Failure of the Amikacin, Cefoxitin, and Clarithromycin Combination Regimen for Treating Pulmonary Mycobacterium abscessus Infection

In a hollow-fiber model, we mimicked the drug exposures achieved in the lungs of humans treated with standard amikacin, clarithromycin, and cefoxitin combination therapy for Mycobacterium abscessus infection. At optimal dosing, a kill rate of -0.09 (95% confidence interval, -0.04 to 0.03) log(10) CFU per ml/day was achieved over the first 14 days, after which there was regrowth due to acquired drug resistance. Thus, the standard regimen quickly failed. A new regimen is needed.