Examining the Bactericidal Behavior of a New MRSA Treatment

Daniel Pilch, PhD, associate professor in the Department of Pharmacology at Rutgers Robert Wood Johnson Medical School, co-founder of TAXIS Pharmaceuticals, and co-author of the study, explains the bactericidal behavior of TXA709, a new drug to treat MRSA infections.

Interview Transcript (slightly modified for readability)

“TXA709 is unique in that it has a combination of properties that do enable it to eradicate MRSA from the body, and here’s why. It targets a particular protein termed FtsZ that is essential for bacterial survival. If the function of that protein is disrupted in any way, it causes the death of the bacteria, and, indeed, TXA709 treatment rapidly kills the bacteria that are exposed to it. In fact, it kills bacteria, it kills MRSA, more rapidly than any of the current standard-of-care drugs used to treat MRSA do. Two of those kill, one of those doesn’t even kill, it only inhibits growth. But even the two current standard-of-care drugs that are able to kill MRSA do so much less rapidly than TXA709.

That killing behavior, the term for it is called ‘bactericidal.’ That bactericidal behavior, coupled with what turns out to be very favorable distribution properties in the body of TXA709, enables it to effectively eradicate [MRSA] from inside the body. That said, there are individuals who are carriers of MRSA, typically on their skin. They will always be carriers, and that’s fine, [because] it usually causes them no harm, as long as it remains on the outside of their body. The problem arises when [MRSA] gains a port of entry into the body, and that’s where TXA709 would come in.

The key to a successful [treatment] is to, first of all, make sure that the patient completes the full regimen, and not stop when the symptoms subside. [It’s important to] complete the full regimen, because there can be a limited number of bacteria that have not been killed yet, in the body, and the patient will not feel any symptoms. For a patient to feel ill or experience symptoms from a bacterial infection requires hundreds of millions of bacteria to be present. If there [are] only a few hundred, or a few thousand bacteria, sounds like a lot, but it’s not very many, and the patient won’t feel sick or have any symptoms at all from that few. So, it’s critical to complete the course of the regimen, which should effectively wipe out all of the stragglers.”