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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

Study of the molecular response of uropathogenic E. coli to ciprofloxacin in human bloodstream infection models to enhance the understanding of antibiotic therapy in urosepsis

Gandi, Senthil Kumar January 2014 (has links)
Urinary tract infection (UTI) is a major burden for healthcare due to high prevalence and increasing multi-drug resistance, and advance to urosepsis which accounts up to 20-30% of sepsis cases. Therapy failures due to inappropriate antibiotic treatment are a serious issue. We are studying the transcriptomic response of the uropathogenic strain E. coli CFT073 to antibiotic treatment during bloodstream infection (BSI) models in order to understand and avoid antibiotic therapy failures in bloodstream infection/urosepsis treatments which are caused by in vivo and in vitro differences of bacterial response to antibiotic challenge which cannot be explained by antibiotic resistance mechanisms. Bloodstream infection models and controls were established by growing E. coli CFT073 in Iso-Sensitest medium, pooled human serum, and pooled human whole blood with and without ciprofloxacin. The minimum inhibitory concentration (MIC) values for E. coli CFT073 in these models were identified and used to set the antibiotic challenge in the serum/blood cultures. The antibiotic challenge was introduced at mid logarithmic phase of growth of the organism to depict a clinical scenario. Global gene expression profiling of these conditions was examined using E. coli Genechip 2.0 from Affymetrix. Data analysis was performed using the Partek Genomics Suite. The difference in the growth medium was well reflected in the growth pattern. In contrast to the growth in IST, the growth in whole blood was double the duration and growth in human serum was 6 fold longer. This difference was also reflected in the transcriptomic study where metabolic genes were regulated differently in each medium as expected. When comparing the responses to antibiotic challenge, bacteria grown in the respective medium displayed specific responses to the antibiotic challenge which were not seen in the other media. The common functions of genes that responded to the ciprofloxacin challenge were SOS response, DNA repair, DNA replication, fimbrial genes and bacteriophage initiation. A subset of the bacteriophage genes showed similar responses between the three models. From genes that were differentially regulated, responses observed in the serum model appeared to have the highest fold changes; this could be an inverse proportion to the nutrient availability in the medium. In this study we have established new models to investigate bloodstream infections based on human serum and whole blood. They have been used to identify previously unknown differences in the molecular response to antibiotic treatment by the uropathogenic E. coli CFT073 depending on the media. In ongoing and future studies we will exploit these differences in gene expression as biomarkers of bacterial response to antibiotics for the development of diagnostic tools for antibiotic therapy monitoring and as well as tools for diagnostics and stratification in drug development.
2

Nutroterapia parenteral, crescimento de biofilmes e fatores associados à infecção do cateter venoso central / Parenteral Nutrition, Biofilms and bloodstream infection associated to central venous catheter

Machado, Juliana de Carvalho 24 May 2010 (has links)
A introdução da nutroterapia parenteral (NTP) contribuiu para redução da morbimortalidade de pacientes com contraindicação de uso do trato gastrointestinal. Porém, está relacionada a complicações clínicas, destacando-se a infecção associada ao uso de cateteres venosos centrais (CVCs) e a formação de biofilmes, que podem contribuir para piora clínica daqueles que necessita da NTP. O objetivo deste estudo foi avaliar a presença de biofilmes, a infecção sanguínea secundária ao uso de CVC utilizados em nutroterapia e os fatores de riscos associados ao processo infeccioso. Por meio de estudo clínico prospectivo, durante janeiro a junho de 2008, avaliou-se clinicamente por meio de registros médicos e de enfermagem todos pacientes em uso de parenteral internados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, assim como os cateteres utilizados pelos mesmos, por meio de técnicas de cultura semiquantitativas e de hemoculturas. Aleatoriamente, algumas amostras dos CVCs utilizados foram enviadas para microscopia eletrônica de varredura e de alguns pacientes e de alguns profissionais da saúde foram coletados amostras se swab de pele. Foram avaliados 145 pacientes com idade média de 53±16 anos, destes 46% cursaram com infecção associada ao uso de CVC, ocorrendo óbito em 43% dos casos. A mortalidade foi associada ao maior risco de infecção (0.007),a complicações metabólicas como hiperglicemia (p <0.001) e distúrbio hidroeletrolítico (p=0.036) e à desnutrição (p=0.03). Com relação ao CVC, foram analisados um total de 179 CVCs, desses 49% estavam colonizados por micro-organismos e 34% foram relacionados à infecção sanguínea, não foram observadas diferenças clínicas quanto ao risco de colonização ou infecção sistêmica relacionada aos CVCs. Observou-se o risco de infecção cruzada em 21% do swabs auriculares coletados da equipe de saúde que assitia ao paciente. O risco da migração de micro-organismo da própria pele do paciente foi observado em 45% dos swabs coletados da mão e da região auricular do paciente. Quanto ao biofilme, foi observado a formação em 62% das amostras analisadas, sendo cocos mais comuns e Staphylococcus spp (39%) e Candida spp (19%) os micro-organismos mais frequentes. Conclui-se que a presença de biofilmes e infecção associada ao CVC utilizado para NTP é frequente e está relacionada ao aumento da mortalidade dos pacientes que necessitam desta nutroterapia / The introduction of parenteral nutrition therapy (PNT) has helped to reduce morbidity and mortality of patients with contraindications for use of the gastrointestinal tract. However, is related to clinical complications, especially infection associated with the use of central venous catheters (CVCs) and the formation of biofilms, which may contribute to clinical worsening of those who need the PNT. The aim of this study was to evaluate the presence of biofilms, the risk of infection related to the use of CVC used in parenteral nutrition, as well as risk factors associated with infection. Through a prospective study during January to June 2008 were evaluated clinically by means of medical records and nursing all patients who needed parenteral nutrition support at Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto, as well as catheters used by them, by means of semiquantitative culture techniques and blood cultures. Randomly, some samples of CVCs used were sent for scanning electron microscopy. Also, some samples of skin´s swabs were collected from, some patients and some health professionals. We evaluated 145 patients with mean age 53 ± 16 years, 46% of those presenting with infection associated with the use of CVC, death occurring in 43% of cases. Mortality was associated with increased risk of infection (0.007), hyperglycemia (p <0.001), electrolyte disturbance (p = 0.036) and malnutrition (p = 0.03). Regarding the CVC were analyzed a total of 179 CVCs, 49% of these were colonized by micro-organisms and 34% were related to bloodstream infection, there were no clinical differences between the risk of colonization or bloodstream infection related to CVCs. It was noted the risk of cross infection in 21% of ear swabs collected from the health team whom attended to the patient. The risk of migration of micro-organism of the patient\'s own skin was observed in 45% of the swabs collected from the hand and around patient´s ear. Biofilm formation was observed in 62% of samples, being more common cocci. Staphylococcus spp (39%) and Candida spp (19%) were the most frequent micro-organisms. The presence of biofilms and infection related to CVC used for NTP is frequent and is associated with increased mortality of patients who need this nutritional support.
3

Nutroterapia parenteral, crescimento de biofilmes e fatores associados à infecção do cateter venoso central / Parenteral Nutrition, Biofilms and bloodstream infection associated to central venous catheter

Juliana de Carvalho Machado 24 May 2010 (has links)
A introdução da nutroterapia parenteral (NTP) contribuiu para redução da morbimortalidade de pacientes com contraindicação de uso do trato gastrointestinal. Porém, está relacionada a complicações clínicas, destacando-se a infecção associada ao uso de cateteres venosos centrais (CVCs) e a formação de biofilmes, que podem contribuir para piora clínica daqueles que necessita da NTP. O objetivo deste estudo foi avaliar a presença de biofilmes, a infecção sanguínea secundária ao uso de CVC utilizados em nutroterapia e os fatores de riscos associados ao processo infeccioso. Por meio de estudo clínico prospectivo, durante janeiro a junho de 2008, avaliou-se clinicamente por meio de registros médicos e de enfermagem todos pacientes em uso de parenteral internados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, assim como os cateteres utilizados pelos mesmos, por meio de técnicas de cultura semiquantitativas e de hemoculturas. Aleatoriamente, algumas amostras dos CVCs utilizados foram enviadas para microscopia eletrônica de varredura e de alguns pacientes e de alguns profissionais da saúde foram coletados amostras se swab de pele. Foram avaliados 145 pacientes com idade média de 53±16 anos, destes 46% cursaram com infecção associada ao uso de CVC, ocorrendo óbito em 43% dos casos. A mortalidade foi associada ao maior risco de infecção (0.007),a complicações metabólicas como hiperglicemia (p <0.001) e distúrbio hidroeletrolítico (p=0.036) e à desnutrição (p=0.03). Com relação ao CVC, foram analisados um total de 179 CVCs, desses 49% estavam colonizados por micro-organismos e 34% foram relacionados à infecção sanguínea, não foram observadas diferenças clínicas quanto ao risco de colonização ou infecção sistêmica relacionada aos CVCs. Observou-se o risco de infecção cruzada em 21% do swabs auriculares coletados da equipe de saúde que assitia ao paciente. O risco da migração de micro-organismo da própria pele do paciente foi observado em 45% dos swabs coletados da mão e da região auricular do paciente. Quanto ao biofilme, foi observado a formação em 62% das amostras analisadas, sendo cocos mais comuns e Staphylococcus spp (39%) e Candida spp (19%) os micro-organismos mais frequentes. Conclui-se que a presença de biofilmes e infecção associada ao CVC utilizado para NTP é frequente e está relacionada ao aumento da mortalidade dos pacientes que necessitam desta nutroterapia / The introduction of parenteral nutrition therapy (PNT) has helped to reduce morbidity and mortality of patients with contraindications for use of the gastrointestinal tract. However, is related to clinical complications, especially infection associated with the use of central venous catheters (CVCs) and the formation of biofilms, which may contribute to clinical worsening of those who need the PNT. The aim of this study was to evaluate the presence of biofilms, the risk of infection related to the use of CVC used in parenteral nutrition, as well as risk factors associated with infection. Through a prospective study during January to June 2008 were evaluated clinically by means of medical records and nursing all patients who needed parenteral nutrition support at Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto, as well as catheters used by them, by means of semiquantitative culture techniques and blood cultures. Randomly, some samples of CVCs used were sent for scanning electron microscopy. Also, some samples of skin´s swabs were collected from, some patients and some health professionals. We evaluated 145 patients with mean age 53 ± 16 years, 46% of those presenting with infection associated with the use of CVC, death occurring in 43% of cases. Mortality was associated with increased risk of infection (0.007), hyperglycemia (p <0.001), electrolyte disturbance (p = 0.036) and malnutrition (p = 0.03). Regarding the CVC were analyzed a total of 179 CVCs, 49% of these were colonized by micro-organisms and 34% were related to bloodstream infection, there were no clinical differences between the risk of colonization or bloodstream infection related to CVCs. It was noted the risk of cross infection in 21% of ear swabs collected from the health team whom attended to the patient. The risk of migration of micro-organism of the patient\'s own skin was observed in 45% of the swabs collected from the hand and around patient´s ear. Biofilm formation was observed in 62% of samples, being more common cocci. Staphylococcus spp (39%) and Candida spp (19%) were the most frequent micro-organisms. The presence of biofilms and infection related to CVC used for NTP is frequent and is associated with increased mortality of patients who need this nutritional support.
4

Incidence of Vancomycin-Resistant Enterococci (vre) Infection in High-Risk Febrile Neutropenic Patients Colonized with Vre

Bossaer, John B., Hall, Philip D., Garrett-Mayer, Eliabeth 01 February 2011 (has links)
Purpose: This study seeks to determine the incidence of vancomycin-resistant enterococci (VRE) infection in high-risk neutropenic fever patients colonized with VRE and to determine patient characteristics associated with VRE infection. Methods: We conducted a retrospective, single-center, unmatched case-control study. Fifty-three VRE-colonized, high-risk patients with neutropenic fever were identified between January 2006 and February 2009. The two most common diagnoses/conditions included acute myeloid leukemia and hematopoietic stem cell transplantation. Data collected included days of neutropenia, days of fever, demographic data, culture results, and antimicrobial therapy. Results: Twenty of the 53 patients (38%) with VRE colonization developed a VRE infection. The most common VRE infections were bacteremias (26%). The presence of neutropenia lasting longer than 7 days was associated with the development of VRE infection in this high-risk population colonized with VRE. The timeframe to develop VRE infection varied from 1 day to 2 weeks. Conclusion: For patients colonized with VRE, approximately 38% of high-risk neutropenic patients developed a VRE infection. This is the first study to specifically evaluate the incidence of VRE infections in febrile neutropenic patients colonized with VRE. Future research into the use and efficacy of empiric VRE coverage is needed.

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