Strategies to Improve Outcome of Drug Treatment for Mycobacterium abscessus Pulmonary Disease

To the Editor—In the May 2011 issue of Clinical Infectious Diseases, Jarand et al [1] reported on the outcome of treatment in their cohort of patients with Mycobacterium abscessus pulmonary disease. Despite optimal regimens, only 33 (48%) of 69 patients experienced conversion to negative culture results. Outcome was significantly worse in patients who received drug treatment only, without adjunctive surgical treatment (28% vs 57%). In his editorial, Griffith [2] placed these findings in a historical context, one that leaves little room for optimism. Simply put, antibiotic treatment alone has little to offer; this leaves one to wonder why it has little to offer. Study of the M. abscessus genome offers some interesting insights. As Jarand et al [1] note, the existence of an erythromycin resistance methylase (erm) gene implies that M. abscessus bacteria can induce macrolide resistance [1]. The genome, however, has additional disconcerting features: an additional erm-like gene, multiple efflux pumps, an aminoglycoside 2’-N-acetyltransferase, and 12 homologs of aminoglycoside phosphotransferases [3]. What do these aminoglycoside-converting enzymes mean for the efficacy of amikacin, the second most important drug after the macrolides in