Mycobacterium lentiflavum complicating insulin injection sites

Non-tuberculous mycobacteria (NTM)/atypical mycobacteria are opportunistic pathogens ubiquitous in the environment. Recently, NTM cases causing skin and soft tissue infections are on the rise, owing to the improved diagnostic techniques as well as heightened number of procedures. A man in the mid 60s with diabetes, on insulin for the past 20 years, presented with multiple painful swellings, a few of them with pus discharge, over the insulin injection sites of arms, abdomen and thighs for the past 10 months. Local ultrasonography revealed anechoic collections surrounding increased vascularity in the subcutaneous planes. Histopathology showed suppurative inflammation with a large area of necrosis in the lower dermis and subcutaneous fat. Acid-fast bacilli culture grew NTM and was identified as Mycobacterium lentiflavum by PCR followed by Sanger sequencing of the 16S-23S intergenic spacer region. The lesions dramatically improved with clarithromycin and ofloxacin, which were continued for a total of 5 months.