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Characterization of clinical and environmental Mycobacterium avium spp. isolates and their interaction with human macrophages
Guirado, E., J. Arcos, R. Knaup, R. Reeder, B. Betz, C. Cotton, T. Patel, S. Pfaller, J. Torrelles, AND L. Schlesinger. Characterization of clinical and environmental Mycobacterium avium spp. isolates and their interaction with human macrophages. PLoS ONE . Public Library of Science, San Francisco, CA, 7(9):e45411, (2012).
The goal of this study was to develop a tool to measure the attachment, uptake and replication of M. avium clinical and environmental isolates in human macrophages.
Members of the Mycobacterium avium complex (MAC) are naturally occurring bacteria in the environment. A link has been suggested between M. avium strains in drinking water and clinical isolates from infected individuals. There is a need to develop new screening methodologies that can identify specific virulence properties of M. avium isolates found in water that predict a level of risk to exposed individuals. In this work we have characterized 15 clinical and environmental M. avium spp. isolates provided by the US Environmental Protection Agency (EPA) to improve our understanding of the key processes involved in the binding, uptake and survival of these isolates n primary human macrophages. M. avium serovar 8 was predominant among the isolates studied. Different amounts and exposure of mannose-capped lipoarabinomannan (ManLAM) and glycopeptidolipids (GPLs), both major mycobacterial virulence factors, were found among the isolates studied. Reference clinical isolate 104 serovar 1 and clinical isolates 11 and 14 serovar 8 showed an increased growth in primary human macrophages. The other isolates varied in their survival in these cells. Thus we conclude that the amounts of cell envelope ManLAM and GPL, as well as GPL serovar specificity are not the only important bacterial factors for dictating the early interactions of M. avium with human macrophages.