fections. However, we are seriously concerned that the lack of molecular methods to identify the different genospecies of Acinetobacter in this study makes the conclusions doubtful. A. baumannii is just one genospecies of the group Acinetobacter calcoaceticus-A. baumannii complex (ACB complex), which also includes genospecies A. calcoaceticus, A. nosocomialis, and A. pittii. 2 As they are phenotypically similar and difficult to distinguish using routine laboratory methods, they have been proposed as a group. After the introduction of molecular methods to accurately identify each genospecies, the clinical characteristics of each have been clarified, and it has been better realized that every genospecies has its own distinct features. For example, in the latest study by Lee et al, 3 patients with A. baumannii pneumonia were more likely to have abnormal hematological findings, lobar pneumonia, significantly higher Acute Physiology and Chronic Health Evaluation II scores, and higher mortality than those with A. nosocomialis pneumonia. Thus, they concluded that A. baumannii and A. nosocomialis nosocomial pneumonia are 2 distinct clinical entities. In conclusion, we suggest that molecular methods to precisely identify the ACB complex should be conducted in studies of A. baumannii infections.