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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Environmental Isolation of Cryptococcus species and Tricosporon asahii in Southern Taiwan

Lee, Chih-kung 10 January 2012 (has links)
The increasing infection of Cryptococcus species and Tricosporon asahii emerged in clinical patients who were immunocompromised. They usually induce lung, skin, brain and systemic infection. Morbidity and mortality of immunocompromised patients are higher than normal healthy people. Cryptococcus neoformans var. grubii ¡]serotype A¡^ infections were reported in clinical cases predominantly and they were isolated from birds¡¦ droppings in large amount. Cryptococcus neoformans var. gattii ¡]serotype B, C¡^ had a natural life in plants, especially Eucalypticus trees. Isolations from other trees were reported increasingly in the tropical and subtropical areas. Comparing to Cryptococcus species, Tricosporon asahii is the normal mycoses of soil. In this study, we performed an environmental investigation concerning Cryptococcus species and Tricosporon asahii in Southern Taiwan. 120 droppings of racing pigeons and 114 samples from Eucalypticus trees were obtained. The results revealed that 30 Cryptococcus neoformans were isolated from racing pigeons¡¦ droppings ¡]25%¡^, as well as 4 Cryptococcus laurentii ¡]3.3%¡^ and 2 Cryptococcus albidus ¡]1.7%¡^. In addition, 25 Tricosporon asahii ( 20.8% ) were isolated from droppings of racing pigeons. But, none of Cryptococcus species or Tricosporon asahii is isolated from Eucalypticus trees ¡]0%¡^. All of Cryptococcus neoformans isolated from pigeons¡¦ droppings were var. grubii ¡]serotype A¡^ and their drug susceptibility tests showed sensitive to Amphotericin B ¡]minimal inhibitory concentration ¡Ø0.25£gg/ml¡^ and Fluconazole ¡]minimal inhibitory concentration 2£gg/ml¡^ and Flucytosine ¡]minimal inhibitory concentration ¡Ø1£gg/ml¡^. To sum up, both Cryptococcus species and Tricosporon asahii were isolated from droppings of racing pigeons in our study, especially Tricosporon asahii in large amount. Opportunistic infection caused by these species should be given more attention to racing pigeons which have close contact with human . Intensive investigation and surveillance should be carried out in the future to provide an information for the control and prevention of diseases.
2

Characterization and identification of microbial communities in pigeon droppings using Culture-Independent techniques

Leareng, Samuel Keeng 08 1900 (has links)
M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Science), Vaal University of Technology| / Pigeon droppings, found in abundance in most cities and towns where pigeons are found, are a source of potential yeast and molds into the environment. Invasive fungal infections are a cause of morbidity and often mortality in immunocompromised individuals. The objective of this study was to the identification of bacterial and mold agents from pigeon droppings. Pigeon droppings samples were collected from three locations during the winter and summer months and studied for the occurrence of bacteria, yeast and molds by utilising culture-independent techniques. Amplification of the 16S rDNA gene and the internal transcribed spacer (ITS) region, cloning and ARDRA and DGGE were used for the characterisation of the microbial populations followed by sequencing. Several mold and yeasts, as well as bacteria were found to be present in pigeon droppings, which can spread into the environment and be transmitted to immunocompromised individuals and children. DGGE analysis of the bacterial communities revealed banding patterns that clustered all but one winter samples and all summer samples, showing a high similarity among the microbial members in both seasons and sample locations. Fungal DGGE analysis revealed clusters that grouped summer and winter samples from Johannesburg and Pretoria while VUT samples were clustered on their own. From the identification of fungal and bacterial DNA, Cryptococcus species was the majority of fungi isolated from the dropping samples. Geotrichum, Kazachstania and Fusarium species were isolated from phylotypes obtained from ITS amplicons analysed by ARDRA. Lactobacillus and Enteroccoccus species, organisms usually found in the gastrointestinal tract were the common bacterial members identified. The results showed no difference in microbial communities across all sample locations, while seasonal changes also had no impact in microbial community patterns.

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