Acanthamoeba: Could it be an environmental host of Shigella?

Jeong, Hoon Eui; Jang, Eun Seong; Han, Byung In; Lee, Keun Hee; Ock, Mee Sun; Kong, Hyun-Hee; Chung, Dong Il; Seol, Sung Yong; Cho, Dong Taek; Yu, Hak Sun

doi:10.1016/j.exppara.2006.08.002

Cited by 38 publications

(27 citation statements)

References 18 publications

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“…With this information, we may only assume that T4 and T7 genotypes are represented in the Tenerife environmental samples. Data from countries such as Brazil (Magliano et al 2009), France (Thomas et al 2008), Switzerland (Gianinazzi et al 2009), South Korea (Jeong et al 2007), and USA (Booton et al 2004) have provided supporting evidence for that. However, in Osaka (Japan) (Hsu et al 2009), the most frequent genotype was T3 (56.8%) and T4 (13.5%); and in Taiwan (Edagawa et al 2009), A. griffini (T3) was the most frequent followed by Acanthamoeba jacobsi (T15).…”

Section: Discussionmentioning

confidence: 77%

Molecular characterization of Acanthamoeba isolated in water treatment plants and comparison with clinical isolates

et al. 2012

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A total of 116 samples (44 clinical specimens and 72 environmental samples) have been analyzed for the presence of Acanthamoeba. The environmental samples (ESs) were collected from four drinking water treatment plants (DWTP, n=32), seven wastewater treatment plants (n=28), and six locations of influence (n=12) on four river basins from the central area of Spain (winter-spring 2008). Water samples were concentrated by using the IDEXX Filta-Max(®) system. Acanthamoeba was identified in 65 of the 72 ESs by culture isolation (90.3%) and 63 by real-time PCR (87.5%), resulting in all sampling points (100%) positive for Acanthamoeba when considering both techniques and all the time period analyzed. Nine of the 44 clinical specimens were positive for Acanthamoeba. Seventeen Acanthamoeba strains (eight from four DWTP and nine from clinical samples) were also established in axenic-PYG medium. Twenty-four of the ESs and the 17 Acanthamoeba sp. strains were genotyped as T4/1, T4/8, and T4/9. The eight strains isolated from the DWTP samples were inoculated in nude mouse to ascertain their potential pathogenicity in this model. Animals that were inoculated died or showed central nervous system symptoms 9 days post-inoculation. Examination of immunofluorescence-stained brain and lung tissue sections showed multiple organisms invading both tissues, and re-isolation of throphozoites was successful in these tissues of all infected animals. For the first time, potentially pathogenic Acanthamoeba T4 has been detected in 100% of different types of water samples including tap water and sewage effluents in the central area of Spain suggesting a potential health threat for humans especially for the contact lens wearers.

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Section: Discussionmentioning

confidence: 77%

Molecular characterization of Acanthamoeba isolated in water treatment plants and comparison with clinical isolates

et al. 2012

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“…S. Typhi is not known to persist in the environment, and it was previously demonstrated that S. Typhi strains were extremely sensitive to chlorinated water (38). As amoebae were associated with increased survival and persistence in the environment for many bacterial pathogens, such as Shigella, Legionella, Vibrio, and Salmonella (2,12,17,18,24), the association between A. castellanii and S. Typhi was investigated.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, the interaction with free-living protozoa is also associated with increased survival and persistence in the environment (26) and with increased virulence (8,31,35). Thus, there is increasing evidence that complex relationships exist between environmental free-living protozoa and intracellular pathogens such as Legionella, Chlamydia, Mycobacterium, and Shigella (5,24,32,39). Salmonella enterica serovar Typhimurium was shown to replicate and survive in Acanthamoeba spp.…”

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confidence: 99%

Increased Persistence of Salmonella enterica Serovar Typhi in the Presence of Acanthamoeba castellanii

Douesnard-Malo

2011

Appl Environ Microbiol

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Salmonella enterica serovar Typhi (S. Typhi) is the etiological agent of the systemic disease typhoid fever. Transmission occurs via ingestion of contaminated food or water. S. Typhi is specific to humans, and no animal or environmental reservoirs are known. As the free-living amoeba Acanthamoeba castellanii is an environmental host for many pathogenic bacteria, this study investigates interactions between S. Typhi and A. castellanii by using cocultures. Growth of both organisms was estimated by cell count, viable count, flow cytometry, and fluorescence microscopy. Results indicate that S. Typhi can survive at least 3 weeks when grown with A. castellanii, as opposed to less than 10 days when grown as singly cultured bacteria under the same conditions. Interestingly, growth rates of amoebae after 14 days were similar in cocultures or when amoebae were singly cultured, suggesting that S. Typhi is not cytotoxic to A. castellanii. Bacteria surviving in coculture were not intracellular and did not require a physical contact with amoebae for their survival. These results suggest that S. Typhi may have a selective advantage when it is associated with A. castellanii and that amoebae may contribute to S. Typhi persistence in the environment.

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“…Cocultures were monitored visually every day; at various time points, the total number of amoebae was determined by first disrupting each well by vigorous pipetting and counting aliquots with a hemocytometer. The ratio of live to dead amoebae was determined by staining aliquots of the coculture with trypan blue for 10 min (18). At each time point, the number of extracellular bacteria was enumerated by plating serial dilutions on minimal marine medium or MLB supplemented with 0.1% sodium pyruvate (V. parahaemolyticus) or LB (E. coli) as appropriate.…”

Section: Methodsmentioning

confidence: 99%

Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus

Laskowski-Arce

Orth

2008

Appl Environ Microbiol

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Vibrio parahaemolyticus is a food-borne pathogen that naturally inhabits both marine and estuarine environments. Free-living protozoa exist in similar aquatic environments and function to control bacterial numbers by grazing on free-living bacteria. Protozoa also play an important role in the survival and spread of some pathogenic species of bacteria. We investigated the interaction between the protozoan Acanthamoeba castellanii and the bacterium Vibrio parahaemolyticus. We found that Acanthamoeba castellanii does not prey on Vibrio parahaemolyticus but instead secretes a factor that promotes the survival of Vibrio parahaemolyticus in coculture. These studies suggest that protozoa may provide a survival advantage to an extracellular pathogen in the environment.Vibrio parahaemolyticus is a gram-negative, incidental pathogen that causes food-borne gastroenteritis, septicemia, and wound infections. The most common source of infection is contact with undercooked or raw seafood, particularly oysters (9). The pathogenicity of V. parahaemolyticus has been attributed to multiple virulence factors, of which the most well studied are the thermostable direct hemolysin (TDH) and the similar TDH-related hemolysin (TRH) (42). These hemolysins are found in most clinical strains and have been associated with cytotoxicity, enterotoxicity, cardiotoxicity, and hemolytic activity (39,42,44). V. parahaemolyticus also possesses two distinct type III secretion systems (T3SS), which allow for the direct translocation of bacterial proteins into host cells (26). Bacteria use these translocated proteins, known as effectors, to manipulate the host to promote bacterial survival and/or virulence (13). Although the precise role that each T3SS plays in V. parahaemolyticus pathogenesis is not understood, it has been shown that the T3SS encoded on the large chromosome (T3SS1) contributes to cytotoxicity toward eukaryotic cells and that the T3SS encoded on the smaller chromosome (T3SS2) is responsible for enterotoxicity (7,35,36).V. parahaemolyticus is commonly isolated from many environmental sources, including marine, estuarine, and coastal waters (20,21). The prevalence of V. parahaemolyticus in the environment and incidence of infection have been linked to rising water temperatures caused by global warming (32). V. parahaemolyticus has been found to be associated with various plankton, copepods, and crustaceans; however, sampling from various coastal sites reveals that V. parahaemolyticus is present in sediment, as well as free-living in water (5,8,(19)(20)(21). In fact, the number of V. parahaemolyticus organisms detected in water samples is greater than or equal to the number associated with plankton, supporting the proposal that free-living bacteria contain a large population of V. parahaemolyticus in the environment (5, 20).In the environment, free-living bacteria coexist with protozoa. The interaction between these organisms is complex and can be parasitic, commensal, or mutualistic in nature. Acanthamoeba castellanii is a unicellular fr...

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Acanthamoeba: Could it be an environmental host of Shigella?

Cited by 38 publications

References 18 publications

Molecular characterization of Acanthamoeba isolated in water treatment plants and comparison with clinical isolates

Molecular characterization of Acanthamoeba isolated in water treatment plants and comparison with clinical isolates

Increased Persistence of Salmonella enterica Serovar Typhi in the Presence of Acanthamoeba castellanii

Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus

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