Rapidly Growing Mycobacterial Infections of the Skin and Soft Tissues Caused by M. fortuitum and M. chelonae

Purpose of ReviewNon-tuberculous mycobacteria (NTM) have emerged as pathogens of clinical importance in human health as etiological agents of opportunist infections. Although NTM are known to cause systemic infections in immunocompromised subjects primarily in HIV patients, yet the growing number of immunosuppressed patients with new therapies and even more recently in non-immunocompromised subjects often localized infections of the lungs or skin and soft tissues (S&STI) but with a new clinical spectrums. Our goal is to report distinct patterns of infections according to the clinical and immunological settings and management options.Recent FindingsMycobacteria are efficacious pathogens because of their ability to survive and reproduce within the macrophages because of mechanisms of evasion of the host defenses and also because of their capacity to produce biofilms that facilitate their permanence in environmental reservoirs. Thus, both community and healthcare-associated infections have been reported. Also, we emphasize the concept of the new NTM complex of rapid growing Mycobacterium fortuitum-vaccae and Mycobacterium abscessus-chelonae (RGM) based on genetic and molecular characteristics that differentiate members according to the 16S rRNA gene clade and overall genome similarity.SummaryS(&)STI by RGM should be considered when response to standard antibiotic therapy is deficient and microbiological work-up is negative. Effective treatment of these RGM pathogens includes surgical treatment with combined antimicrobial therapy; resistance to first-line anti-tuberculous drugs is common so therapy should be based on in vitro susceptibility testing. More clinical studies due to a lack of standard guidelines for the treatment of RGM infections are needed.