LUBBOCK, Texas, Sept. 11 (UPI) -- A recently patented chemical additive could make old antibiotics effective again against resistant bacteria, a Texas Tech researcher said.

A short chain of nucleic acid, called an aptamer, can stop antibiotic-resistant bacteria from breaking down antibiotics, said Robert Shaw, associate chairman of Texas Tech's Department of Chemistry.

Aptamers could invigorate beta-lactam antibiotics, such as penicillins, carbapenems and cephalosporins, which account for nearly $30 billion in annual sales in the United States and more worldwide, Shaw said in a release.

Aptamers used with antibiotics kill bacteria that produce enzymes called metallo-beta-lactamase, which have been the most difficult enzymes for researchers to counteract, Shaw said.

Bacteria become antibiotic-resistant when they exchange genetic information on how to make these enzymes, Shaw said in an edition of Chemical Biology and Drug Design covering the best presentations of the 2008 International Symposium on Organic Synthesis and Drug Discovery.