. Medical and Hospital News .

Rethinking bacterial persistence
by Staff Writers
Lausanne, Switzerland (SPX) Jan 07, 2013

File image.

It's often difficult to completely eliminate a bacterial infection with antibiotics; part of the population usually manages to survive. We've known about this phenomenon for quite some time, dating back nearly to the discovery of penicillin. For more than 50 years, scientists have believed that the resistant bacteria were individuals that had stopped growing and dividing.

Up to now, in fact, it hasn't been possible to track the growth of cells before and after their exposure to antibiotics, which makes any analysis of the phenomenon quite imprecise.

"Using microfluidics, we can now observe every bacterium individually, instead of having to count a population," says John McKinney, director of EPFL's Microbiology and Microsystems Laboratory (LMIC).

Active survivors
This new tool has revealed quite a few surprises. "We thought that surviving bacteria made up a fixed population that stopped dividing, but instead we found that some of them continued to divide and others died. The persistent population is thus very dynamic, and the cells that constitute it are constantly changing - even though the total number of cells remains the same. Because they're dividing, the bacteria can mutate and thus develop resistance in the presence of the antibiotic," explains LMIC scientist Neeraj Dhar.

This point is extremely important. "We were able to eliminate a purely genetic explanation of the phenomenon," continues Dhar. In other words, "a population of genetically identical bacteria consists of individuals with widely varying behavior. Some of them can adapt to stressors that they have not previously encountered, thanks to the selection of persistent individuals. This could lead to a revision of the entire theory of adaptation," says McKinney.

Intermittent efficiency
The EPFL scientists were particularly interested in a relative of the tuberculosis bacterium. Their observations enabled them to formally challenge the argument that persistent bacteria are those that have stopped growing and dividing.

"We were able to reveal the role of an enzyme whose presence is necessary in order for the antibiotic to work, and show that the bacilli produced this enzyme in a pulsatile and random manner," explains Dhar.

"Our measurements showed that bacterial death correlated more closely with the expression of this enzyme than with their growth factor." The research is being published this week in Science magazine.

These conclusions could mark the beginning of a new theory of bacterial resistance, or perhaps even introduce a new view of how such resistance evolves. Further research is being done using other microorganisms, such as tuberculosis and E. coli bacteria. The persistence of some cancer cells to treatment could also be studied in a different manner.

"It's a new approach for trying to figure out why some infections are so difficult to eliminate. The techniques we've developed for this study are now also being used to develop new antibiotics, in collaboration with pharmaceutical companies," says McKinney, adding that "it is the microengineering expertise at EPFL that has enabled us to create these innovative tools and open up new avenues for investigation."


Related Links
Ecole Polytechnique Federale de Lausanne
Hospital and Medical News at InternDaily.com

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Get Our Free Newsletters
Space - Defense - Environment - Energy - Solar - Nuclear


Britain's first hand transplant a success
Leeds, England (UPI) Jan 4, 2013
A British grandfather receiving the country's first hand transplant says he has already gained movement of his fingers following the operation. Former pub owner Mark Cahill, 51, received the new hand to replace a right hand left unusable for five years because of gout and a subsequent infection. Surgeons at Leeds General Infirmary amputated the functionless hand and replaced it with a d ... read more

Obama signs $9.7 bn aid bill for Sandy victims

Congress approves $9.7 bn aid for storm Sandy victims

Obama considers broad arms sales restrictions: report

Fukushima 'unprecedented challenge': new Japan PM

Beidou's unique services attractive to Chinese companies

China eyes greater market share for its GPS rival

Researchers told to ward off navigation system interference

Beidou helps put region on the map

Did Lucy walk, climb, or both?

Study refutes accepted model of memory formation

Fluctuating environment may have driven human evolution

Decision to give a group effort in the brain

Big brains are pricey, guppy study shows

The last link in the chain

Siberian region offers bounty for wolves

Bird watching brings new discoveries

Swine flu kills Jordanian: health minister

Scientists say vaccine temporarily brakes HIV

Penn Team Mimicking a Natural Defense Against Malaria to Develop New Treatments

Swine flu kills nine Palestinians

Protesters gather at China newspaper in censorship row

China labour camp reform revealed - then deleted

German reporter in China says equipment sabotaged

Statue built to reformer whose death sparked Tiananmen

Mexican troops kill 12 suspects in gun battle

Pirates attack ship off Nigeria, kidnap Italian sailors

Four Chinese hostages freed in Colombia

Piracy will swell again if seas not policed: S.African Navy

Walker's World: Merkel's tricky year

Spanish suicides point to worsening crisis

China house prices rise in December

China property tycoon blames government for prices

The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement