Rapidly growing mycobacteria

The history of the major pathogenic species of rapidly growing mycobacteria (RGM) can be traced back to the early 20th century beginning with Friedmann's recovery of Mycobacterium chelonae from the lungs of two sea turtles. Currently, the RGM are grouped into six major taxonomic groups according to pigmentation and genetic relatedness. The major groups are the M. fortuitum group, the M. chelonae/M. abscessus group, the Mycobacterium smegmatis group (M. smegmatis and Mycobacterium goodii), the Mycobacterium mucogenicum group, the Mycobacterium mageritense/Mycobacterium wolinskyi group, and the pigmented RGM. The RGM are ubiquitous in the environment. The disease pathogenesis likely results from microtrauma caused by shaving the legs prior to pedicures and footbath water that is heavily contaminated with RGM due to failure to routinely clear the footbath filters. High-Performance Liquid Chromatography (HPLC) of mycolic acids may be used in large reference laboratories but it can identify only a few species adequately. Restriction fragment length polymorphism analysis of selected gene targets such as hsp65 are currently used in some larger reference laboratories. Currently, the only nucleic acid probe available for identification of the RGM but not yet cleared by the Food and Drug Administration in the United States is the INNO- LiPA multiplex probe assay. Current antimicrobial regimens for treatment of disease caused by the RGM are based upon their unique in vitro susceptibility patterns. Finally, the chapter describes common clinical diseases caused due to RGM.