Browsing by Subject "Drug resistance in microorganisms"
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Item Antibiotic resistance of pathogenic bacteria in playa lakes(Texas Tech University, 1998-12) Warren, William JohnNot availableItem Antibiotic- and metal-resistantö öAöeörööoömöoönöaös isolated from environmental sources(Texas Tech University, 2003-05) Huddleston, Jennifer R.Aeromonas is a ubiquitous aquatic bacterium that causes serious infections in both cold- and warm-blooded animals, including humans. Clinical isolates of the organism have shown an increasing incidence of antibiotic and antimicrobial drug resistances since the widespread use of antibiotics began. The genes for antibiotic resistance and metal resistance are frequently carried on the same plasmids, imparting both characteristics to the host bacterium. When there are either antibiotics or metals present in the environment, both markers are co-selected. Two hundred eighty-three Aeromonas isolates belonging to eleven different species were isolated from several streams and both urban and rural playa lakes in Lubbock, TX and New Mexico. The minimal inhibitory concentrations of seven metals, six antibiotics, and two synthetic drugs were determined. Low incidences of trimethoprim resistance, mercury resistance, and arsenite resistance were found. Antibiotic and metal resistances were not linked in almost all of the Aeromonas isolates. Plasmids were isolated from selected strains of the arsenite- and mercury-resistant organisms and transformed into Escherichia coli XLl-Blue MRP', showing that the resistance genes were carried on plasmids. From the data, it was concluded that mercury and arsenite resistance could be transferred to other organisms in natural environments.Item Expression of three efflux pumps(Texas Tech University, 2002-12) Wheeler, David MichaelDrug efflux is a major mechanism of resistance to drugs in both cancer cells and pathogenic microorganisms. Consequently, there is an urgent need to understand the structure, function, and expression of the multidrug resistance pumps involved so that inhibitors can be designed to block drug extrusion. One of the most frequently employed resistance strategies in both prokaryotes and eukaryotes is the use of protein efflux pumps, reducing the intracellular drug concentration to sub-toxic levels. The plant signaling molecule salicylate has been shown to increase levels of resistance for several antibiotics and induce expression of multiple genes involved in antibiotic resistance. In this study using Erwinia chrysanthemi 3937 DE, salicylate increased antibiotic resistance of novobiocin and naladixic acid but had no affect on the detergents deoxycholate and sodium dodecyl sulfate resistance levels. Northern hybridization revealed that deoxycholate, sodium dodecyl sulfate, and salicylate increased emr, acr, yceE, and tolC expression while showing no increase for the antibiotics novobiocin and naladixic acid. This represents the first time efflux pump expression and native antibiotic resistance levels have been observed in E. chrysanthemi. This data will help in the further research of efflux pumps and their involvement in plant pathogenesis of E. chrysanthemi.Item Fate and effect of amoxicillin in space and terrestrial water reclamation systems(Texas Tech University, 2003-05) Morse, AudraAs NASA strives towards long-term manned space travel, wastewater recycling will be necessary to provide adequate water. Contaminants, including pharmaceuticals, may be present if astronauts take medications. The overall effects of pharmaceuticals, specifically antibiotics, in recycled wastewater are unknown. One concern is the development of antibiotic resistance by pathogenic bacteria. Additionally, the effects of antibiotics on biological wastewater recycling systems have not been quantified. The overall objective of this research was to determine the fate of amoxicillin in wastewater reclamation systems. Wastewater recycling systems investigated included both systems and feeds typical of space applications located at Johnson Space Center (JSC) and Texas Tech University (TTU), as well as one terrestrial wastewater recycling system (City of Lubbock's Water Reclamation Plant). The overall objective of this research was further divided into three sub-objectives to determine (1) the fate of amoxicillin in JSC's and TTU's water recovery system; (2) the effects of amoxicillin on treatment efficiency; and (3) the development of antibiotic resistance by the microorganisms in the treatment system. The results of this study indicate amoxicillin is easily removed in a biological wastewater treatment system. In addition, the post-processing units were capable of removing amoxicillin. Due to the low concentrations of amoxicillin in the JSC-WRS and TTU-WRS, amoxicillin did not affect the treatment efficiency of the system although if concentrations increased above 10 mg/L some inhibition may be possible. Organisms in all systems were resistant to the antibiotics investigated, including many beta-lactam antibiotics and a beta-lactam, beta-lactamase inhibitor combination (amoxicillin with clavulanic acid). In both systems, resistance was present in the system before initiating the amoxicillin experiment. The antibiotic resistance patterns of the LWRP varied monthly; heterotrophic bacteria were resistant to most of the antibiotics investigated during the nine month study. In summary, amoxicillin will not accumulate in biological wastewater treatment systems and treatment efficiency will be unaffected by amoxicillin presence; however, microorganism may develop a resistant to amoxicillin if they are not already resistant to amoxicillin.Item Genetic characterization of an Escherichia coli plasmid associated with hydrogen sulfide production and drug resistance(Texas Tech University, 1977-05) Thai, Le PhamNot availableItem The role of the metal ion in the catalytic cycle of beta-lactamase II(Texas Tech University, 1993-05) Myers, J. LynnWith beta-lactam antibiotics being the most widely used antibacterial agents in clinical use In the world today, mechanistic studies of these enzymes, called betalactamases, which are responsible for beta-lactam antibiotic resistance in pathogenic bacteria have become Increasingly Important. Mechanistic studies have enabled researchers to develop a suicide or mechanism-based inhibitor, known commercially as Augmentin, which inactivates beta-lactamase I, a class A enzyme. Currently, there are no known inhibitors of beta-lactamase II, a class B enzyme.