Stephenson D, et al. - In this study with patients with cystic fibrosis (CF) (405 samples), bronchiectasis (323 samples) and other lung diseases requiring lung transplantation (274 samples), researchers assessed “rapidly-growing mycobacteria” (RGM) medium for the detection of nontuberculous mycobacteria (NTM). They analyzed 1,002 respiratory samples from 676 patients. They compared direct culture on RGM medium, with incubation at two temperatures (30 °C and 37 °C) vs conventional culture of decontaminated samples for acid-fast bacilli (AFB) using both a solid medium (Löwenstein-Jensen medium) and a liquid medium (the Mycobacterial Growth Indicator Tube; MGIT). On RGM at 30 °C (RGM medium incubated at 30 °C for 28 days) vs AFB culture, significantly more isolates of Mycobacterium abscessus complex were isolated. This investigation represents the largest study of RGM medium to date, wherein the utility of RGM medium for isolation of NTM from patients with CF was reaffirmed. RGM medium showed efficacy as a tool for culture of respiratory samples from patients with bronchiectasis and other lung diseases.