Navigation Links
Study: Antibiotics are unique assassins
Date:3/11/2013

In recent years, a body of publications in the microbiology field has challenged all previous knowledge of how antibiotics kill bacteria. "A slew of papers came out studying this phenomenon, suggesting that there is a general mechanism of killing by antibiotics," said Kim Lewis, Northeastern University Distinguished Professor in the Department of Biology and director of Northeastern's Antimicrobial Discovery Center.

The standard thinking at the time was that the three main classes of bactericidal antibiotics each had a unique way of killing bacterial cellslike specialized assassins each trained in a single type of weaponry. But this new research suggested that all antibiotics work the same way, by urging bacterial cells to make compounds called reactive oxygen species, or ROS, which bacteria are naturally susceptible to.

"If they were right it would have been an important finding that could have changed the way we treat patients," said Iris Keren, a senior scientist in Lewis' lab.

And that's exactly how science usually works, said Lewisthrough challenges to mainstream thinking. But recent results reported by Lewis, Keren, and their research partners in an article published Friday in the journal Science suggest that this alternative hypothesis doesn't hold up. For example, even bacteria that are incapable of making ROS are still vulnerable to antibiotics. Further, some antibiotics can work their fatal magic in both aerobic and anaerobic conditionsbut reactive oxygen species can only form when there's oxygen to fuel them.

"We chose to do the simplest and most critical experiment aimed at falsifying this hypothesis," said Lewis. "Killing by antibiotics is unrelated to ROS production," the authors wrote. The findings were corroborated by University of Illinois researchers in another study released on Friday.

The team treated bacterial cultures with antibiotics in both the presence and absence of oxygen. Other than the gaseous environment, the two treatments were identical. There was no difference in cell death between the two populations.

Before performing these experiments, Lewis' team first looked at signals of a fluorescent dye, which previous researchers had used as an indicator for ROS levels. The team treated bacterial cells with a variety of antibiotics and measured the strength of this signal. Since antibiotics were presumed to increase ROS levels, one would have expected increased concentrations of antibiotics to correlate with stronger signals. However, Lewis' group saw no such correlation.

"But there's a difference between correlation and direct observation," Keren said. In order to support their observations with unequivocal data, the team members physically separated the cells that had stronger fluorescent signals from those with weak signals and treated them both with the same antibiotics. Both populations suffered equivalent cell death.

"The research from Dr. Lewis' group demonstrates that, contrary to current dogma, antibiotics apparently do not kill bacteria through induction of reactive oxygen species," said Steven Projan, vice president for research and development at iMed and head of Infectious Diseases and Vaccines at MedImmune, both subsidiaries of AstraZeneca. "The results shown are rather clear but still leave us with the mystery as to how antibacterial drugs help infected people clear bacterial infections. At this point, we should probably dispense with the 'one size fits all' approach to bacterial killing by antibiotics," said Projan, who was not involved in the research.

With these results, Lewis and Keren hope the field will be able to focus its efforts on understanding the true mechanisms of how antibiotics wipe out bacteria in order to effectively address chronic bacterial infections, one of the most pressing issues facing public health today.


'/>"/>

Contact: Lori Lennon
l.lennon@neu.edu
617-680-5129
Northeastern University College of Science
Source:Eurekalert

Related biology news :

1. BYU study: Using a gun in bear encounters doesnt make you safer
2. 15-year study: When it comes to creating wetlands, Mother Nature is in charge
3. Study: Exercise can lead to female orgasm, sexual pleasure
4. U of I study: Lose body weight before gaining baby weight
5. Study: Men who do load-bearing exercise in early 20s may be shielded from osteoporosis
6. USF study: Common fungicide wreaks havoc on freshwater ecosystems
7. Army study: DNA vaccine and duck eggs protect against hantavirus disease
8. Study: In-patient, out-patient stroke rehab might benefit from yoga
9. Study: Seeking Arctic methane has serious implications for Florida coastline
10. Study: Seeping Arctic methane has serious implications for Florida coastline
11. Study: No-fat, low-fat dressings dont get most nutrients out of salads
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/26/2016)... and LONDON , ... Finacle, part of EdgeVerve Systems, a product subsidiary ... Onegini today announced a partnership to integrate the ...      (Logo: http://photos.prnewswire.com/prnh/20151104/283829LOGO ) ... provide their customers enhanced security to access and ...
(Date:4/15/2016)... , April 15, 2016 ... the,  "Global Gait Biometrics Market 2016-2020,"  report to ... http://photos.prnewswire.com/prnh/20160330/349511LOGO ) , ,The global gait biometrics ... of 13.98% during the period 2016-2020. ... angles, which can be used to compute factors ...
(Date:3/31/2016)...  Genomics firm Nabsys has completed a financial  restructuring ... , M.D., who returned to the company in October ... team, including Chief Technology Officer, John Oliver , ... and Vice President of Software and Informatics, Michael ... Dr. Bready served as CEO of Nabsys from 2005-2014 ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... 27, 2016 , ... Rolf K. Hoffmann, former senior vice ... University of North Carolina Kenan-Flagler Business School effective June 27. , ... with a focus on the school’s international efforts, leading classes and participating in ...
(Date:6/24/2016)... ... June 24, 2016 , ... While the majority of commercial spectrophotometers and ... and the 6000i models are higher end machines that use the more unconventional z-dimension ... light beam from the bottom of the cuvette holder. , FireflySci has developed ...
(Date:6/23/2016)... 2016 /PRNewswire/ - FACIT has announced the creation ... biotechnology company, Propellon Therapeutics Inc. ("Propellon" or "the ... a portfolio of first-in-class WDR5 inhibitors for the ... WDR5 represent an exciting class of therapies, possessing ... for cancer patients. Substantial advances have been achieved ...
(Date:6/23/2016)... NEW YORK , June, 23, 2016  The ... students to envision new ways to harness living systems ... of Modern Art (MoMA) in New York ... more than 130 participating students, showcased projects at MoMA,s ... included Paola Antonelli , MoMA,s senior curator of ...
Breaking Biology Technology: