infections acquired in hospitals are due to the biofilm formed in implant doctors, such as catheters", said the Australian microbiologist.

To study how are they formed and expand these biofilms in new areas of a living organism, researchers focused their attention on tracking the movements of the bacterium Pseudomonas aeruginosa, commonly causing urinary and respiratory infections.

"For the first time we were able to obtain quantitative data of the individual cell movements during the process of the expansion of bio-films," said Whitchurch.

Thus, researchers observed how cells are lined in a coordinated manner to mark trails and how built these furrows expelling DNA to organize movements.

But when scientists destroyed these roads of DNA with enzymes, they noticed that they altered the translocation of bacteria.

"They began to rebound as individual cells and ended up in traffic jams and the expansion rate of the biofilm shrank," added Whitchurch.

In addition, the scientists found that DNA helps the bacteria to keep seals to new grooves that allow for the displacement of the other.

"They can not be moved individually in New Territories, they have to do collectively," said Whitchurch, after emphasizing that their research will contribute to control its expansion in medical implants.

An alternative would be the insert small furrows in the implants to limit the expansion of this viscous biofilm and forcing the bacteria to "go in useless circles, instead of leaving them to coordinate their movements on the apparatus", according to microbiologist. EFE

y Finalmente como se reporto la investigación en Pubmed

http://www.ncbi.nlm.nih.gov/pubmed/23798445

Artículo a texto completo:

http://www.pnas.org/content/early/2013/06/21/1218898110.long

2013 Jun 24. [Epub ahead of print]

Self-organization of bacterial biofilms is facilitated by extracellular DNA.

Gloag ES, Turnbull L, Huang A, Vallotton P, Wang H, Nolan LM, Mililli L, Hunt C, Lu J, Osvath SR, Monahan LG, Cavaliere R, Charles IG, Wand MP, Gee ML,Prabhakar R, Whitchurch CB.

Source

The ithree institute and School of Mathematical Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.

Abstract

Twitching motility-mediated biofilm expansion is a complex, multicellular behavior that enables the active colonization of surfaces by many species of bacteria. In this study we have explored the emergence of intricate network patterns of interconnected trails that form in actively expanding biofilms of Pseudomonas aeruginosa. We have used high-resolution, phase-contrast time-lapse microscopy and developed sophisticated computer vision algorithms to track and analyze individual cell movements during expansion of P. aeruginosa biofilms. We have also used atomic force microscopy to examine the topography of the substrate underneath the expanding biofilm. Our analyses reveal that at the leading edge of the biofilm, highly coherent groups of bacteria migrate across the surface of the semisolid media and in doing so create furrows along which following cells preferentially migrate. This leads to the emergence of a network of trails that guide mass transit toward the leading edges of the biofilm. We have also determined that extracellular DNA (eDNA) facilitates efficient traffic flow throughout the furrow network by maintaining coherent cell alignments, thereby avoiding traffic jams and ensuring an efficient supply of cells to the migrating front. Our analyses reveal that eDNA also coordinates the movements of cells in the leading edge vanguard rafts and is required for the assembly of cells into the "bulldozer" aggregates that forge the interconnecting furrows. Our observations have revealed that large-scale self-organization of cells in actively expanding biofilms of P. aeruginosa occurs through construction of an intricate network of furrows that is facilitated by eDNA.