What is the Role of Combination Therapy in Treating S. aureus Infections?

Prof. Josh Davis, MBBS, PhD, Principle Research Fellow, Menzies School of Health Research, Australia, discusses the role of combination therapy when it comes to treating invasive Staphylococcus aureus infections.

Interview Transcript (slightly modified for readability)

“The role of combination therapy in invasive Staphylococcus [aureus] infections is really not completely defined yet, though a lot of research has been done on [multiple] different combinations. At present, none of those combinations has been shown to be clinically superior to just standard monotherapy.

However, there is one promising set of combination therapies that we are working on further, and that’s combining beta-lactam antibiotics with standard therapy, and the standard therapy being either vancomycin or daptomycin.

So, for the other combination therapies apart from beta-lactam, they’ve all been shown either not to work or to cause more harm than good. An example is adding gentamicin to nafcillin—it does shorten the duration of bacteremia by about a day, but it doesn’t improve mortality and it causes more renal failure. So, that’s not recommended. Rifampicin, a recent trial has just been finished, called the ARREST trial, which [found] absolutely no benefit in adding rifampicin to standard therapy, and then there are several other agents, which also have not been shown to be of any benefit.

Beta-lactams, in vitro, in the laboratory, nearly all beta-lactams show synergy against MRSA, [methicillin-] resistant Staph aureus and [heterogenous vancomycin-intermediate Staphylococcus aureus] hVISA, when combined with either vancomycin or daptomycin, and there is some limited human data, but not enough yet to say that it’s superior to monotherapy. We’re currently running a large, randomized trial to try to answer that question.”