Two heads are better than one, but using 2 (or more) antibiotics at the same time is usually — but not always — equally or less effective. As burgeoning antibiotic resistance makes infections harder and harder to fight, a group of biologists from UCLA have created a mathematical formula that can predict which of the myriad possible combinations of drugs will actually be synergistic, resulting in infection-fighting efficacy that's greater than the sum of the parts.
Using lab-developed E. Coli, the team tested every possible combination of 6 different antibiotics, including the 20 possible combinations of 3 in particular. Two of those combinations produced a combined bacteria-killing efficacy that exceeded expectations. (Five other 3-drug combinations were less effective than expected, and the other 13 did about as well as the team predicted.)
What made the 2 powerful combinations work so well? Each involved 3 different classes of antibiotics, so together they employed a wide range of bacteria-fighting mechanisms.
The team is now using the formula to test combinations of 4 antibiotics. It's a start, they say, adding that more research is needed to determine which combinations would be best for specific diseases and specific body parts.