Evolution being what it is, the ongoing battle between antibiotics and bacteria is constantly in flux, though it looks like the antibiotics are fighting back from what seemed to be a losing position:
Researchers from North Carolina State University have increased the potency of a compound that reactivates antibiotics against methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant form of Staphylococcus that is notoriously difficult to treat. Their improved compound removes the bacteria’s antibiotic resistance and allows the antibiotic to once again become effective at normal dosage levels.
The compound had been developed earlier, but the quantity of it then required to make a dent in the bacteria’s protective shield made it otherwise problematic. How it operates:
The compound works by short-circuiting the bacteria’s ability to mount a defense against the antibiotic. When antibiotics interact with bacteria, receptors on the surface of the bacteria identify the antibiotic as a threat and the bacteria can then choose what to do to survive. MRSA either creates a biofilm or makes genetic changes that prevent the antibiotic from disrupting its cell structure. According to [chemist Christian] Melander, “We believe that our compound renders the bacteria unable to recognize the antibiotic as a threat, essentially stopping the defensive process before it can begin.”
Citation: “Potent Smal-Molecule Suppression of Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus” by Tyler L. Harris, Robert J. Worthington and Christian Melander, North Carolina State University, Angewandte Chemie, 2012.