"Penicillin, one of the scientific marvels of the 20th century, is currently losing a lot of battles it once won against bacterial infections," researchers said.
Now, scientists at the University of South Carolina have 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, researchers said.
A cyclic four-membered amide ring termed a beta-lactam is a common structural element of the penicillins, their synthetic and semi-synthetic derivatives.
One of the most effective bacterial defences is an enzyme called beta-lactamase, which chews up the beta-lactam structure, researchers said.
Some bacteria, such as MRSA, have developed the ability to biosynthesise and release beta-lactamase when needed.
The new approach by Carolina's Chuanbing Tang pairs the drug with a protective polymer developed in his 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 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 research was published in the Journal of the American Chemical Society.