Survival of Environmental Mycobacteria in Acanthamoeba polyphaga

Abstract

Free-living amoebae in water are hosts to many bacterial species living in such an environment. Such an association enables bacteria to select virulence factors and survive in adverse conditions. Waterborne mycobacteria (WBM) are important sources of community-and hospital-acquired outbreaks of nontuberculosis mycobacterial infections. However, the interactions between WBM and free-living amoebae in water have been demonstrated for only few Mycobacterium spp. We investigated the ability of a number (n ‫؍‬ 26) of Mycobacterium spp. to survive in the trophozoites and cysts of Acanthamoeba polyphaga. All the species tested entered the trophozoites of A. polyphaga and survived at this location over a period of 5 days. Moreover, all Mycobacterium spp. survived inside cysts for a period of 15 days. Intracellular Mycobacterium spp. within amoeba cysts survived when exposed to free chlorine (15 mg/liter) for 24 h. These data document the interactions between free-living amoebae and the majority of waterborne Mycobacterium spp. Further studies are required to examine the effects of various germicidal agents on the survival of WBM in an aquatic environment.Mycobacteria are a large group of microorganisms that inhabit a diverse range of natural environments. Environmental mycobacteria are a frequent cause of opportunistic infection in human beings and livestock (23,56,76). There is growing recognition in recent years that water is an important vehicle of transmission of environmental mycobacteria. This is based on the fact that in the recent past contaminated water supply systems have been responsible for several hospital and community outbreaks of mycobacterial infections (16,77,78,79,82,83). These included infections as diverse as life-threatening pneumonia in patients with artificial ventilation, cystic fibrosis (54), and chronic granulomatous disease (79); outbreaks of skin infection following liposuction (51); furunculosis after domestic footbaths (77, 83); mastitis after body piercing (73); and abscess formation in intravenous drug users (26). In one instance (79, 82), workers exposed to contaminated industrial effluents developed pneumonia due to an environmental mycobacterium.In hospital therapy pools, waterborne mycobacteria (WBM) may represent about 33% of the microorganisms present in water and about 80% of those in air in the vicinity of such a contaminated water source (5). WBM include both rapidly and slowly growing Mycobacterium spp., depending on whether they require a week or less for the production of visible colonies in solid medium. Examples of WBM include among other species the Mycobacterium avium complex, Mycobacterium gordonae, Mycobacterium malmoense, Mycobacterium simiae, Mycobacterium marinum, Mycobacterium tusciae, and Mycobacterium lentiflavum, which have been found in natural fresh waters (72,76) . Mycobacterium mucogenicum, Mycobacterium kansasii, M. gordonae, Mycobacterium flavescens, Mycobacterium aurum, Mycobacterium fortuitum, Mycobacterium peregrinum, andMycobacterium chelonae have been ...

EmergingMycobacteriaspp. in Cooling Towers

“…The 33 isolates corresponded to 5 mycobacterial species: M. fortuitum, M. conceptionense, M. chelonae, M. chimaera, and M. phocaicum (Table). Some of these mycobacteria already had been shown to survive in freeliving amebae and to be implicated in human diseases, such as M. chelonae (5). The same author demonstrated recently that 26 environmental mycobacteria survived in the trophozoites and cysts of Acanthamoeba polyphaga (5).…”

“…In 2003, cooling towers were reported to be a potential source of slow-growing mycobacterial species (1). Some mycobacterial species recently were shown to survive within amebae (5). We aimed to study the population of ameba-associated mycobacterial species in 3 cooling towers using a co-coculture method.…”

Burkholderia bacteria infectiously induce the proto-farming symbiosis of Dictyostelium amoebae and food bacteria

“…In addition, certain isolates of the soil-dwelling amoeba Dictyostelium discoideum persistently associate with bacteria, an association that has beneficial or detrimental outcomes depending on the environmental conditions (23)(24)(25). Amoebas can serve as environmental reservoirs for bacterial pathogens (26,27) or as training facilities for the adaptation of bacteria to evade eukaryotic phagocytosis or to survive intracellularly after phagocytosis (17,28). Although, for the eukaryotic host, some of these interactions may have decidedly unfortunate outcomes, such as the emergence of bacterial pathogenesis through intracellular adaptation, others may illuminate important evolutionary advances, such as the transition of bacterial endosymbionts into organelles that provide novel functionality.…”

Pyrosequencing analysis of eukaryotic and bacterial communities in faucet biofilms

“…It has also been reported that Mycobacterium spp. can enter and survive in the trophozoites and cysts of Acanthamoeba polyphaga (Adekambi et al, 2006). Therefore, investigation for eukaryotic communities is necessary to better understand the microbial ecology and potential health risk associated with pathogens in DWDSs.…”