title: Acanthamoeba polyphaga-enhanced growth of Mycobacterium smegmatis.
abstract: BACKGROUND
  Mycobacterium smegmatis is a rapidly-growing mycobacterium causing rare opportunistic infections in human patients. It is present in soil and water environments where free-living amoeba also reside, but data regarding M. smegmatis-amoeba relationships have been contradictory from mycobacteria destruction to mycobacteria survival.
  
  
  RESULTS
  Using optic and electron microscopy and culture-based microbial enumeration we investigated the ability of M. smegmatis mc(2) 155, M. smegmatis ATCC 19420(T) and M. smegmatis ATCC 27204 organisms to survive into Acanthamoeba polyphaga trophozoites and cysts. We observed that M. smegmatis mycobacteria penetrated and survived in A. polyphaga trophozoites over five-day co-culture resulting in amoeba lysis and the release of viable M. smegmatis mycobacteria without amoebal cyst formation. We further observed that amoeba-co-culture, and lysed amoeba and supernatant and pellet, significantly increased five-day growth of the three tested M. smegmatis strains, including a four-fold increase in intra-amoebal growth.
  
  
  CONCLUSIONS
  Amoebal co-culture increases the growth of M. smegmatis resulting in amoeba killing by replicating M. smegmatis mycobacteria. This amoeba-M. smegmatis co-culture system illustrates an unusual paradigm in the mycobacteria-amoeba interactions as mycobacteria have been mainly regarded as amoeba-resistant organisms. Using these model organisms, this co-culture system could be used as a simple and rapid model to probe mycobacterial factors implicated in the intracellular growth of mycobacteria.
authors.affiliation: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UMR CNRS 6236 IRD 3R198, IFR48, Méditerranée Infection, Aix-Marseille Université, Marseille, France.
authors.forename: Otmane
authors.initials: O
authors.lastname: Lamrabet
authors.forename: Felix
authors.initials: F
authors.lastname: Mba Medie
authors.forename: Michel
authors.initials: M
authors.lastname: Drancourt
mesh_terms: D000048:Acanthamoeba / Q000166:cytology / Q000382:microbiology* / Q000648:ultrastructure; D018920:Coculture Techniques; D004705:Endocytosis; D006790:Host-Parasite Interactions; D006801:Humans; D008954:Models, Biological; D009164:Mycobacterium Infections / Q000382:microbiology; D020102:Mycobacterium smegmatis / Q000254:growth & development* / Q000648:ultrastructure; D053058:Trophozoites / Q000166:cytology / Q000382:microbiology / Q000648:ultrastructure