Interactions between Mycobacterium xenopi, amoeba and human cells

Outbreaks due to Mycobacterium xenopi have been linked with Mycobacterium contaminated water. M. xenopi has been shown to interact with the biofilm xenopi; Amoeba; formed in water distribution systems and to be hosted by free-living Nosocomial infection; Acanthamoeba. The present study investigated the interaction between Light M. xenopi and A. polyphaga amoeba, and between M. xenopi and human fibroblast HEL cells. Examination using the light microscopy together with electronic and confocal microscopy demonstrated that M. xenopi was located within the amoeba and in HEL cells. The Light Cycler measurement of the M. xenopi:A. polyphaga DNA ratio and the M. xenopi:HEL cell DNA ratio demonstrated intra-amoebal and intracellular growth of M. xenopi with doubling-times of five-days and 10 days, respectively. Intra-amoebal M. xenopi survived protozoan encystment and germination. These data demonstrate that M. xenopi is a facultative intra-amoebal and intracellular pathogen. Testing intra-amoebal M. xenopi might be necessary to property evaluate decontamination procedures for hospital water supply systems in order to achieve eradication. (c) 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.