Comparative survival of environmental and clinical Mycobacterium abscessus isolates in a variety of diverse host cells

Aims Mycobacterium abscessus subsp. abscessus (MABS) is an emerging, opportunistic pathogen found globally in freshwater biofilms and soil. Typically, isolates are treated as a uniform group of organisms and very little is known about their comparative survival in healthy host cells. We posit that environmentally- and clinically derived isolates, show differential infectivity in immune cells and resistance to innate defenses. Methods and Results Six MABS isolates were tested including three water biofilm/soil and three sputum-derived isolates. A clinical MABS type strain and an environmental isolate of Arthrobacter were also included. MABS counts were significantly higher compared to Arthrobacter after co-culture with Acanthamoeba lenticulata, BEAS-2B epithelial cells, alveolar macrophages and the THP-1 macrophage cell line. A rough sputum-derived MABS isolate emerged as an isolate with higher virulence compared to others tested, as both a pellicle and cord former, survivor in the human cell models tested, inducer of high and prolonged production of pro-inflammatory cytokines, and the capacity to evade LL-37. Conclusions Findings support intraspecies variation between MABS isolates. Significance and Impact of the Study These data indicate subversion of host immune defenses by environmental and clinical MABS isolates is nuanced and maybe isolate dependent, providing new information regarding the pathogenesis of NTM infections.

Automated summary

Intraspecies variation between Mycobacterium abscessus subsp. abscessus isolates results in differential infectivity in immune cells and resistance to innate defenses.