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Moraxella (Branhamella) Catarrhalis: A Molecular Epidemiology Study, Lyndell R. Gill

Electronic Theses and Dissertations

Moraxella (Branhamella) catarrhalis is the third-most-frequently isolated microorganism associated with acute exacerbations of chronic bronchitis in patients during their stay at the Mountain Home VA Medical Center (MHVAMC). In order to develop a practical, epidemiologically-meaningful typing method for M. (B.) catarrhalis, we tested two methods based on analysis of chromosomal DNA for typeability, reproducibility, and ability to differentiate between unrelated strains (discriminatory power, D). M. (B.) catarrhalis isolants from MHVAMC from 7/1/87-6/30/88 were grown overnight in broth and embedded in agarose. DNA was isolated by standard methods. The DNA was subjected to: (1) restriction endonuclease digestion (with either Bgl II …

Comparison Of Chlorine And Chlorine Dioxide As Disinfectants For Surface Waters, Kristen S. Tilton

Doctoral Dissertations

Safe supplies of drinking water free of pathogenic agents such as viruses and protozoa are essential for humankind. The evaluation of current treatment practices for the removal of pathogens has become increasingly important with the occurrence of waterborne disease outbreaks. Shortcomings associated with chlorine have prompted the need to assess alternative disinfectants.

The overall objective of this research is to compare chlorine and chlorine dioxide as disinfectants for surface waters using Giardia muris cysts, bacteriophage MS2, total and fecal coliforms, and heterotrophic bacteria. Concentration x time (CT) values for the inactivation of Giardia muris cysts and MS2 bacteriophage as a …

Characterization Of The Adherence Mechanisms Of Listeria Monocytogenes To Host Cells And Their Role In The Pathogenesis Of Listeriosis, Marcia M. Pierce

Doctoral Dissertations

Listeria monocytogenes is the facultative intracellular pathogen responsible for causing the foodborne illness known as listeriosis. Disease occurs following invasion of cells of the intestinal tract by the organism following consumption of contaminated foods. In this study, a mechanism of opsonin-independent attachment of L. monocytogenes to host cells was identified. A clinical isolate of L. monocytogenes, together with murine-derived primary peritoneal macrophages were used to study this adherence phenomenon.

Transmission and scanning electron microscopy were used to visualize the attachment and uptake of L. monocytogenes by murine macrophages, while organism enumeration by viable bacterial cell colony counts was used as …

Biochemical And Microbiological Characteristics Of Ground Beef In Modified Atmosphere Packaging With Gas Exchange., Chung-Ping Ho

LSU Historical Dissertations and Theses

The shelf-life of ground beef in modified atmosphere packaging (MAP) with exchange of gases before retail display was compared with conventional vacuum packaging (VP) and overwrapping with polyvinylchloride film (PVC) for display. Ground beef patties in MAP with distribution gases of 20% $\rm N\sb2:80\%\ CO\sb2,\ 50\%\ N\sb2:50\%\ CO\sb2,\ or\ 80\%\ N\sb2:20\%\ CO\sb2$ and display gases of 80% $\rm O\sb2:20\%\ CO\sb2,\ 50\%\ O\sb2:20\%\ CO\sb2:30\%\ N\sb2,$ or 20% $\rm O\sb2:20\%\ CO\sb2:60\%\ N\sb2$ had decreased weight loss, microorganism growth rate, metmyoglobin formation, and color degradation compared with patties in VP-PVC. Increased CO$\sb2$ during distribution retarded microbial growth. Display gas mixtures with higher O$\sb2$ …

Differentiation Of Tobacco Etch Virus Strains Affecting Pepper., Indra Ariyaratne

LSU Historical Dissertations and Theses

Tobacco etch virus (TEV) causes an important viral disease of pepper (Capsicum spp.) in the Western Hemisphere. In this study, 36 isolates of TEV from the United States, Mexico, the Caribbean, Central America, and South America were mechanically inoculated in the greenhouse to selected pepper lines reported to have resistance to one or more TEV isolates. Goals of the research were to evaluate reactions of the resistant pepper lines to the TEV isolates, and to determine if the TEV isolates could be grouped into pathotypes based on their reactions in pepper lines chosen as differentials during the course of the …

The In Vitro Studies On Phage Mu Transposase, Zhenguo Wu

Digitized Theses

Bacteriophage Mu is one of the model systems to study DNA transposition. The availability of an in vitro soluble system greatly facilitates the dissection of the transposition mechanisms at the molecular levels. Several aspects of the in vitro mini-Mu DNA transposition have been dealt with in this thesis.;First, the flanking host DNA sequences on the strand cleavage step mediated by Mu transposase (Mu A protein) was investigated. We found that certain flanking host sequences could inhibit the strand cleavage step without affecting the earlier synapsis step. Furthermore, this cleavage defect could be overcome by the Mu B protein in the …