Featured Research

from universities, journals, and other organizations

Penicillin redux: Rearming proven warriors for the 21st century

Date:
April 14, 2014
Source:
University of South Carolina
Summary:
Drug-resistant bacteria like MRSA are hard to treat because so many antibiotics are ineffective against them. A team of researchers has shown a new way to reclaim the power of penicillin and similar drugs against so-called "superbugs." "In the United States every year, around 100,000 patients die of bacteria-induced infections," a researcher said. "And the problem is increasing because bacteria are building resistance. It's a really, really big problem, not only for individual patients, but also for society."

Chemistry professor Chuanbing Tang leads a team that has shown a new way to reclaim the power of penicillin and similar drugs against so-called “superbugs.”
Credit: Image courtesy of University of South Carolina

Penicillin, one of the scientific marvels of the 20th century, is currently losing a lot of battles it once won against bacterial infections. But scientists at the University of South Carolina have just reported a new approach to restoring its combat effectiveness, even against so-called "superbugs."

Bacteria have been chipping away at the power of the penicillin family of drugs since their first wide-scale use as antibiotics in the 1940s. For example, the staph infection, brought about by the bacterium Staphylococcus aureus, was once readily treated with penicillin and its molecular cousins.

But that bug has changed. In the 1960s, a new strain arrived, termed MRSA for methicillin- (or sometimes multidrug-) resistant S. aureus. It has become a serious public health problem because the earliest deployed antibiotics are often useless against the new strain, and its prevalence has only increased since it was first observed. MRSA (pronounced mer-suh) is sometimes called a superbug because of the difficulty physicians have in treating infected patients.

The S. aureus microbe has evolved the MRSA strain by developing a variety of defenses against antibiotics to which they've been exposed. One of those defenses effectively neutralizes penicillin's greatest strength.

That strength is its molecular core, a cyclic four-membered amide ring termed a beta-lactam. It is a common structural element of the penicillins, their synthetic and semi-synthetic derivatives, and other related molecules that constitute the broad family of drugs called the beta-lactam antibiotics. Just a few examples (of dozens) include amoxicillin, ampicillin and cefazolin.

The beta-lactam structure in a molecule is something that many bacteria don't like at all. It greatly hinders their ability to reproduce by cell division, and so chemists have for years spent time making molecules that all contain the beta-lactam structural motif, but differ in the surrounding molecular "shrubbery." Physicians heavily use the many versions of beta-lactam antibiotics to fight bacterial infections, and many have been retired because they're no longer effective against the defenses bacteria have evolved in response.

One of the most effective bacterial defenses is an enzyme called beta-lactamase, which chews up the beta-lactam structure. Some bacteria, such as MRSA, have developed the ability to biosynthesize and release beta-lactamase when needed. It's a devastating defense because it's so general, targeting the common structural motif in all of the many beta-lactam antibiotics.

But that also creates the opportunity for a general approach to solving the problem, which is what Carolina's Chuanbing Tang and colleagues just reported in the Journal of the American Chemical Society.

"Instead of developing new antibiotics, here we ask the question, 'can we recycle the old antibiotics?' " he said. "With traditional antibiotics like penicillin G, amoxicillin, ampicillin and so on, can we give them new life?"

The approach pairs the drug with a protective polymer developed in Tang's chemistry laboratory. In lab tests, graduate student Jiuyang Zhang prepared a cobaltocenium metallopolymer that greatly slowed the destructiveness of beta-lactamase on a model beta-lactam molecule (nitrocefin).

The interdisciplinary team, which included Mitzi Nagarkatti and Alan Decho, from the university's School of Medicine and Arnold School of Public Health, respectively, also showed that the antimicrobial effectiveness of the four beta-lactams studied in detail was enhanced by the polymer. The enhancement was modest against two strains, but very pronounced with the hospital-associated strain of MRSA (HA-MRSA).

The metallopolymer by itself even demonstrated antimicrobial properties, lysing bacterial cells while leaving human red blood cells unaffected. By a variety of measures, the polymer was found to be nontoxic to human cells in laboratory tests.

The project is still far from clinical use, but Tang knows moving forward is imperative.

"In the United States every year, around 100,000 patients die of bacteria-induced infections," Tang said. "And the problem is increasing because bacteria are building resistance. It's a really, really big problem, not only for individual patients, but also for society."


Story Source:

The above story is based on materials provided by University of South Carolina. The original article was written by Steven Powell. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jiuyang Zhang, Yung Pin Chen, Kristen P. Miller, Mitra S. Ganewatta, Marpe Bam, Yi Yan, Mitzi Nagarkatti, Alan W. Decho, Chuanbing Tang. Antimicrobial Metallopolymers and Their Bioconjugates with Conventional Antibiotics against Multidrug-Resistant Bacteria. Journal of the American Chemical Society, 2014; 136 (13): 4873 DOI: 10.1021/ja5011338

Cite This Page:

University of South Carolina. "Penicillin redux: Rearming proven warriors for the 21st century." ScienceDaily. ScienceDaily, 14 April 2014. <www.sciencedaily.com/releases/2014/04/140414154454.htm>.
University of South Carolina. (2014, April 14). Penicillin redux: Rearming proven warriors for the 21st century. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2014/04/140414154454.htm
University of South Carolina. "Penicillin redux: Rearming proven warriors for the 21st century." ScienceDaily. www.sciencedaily.com/releases/2014/04/140414154454.htm (accessed July 29, 2014).

Share This




More Plants & Animals News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
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:
from the past week

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