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Answer added in Protozoa18 How to differentiate alive Entamoeba histolytica from a dead one on a slide?Do a wet preparation from the stool sample in erythrosine stain and examine by light microscope. The dead amoebae will be stained red compared to the ... [more]
Publications (20) View all
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Article: Temperature Depended Role of Shigella flexneri Invasion Plasmid on the Interaction with Acanthamoeba castellanii.
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ABSTRACT: Shigella flexneri is a Gram-negative bacterium causing the diarrhoeal disease shigellosis in humans. The virulence genes required for invasion are clustered on a large 220 kb plasmid encoding type three secretion system (TTSS) apparatus and virulence factors such as adhesions and invasion plasmid antigens (Ipa). The bacterium is transmitted by contaminated food, water, or from person to person. Acanthamoebae are free-living amoebae (FLA) which are found in diverse environments and isolated from various water sources. Different bacteria interact differently with FLA since Francisella tularensis, Vibrio cholerae, Shigella sonnei, and S. dysenteriae are able to grow inside A. castellanii. In contrast, Pseudomonas aeruginosa induces both necrosis and apoptosis to kill A. castellanii. The aim of this study is to examine the role of invasion plasmid of S. flexneri on the interaction with A. castellanii at two different temperatures. A. castellanii in the absence or presence of wild type, IpaB mutant, or plasmid-cured strain S. flexneri was cultured at 30°C and 37°C and the interaction was analysed by viable count of both bacteria and amoebae, electron microscopy, flow cytometry, and statistical analysis. The outcome of the interaction was depended on the temperature since the growth of A. castellanii was inhibited at 30°C, and A. castellanii was killed by invasion plasmid mediated necrosis at 37°C.International Journal of Microbiology 01/2012; 2012:917031. -
Article: ToxR of Vibrio cholerae affects biofilm, rugosity and survival with Acanthamoeba castellanii.
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ABSTRACT: Vibrio cholerae causes the diarrheal disease cholera and utilizes different survival strategies in aquatic environments. V. cholerae can survive as free-living or in association with zooplankton and can build biofilm and rugose colonies. The bacterium expresses cholera toxin (CT) and toxin-coregulated pilus (TCP) as the main virulence factors. These factors are co-regulated by a transcriptional regulator ToxR, which modulates expression of outer membrane proteins (OmpU) and (OmpT). The aims of this study were to disclose the role of ToxR in expression of OmpU and OmpT, biofilm and rugose colony formation as well as in association with the free-living amoeba Acanthamoeba castellanii at different temperatures. The toxR mutant V. cholerae produced OmpT, significant biofilm and rugose colonies compared to the wild type that produced OmpU, decreased biofilm and did not form rugoes colonies at 30°C. Interestingly, neither the wild type nor toxR mutant strain could form rugose colonies in association with the amoebae. However, during the association with the amoebae it was observed that A. castellanii enhanced survival of V. cholerae wild type compared to toxR mutant strain at 37°C. ToxR does seem to play some regulatory role in the OmpT/OmpU expression shift, the changes in biofilm, rugosity and survival with A. castellanii, suggesting a new role for this regulatory protein in the environments.BMC Research Notes 01/2012; 5:33. -
Article: Detection of Vibrio cholerae and Acanthamoeba species from same natural water samples collected from different cholera endemic areas in Sudan.
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ABSTRACT: Vibrio cholerae O1 and V. cholerae O139 infect humans, causing the diarrheal and waterborne disease cholera, which is a worldwide health problem. V. cholerae and the free-living amoebae Acanthamoeba species are present in aquatic environments, including drinking water and it has shown that Acanthamoebae support bacterial growth and survival. Recently it has shown that Acanthamoeba species enhanced growth and survival of V. cholerae O1 and O139. Water samples from different cholera endemic areas in Sudan were collected with the aim to detect both V. cholerae and Acanthamoeba species from same natural water samples by polymerase chain reaction (PCR). For the first time both V. cholerae and Acanthamoeba species were detected in same natural water samples collected from different cholera endemic areas in Sudan. 89% of detected V. cholerae was found with Acanthamoeba in same water samples. The current findings disclose Acanthamoedae as a biological factor enhancing survival of V. cholerae in nature.BMC Research Notes 04/2011; 4:109. -
Article: Acanthamoeba-bacteria: a model to study host interaction with human pathogens.
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ABSTRACT: Acanthamoebae are free-living amoebae distributed worldwide. They are among the most prevalent protozoa found in the environment, and have been isolated from a wide variety of public water supplies, swimming pools, bottled water, ventilation ducts, soil, air, surgical instruments, contact lenses, dental treatment units and hospitals. Acanthamoebae feed on bacteria by phagocytosis, but some bacteria are able to survive and sometimes multiply in the host, resulting in new properties of the bacteria. The intracellular growth of bacteria has been associated with enhanced environmental survival of the bacteria, increased virulence and increased resistance against antibiotic substances. The advantage of utilising free-living amoebae is that research can be carried out on non-mammalian cells as a model based on natural reality to study bacterial virulence and pathogenicity. Amoebae are easy to handle experimentally compared with mammalian cells and allow studies on host factors for host-parasite interactions. Bacteria are easily manipulated genetically, which creates the possibility of research on mutants to study bacteria-host interactions. Thus utilising this non-mammalian model can result in better understanding of interactions between prokaryotic and eukaryotic cells and assist in the development of new therapeutic agents to recognise and treat infections.Current drug targets 03/2011; 12(7):936-41. · 3.93 Impact Factor -
Article: Significant Association of Streptococcus bovis with Malignant Gastrointestinal Diseases.
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ABSTRACT: Streptococcus bovis is a Gram-positive bacterium causing serious human infections, including endocarditis and bacteremia, and is usually associated with underlying disease. The aims of the current study were to compare prevalence of the bacterium associated with malignant and nonmalignant gastrointestinal diseases and to determine the susceptibility of the isolated strains to different antimicrobial agents. The result showed that the prevalence of S. bovis in stool specimens from patients with malignant or with nonmalignant gastrointestinal diseases was statistically significant. This result may support the idea that there is correlation between S. bovis and the malignant gastrointestinal diseases.International Journal of Microbiology 01/2011; 2011:792019.
