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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/4038

Title: The role of free-living amoebae as reservoir in the transmission of Mycobacterium Ulcerans
Authors: Amissah, Diana Ackon
Issue Date: 19-Jun-2011
Abstract: Mycobacterium ulcerans causes Buruli ulcer disease. The bacterium can be found predominantly in swamps and slow-flowing water areas. Understanding the ecology of M. ulcerans has been severely hampered due to a knowledge gap of the reservoir and precise mode of transmission although aquatic insects and mosquitoes have been implicated in its transmission. Free-living amoebae (FLA) are common inhabitants of the aquatic ecosystems and have been shown to be naturally infected with environmental mycobacteria that may cause human infections. This study investigated the hypothesis that FLA could serve as reservoirs of M. ulcerans and aid in its transmission to humans. Five hundred and thirty nine environmental specimens were collected from water bodies in five endemic and two non endemic communities for ten months; 13 aerosols, 223 biofilms from plant, 205 biofilms from trunks, 45 detritus, 53 water filtrates from five endemic and two non endemic communities. FLA were isolated from 369 (68.5%) environmental specimens and three genera were identified by PCR; Acanthamoeba 157 (29.1%), Vahlkamfiidae 306 (56.8%) and Naegleria 118 (21.9%). The effect of pH, temperature and bacterial load on the isolation of amoebae were investigated. While isolation of Vahlkampfiidae was independent of physical parameters (pH and temperature), an increase in these parameters increased the isolation Naegleria and Acanthamoeba species. FLA were not dependent on bacterial load specifically E. coli as source of nutrient since they may have had alternative sources (yeast, fungi and other protozoa) for food. One hundred and thirty one intracellular mycobacteria were isolated and identified. Intracellular mycobacteria were often isolated from specimens positive for isolation of amoebae and positive for 16S rDNA PCR from amoebae cultures. Culture of M. ulcerans from FLA and environmental specimens was attempted. One isolate was positive for IS2404 PCR but negative upon confirmation by Variable-Number Tandem Repeat typing. M. ulcerans DNA was detected from a water filtrate and IS2404 target was detected from 2 environmental specimens and 25 amoebae cultures. The study showed no association between M. ulcerans and FLA, however, results indicated a significant association between FLA (Acanthamoeba and Vahlkampfiidae genera) and IS2404 target. These data may have implications for the reservoir and transmission of environmental mycobacteria that habour IS2404 target. These findings may provide important information for understanding the ecology of M. ulcerans.
Description: A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Philosophy, 2011
URI: http://hdl.handle.net/123456789/4038
Appears in Collections:College of Health Sciences

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