Featured Research

from universities, journals, and other organizations

Low levels of antibiotics cause multidrug resistance in 'superbugs'

Date:
February 12, 2010
Source:
Boston University College of Engineering
Summary:
A new study by biomedical engineers indicates that treating bacteria with levels of antibiotics insufficient to kill them produces germs that are cross-resistant to a wide range of antibiotics.

For years, doctors have warned patients to finish their antibiotic prescriptions or risk a renewed infection by a "superbug" that can mount a more powerful defense against the same drug. But a new study by Boston University biomedical engineers indicates that treating bacteria with levels of antibiotics insufficient to kill them produces germs that are cross-resistant to a wide range of antibiotics.

Related Articles


In the Feb. 12 issue of Molecular Cell, research led by Boston University Professor James J. Collins details for the first time the biomolecular process that produces superbugs. When administered in lethal levels, antibiotics trigger a fatal chain reaction within the bacteria that shreds the cell's DNA. But, when the level of antibiotic is less than lethal the same reaction causes DNA mutations that are not only survivable, but actually protect the bacteria from numerous antibiotics beyond the one it was exposed to.

"In effect, what doesn't kill them makes them stronger," said Collins, who is also a Howard Hughes Medical Institute investigator. "These findings drive home the need for tighter regulations on the use of antibiotics, especially in agriculture; for doctors to be more disciplined in their prescription of antibiotics; and for patients to be more disciplined in following their prescriptions."

Two years ago, Collins -- together with graduate student Michael Kohanski and post-doctoral fellow Mark DePristo -- proved that when applied in lethal doses, antibiotics stimulate the production of reactive oxygen species (ROS) molecules, or free radicals that damage DNA, protein and lipids in bacterial cells, contributing to their demise. In the new study, the same co-authors demonstrated that the free radicals produced by a sub-lethal dose of an antibiotic accelerate mutations that protect against a variety of antibiotics other than the administered drug.

"We know free radicals damage DNA, and when that happens, DNA repair systems get called into play that are known to introduce mistakes, or mutations," said Collins. "We arrived at the hypothesis that sub-lethal levels of antibiotics could bump up the mutation rate via the production of free radicals, and lead to the dramatic emergence of multi-drug resistance."

Testing their hypothesis on strains of E. coli and Staphylococcus, the researchers administered sub-lethal levels of five kinds of antibiotics and showed that each boosted levels of ROS and mutations in the bacterial DNA. They next conducted a series of experiments to show that bacteria initially subjected to a sub-lethal dose of one of the antibiotics exhibited cross-resistance to a number of the other antibiotics. Finally, they sequenced the genes known to cause resistance to each antibiotic and pinpointed the mutations that protected the bacteria. Ironically, the researchers discovered that in some cases the bacteria were still be susceptible to the original antibiotic.

"The sub-lethal levels dramatically drove up the mutation levels, and produced a wide array of mutations," Collins observed. "Because you're not killing with the antibiotics, you're allowing many different types of mutants to survive. We discovered that in this zoo of mutants, you can actually have a mutant that could be killed by the antibiotic that produced the mutation but, as a result of its mutation, be resistant to other antibiotics."

The group's findings underscore the potentially serious consequences to public health of administering antibiotics in low or incomplete doses. This is common practice among farmers who apply low levels of antibiotics to livestock feed; doctors who prescribe low levels of antibiotics as placebos for people with viral infections; and patients who don't follow the full course of antibiotic treatment.

The study's findings may ultimately lead to the development of new antibiotic treatments enhanced with compounds designed to prevent the emergence of multi-drug resistance. For example, one potential treatment might inhibit the DNA damage repair systems that lead to the problematic mutations, while another might boost production of cell-destroying free radicals so that a low dose of antibiotic is sufficient to kill targeted bacterial cells.


Story Source:

The above story is based on materials provided by Boston University College of Engineering. Note: Materials may be edited for content and length.


Journal Reference:

  1. Michael A. Kohanski, Mark A. DePristo, James J. Collins. Sublethal Antibiotic Treatment Leads to Multidrug Resistance via Radical-Induced Mutagenesis. Molecular Cell, Volume 37, Issue 3, 311-320, 12 February 2010 DOI: 10.1016/j.molcel.2010.01.003

Cite This Page:

Boston University College of Engineering. "Low levels of antibiotics cause multidrug resistance in 'superbugs'." ScienceDaily. ScienceDaily, 12 February 2010. <www.sciencedaily.com/releases/2010/02/100211151647.htm>.
Boston University College of Engineering. (2010, February 12). Low levels of antibiotics cause multidrug resistance in 'superbugs'. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2010/02/100211151647.htm
Boston University College of Engineering. "Low levels of antibiotics cause multidrug resistance in 'superbugs'." ScienceDaily. www.sciencedaily.com/releases/2010/02/100211151647.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins