Zugl.: Hannover, Tierärztliche Hochsch., Diss., 2005

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 160-170). Also available via the Internet.

El presente estudio se realizó con la finalidad de caracterizar cepas clínicas de Listeria monocytogenes aisladas en el Hospital San Bartolomé de Lima- Perú durante los años 2001 a 2005. Durante el periodo del estudio, se identificaron 18 casos de listeriosis perinatal, de los cuales fueron aisladas 20 cepas de L. monocytogenes. Las cepas fueron caracterizadas mediante pruebas convencionales y técnicas de biología molecular. Las 20 cepas en estudio fueron identificadas mediante las características fenotípicas conocidas de L. monocytogenes, tales como presencia de β-hemólisis incompleta, reacción de Christhie, Atkins y Munch-Peterson positiva con S. aureus y negativa con R. equi, así como la utilización de carbohidratos como D-glucosa y L-ramnosa, pero no de D-xilosa ni D-manitol. Todas las cepas fueron confirmadas mediante la reacción en cadena de la polimerasa y tipificadas por la técnica del ADN polimórfico amplificado al azar (RAPD). Con los cebadores OMP-01 y PJ108 se obtuvieron 6 RAPD tipos, distribuidas así: ocho cepas del tipo A-I, tres de cada uno de los tipos A-II, A-III y B-II, dos del tipo B-I y una del tipo A-IV. Se concluye que, en los 18 casos de listeriosis se obtuvieron 20 cepas de L. monocytogenes con seis genotipos diferentes, siendo el RAPD tipo A-I el más frecuente (8/20, 40%) entre las cepas estudiadas. / --- This study was conducted in order to characterize strains of Listeria monocytogenes isolates from the San Bartolome´s Hospital in Lima-Peru during the years from 2001 to 2005. During the study period, we identified 18 cases of perinatal listeriosis, which were isolated 20 strains of L. monocytogenes. The strains were characterized by conventional tests and molecular biology techniques. The 20 strains studied were identified by known phenotypic characteristics of L. monocytogenes, such as the presence of incomplete β-hemolysis, positive CAMP reaction with S. aureus and negative CAMP reaction with R. equi, and the use of carbohydrates as D-glucose and L-rhamnose but not from D-xylose or D-mannitol. The strains of L. monocytogenes were confirmed by polymerase chain reaction and typed by random amplified polymorphic DNA (RAPD) technique. With the primers OMP-01 and PJ108 were obtained six RAPD types, distributed as follows: eight strains of type AI, three of each type A-II, A-III and B-II, two type B-I and one strain of type A-IV. We conclude that, in 18 cases of listeriosis were obtained 20 strains of L. monocytogenes with six different genotypes, RAPD type A-I being the most frequent (8/20, 40%) among the studied strains. / Tesis

El presente estudio se realizó con la finalidad de caracterizar cepas clínicas de Listeria monocytogenes aisladas en el Hospital San Bartolomé de Lima- Perú durante los años 2001 a 2005. Durante el periodo del estudio, se identificaron 18 casos de listeriosis perinatal, de los cuales fueron aisladas 20 cepas de L. monocytogenes. Las cepas fueron caracterizadas mediante pruebas convencionales y técnicas de biología molecular. Las 20 cepas en estudio fueron identificadas mediante las características fenotípicas conocidas de L. monocytogenes, tales como presencia de β-hemólisis incompleta, reacción de Christhie, Atkins y Munch-Peterson positiva con S. aureus y negativa con R. equi, así como la utilización de carbohidratos como D-glucosa y L-ramnosa, pero no de D-xilosa ni D-manitol. Todas las cepas fueron confirmadas mediante la reacción en cadena de la polimerasa y tipificadas por la técnica del ADN polimórfico amplificado al azar (RAPD). Con los cebadores OMP-01 y PJ108 se obtuvieron 6 RAPD tipos, distribuidas así: ocho cepas del tipo A-I, tres de cada uno de los tipos A-II, A-III y B-II, dos del tipo B-I y una del tipo A-IV. Se concluye que, en los 18 casos de listeriosis se obtuvieron 20 cepas de L. monocytogenes con seis genotipos diferentes, siendo el RAPD tipo A-I el más frecuente (8/20, 40%) entre las cepas estudiadas. / This study was conducted in order to characterize strains of Listeria monocytogenes isolates from the San Bartolome´s Hospital in Lima-Peru during the years from 2001 to 2005. During the study period, we identified 18 cases of perinatal listeriosis, which were isolated 20 strains of L. monocytogenes. The strains were characterized by conventional tests and molecular biology techniques. The 20 strains studied were identified by known phenotypic characteristics of L. monocytogenes, such as the presence of incomplete β-hemolysis, positive CAMP reaction with S. aureus and negative CAMP reaction with R. equi, and the use of carbohydrates as D-glucose and L-rhamnose but not from D-xylose or D-mannitol. The strains of L. monocytogenes were confirmed by polymerase chain reaction and typed by random amplified polymorphic DNA (RAPD) technique. With the primers OMP-01 and PJ108 were obtained six RAPD types, distributed as follows: eight strains of type AI, three of each type A-II, A-III and B-II, two type B-I and one strain of type A-IV. We conclude that, in 18 cases of listeriosis were obtained 20 strains of L. monocytogenes with six different genotypes, RAPD type A-I being the most frequent (8/20, 40%) among the studied strains.

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains vii, 44 p. : ill. Includes abstract. Includes bibliographical references.

Thèse (M.Sc.) -- Université Laval, 1998. / Bibliogr.: f. [119]-173. Publié aussi en version électronique.

No description available.

Eight foodborne pathogenic and spoilage Gram-positive bacteria were evaluated for their spontaneous resistance frequencies to the peptide antimicrobial nisin. In brain heart infusion (BHI) medium, nisin resistance frequencies were in the range of l06 to l08 when exposed to nisin at concentrations 2 to 4 times the minimal inhibitory concentrations. A stable nisin resistant mutant of Listeria monocytogenes Scott A was obtained by increasing stepwise exposure to nisin and subsequently characterized. Phospholipid content, fatty acid composition, phase transition temperature (Tc), and specific growth rates of the resistant mutant and parent were determined. The Tc of the resistant mutant (44.4°C) in comparison of the parent (37.4°C) indicated that significant changes occurred in the lipid composition of the mutant. Gas chromatographic analysis of fatty acids of mutant and parent revealed significant differences (P<0.05) in the proportional ratios of fatty acids; 14:0, 15:0 iso, 15:0 anteiso and 17:0 iso. cells and the concentration of nisin required for reaching a 50% maximum killing rate was five times that of sensitive cells. The bactericidal activity of nisin was more effective at 37°C than 4°C for both resistant and sensitive cells, but there was always higher survival of resistant cell than sensitive cells for both temperatures. Nisin degradation and plasmid involvement were demonstrated to not be the responsible resistance mechanism to nisin in L. monocytogenes. No cross-resistance was observed to therapeutically important antibiotics (rifampicin, chloramphenicol, vancomycin, erythromycin) and to metabolic inhibitors (CCCp, DCCD) by the nisin-resistant mutant. / Graduation date: 1993

Listeria monocytogens can be found widely in nature. It can grow at refrigeration temperature, low pH, and high salt. The disease that it caused a fatality rate of 20% or higher makes L. monocytogens to be a famous foodborn pathogen. After a number of recent foodborn outbreaks, it has been demonstrated that this bacterium poses a significant health risk and has attracted the attention of the food safety professionals and public health officers. This thesis introduces the general characteristics of this bacterium, including its physiological and biochemical traits, virulent factors, infection routes, symptoms, therapy, and epidemiology. This thesis is also especially emphasized on the introduction and comparison of the differences, the advantages, as well as the disadvantages between the traditional and rapid diagnosis methods. According to the US FDA Bacterial Analytical Manual, the rapid tests had been classified into three classes: miniaturized biochemical kits, immunochemical kits, and genetic kits. The principles, formats, techniques, commercial products and its production companies of each diagnosis methods are also incorporated in this thesis. The advantages and disadvantages of these methods and their applications have been assessed. Finally, we also evaluated the market of the traditional methods being used and the rapid tests in the world, including the US, and European Union. In conclusion, the diagnosis of this important bacterium both by rapid methods or newly developed biochip and sensor will continue to grow in the future.

Thèse de doctorat : Procédés biotechnologiques et alimentaires : INPL : 2008. / Titre provenant de l'écran-titre.