Made available in DSpace on 2018-08-23T21:50:43Z (GMT). No. of bitstreams: 1 tese_12423_Dissertação Ingrid VERSÃO FINAL.pdf: 2910032 bytes, checksum: f74a79e0492f8dbd74374a927a556dd4 (MD5) Previous issue date: 2018-05-24 / Infecções causadas por Klebsiella pneumoniae produtora de carbapenemase KPC (Kp-KPC) constituem uma grande ameaça para a prática clínica, visto que são associadas a elevadas taxas de mortalidade e possuem escassas opções terapêuticas disponíveis. Atualmente estão sendo detectadas cepas dessa bactéria com resistência a todos os agentes antimicrobianos conhecidos, corroborando a urgente necessidade por novos tratamentos eficazes. O presente estudo teve como objetivo avaliar os efeitos de fendiona e seus derivados, Cu-fendiona e Ag-fendiona, sozinhos e combinados aos carbapenêmicos meropenem (MPM) e imipenem (IMP) em diferentes amostras de Kp-KPC, in vitro e em modelo de Galleria mellonella. Para tal foram investigados: (i) os valores de concentração inibitória mínima (CIM) e de concentração bactericida mínima (CBM) dos compostos; (ii) o efeito da combinação dos compostos com MPM e IMP por meio de checkerboard e curva tempo-morte; e (iii) o efeito de combinações sinérgicas em modelo in vivo de G. mellonella. Os resultados obtidos pela determinação da CIM e da CBM demonstraram boa atividade antimicrobiana pelos três compostos contra todas as 46 amostras. Os valores médios da CIM de fendiona, Cu-fendiona e Ag-fendiona foram 42,06, 9,88, e 10,10 μg/ml, respectivamente. Por meio do checkerboard foram testadas combinações dos compostos com MPM e IMP sobre 9 amostras clonalmente não-relacionadas, e não foi observada a presença de efeitos indiferentes ou antagônicos em qualquer uma das seis combinações testadas. Maiores taxas de sinergismo foram observadas nas três combinações contendo MPM, sendo esse efeito detectado em 66,67%, 77,78%, e 33,33% das amostras quando em associação a fendiona, Cu-fendiona e Ag-fendiona, respectivamente. Pelo método de curva tempo-morte foram testadas as combinações de MPM com Cu-fendiona e Ag-fendiona sobre duas amostras clonalmente não-relacionadas. Foi demonstrado que as combinações contendo concentrações de ½ xCIM de cada agente produziram efeito sinérgico, sendo verificado entre nove e 12 horas de teste. Observou-se que a combinação de MPM com o composto Ag-fendiona foi capaz de erradicar o inóculo (106 UFC/mL) aplicado no teste. Os níveis de toxicidade aguda de fendiona e seus derivados foram avaliados em modelo de G. mellonella, sendo os resultados considerados satisfatórios no que se refere à utilização desses compostos sozinhos ou combinados. A eficácia das combinações foi também avaliada in vivo em modelo de infecção de G. mellonella sobre as mesmas duas amostras empregadas na curva tempo-morte. Foi verificada uma superioridade estaticamente significativa do tratamento com as combinações em relação à administração dos agentes sozinhos. Assim, os resultados obtidos no nosso estudo demonstram o potencial de fendiona, Cu-fendiona e Ag-fendiona como candidatos a fármacos sozinhos ou combinados a antimicrobianos carbapenêmicos.

Streptococcus pneumoniae is a bacterium responsible for a spectrum of diseases including lobar pneumonia, meningitis, otitis media, and sinusitis. Invasive pneumococcal disease is responsible for significant morbidity and mortality across the world. Concerted efforts led to the development of two vaccinations, Pneumova × 23 and Prevnar 13, for the prevention of pneumococcal disease. The Advisory Committee on Immunization Practices of the US Centers for Disease Control and Prevention provides vaccination schedules for predisposed adults, but the proposed schedules remain a challenge to health-care providers. We performed a systematic review in PubMed and these specialty group websites to present the pathophysiology of pneumococcal disease, outline different pneumococcal vaccinations, and condense recommendations for vaccination administration.

No description available.

Streptococcus pneumoniae is an asymptomatic colonizer of the upper respiratory tract as well as an opportunistic pathogen. Colonization is prerequisite to causing disease in a host, and it often involves formation of biofilms. There are currently two vaccines available against pneumococcus, both of which focus on preventing invasive disease by targeting the polysaccharide capsule of the most invasive serotypes. We hypothesized that by using membrane proteins expressed during the biofilm state, we can formulate an effective vaccine against colonization which would lead to an overall decrease in disease incidence. To do this, we selected protein candidates expressed during biofilm growth based on their ability to elicit an IgA response in human serum. Selected proteins (SP_0459, SP_1114, and SP_1702) were identified and used for further experiments. The proteins identified in this study will be paired with other immunogenic proteins to determine a successful vaccine formulation targeting colonization of Streptococcus pneumoniae.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed June 5, 2008). Includes bibliographical references.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 5 uppsatser.

Made available in DSpace on 2015-11-11T12:04:10Z (GMT). No. of bitstreams: 2 22.pdf: 3102930 bytes, checksum: 2f67ffbd3b5474aacabccf998ea6f22e (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2014 / Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães. Recife, PE, Brasil / Este estudo visou a caracterização molecular de mecanismos de virulência e resistência aos antimicrobianos em isolados de K. pneumoniae MDR provenientes de um hospital universitário em Recife-PE. Seis isolados de K. pneumoniae produtores de carbapenemase foram obtidos de pacientes hospitalizados na UTI de um hospital universitário do Recife. Os isolados apresentaram resistência a todos os antimicrobianos beta-lactâmicos e quinolonas testados, mas sensibilidade a amicacina, polimixina B e tigeciclina, por meio de microdiluição em caldo. A tipagem molecular por PFGE revelou que os isolados são intimamente relacionados, apresentando três subclones distintos. Dois STs foram detectados, o ST340 e o ST11, ambos pertencentes ao CC258. Os genes blaKPC-2 e blaSHV-11 foram detectados em todos os isolados, seguido do gene blaCTX-M-15 em quatro dos seis isolados e por fim os genes blaCTX-M-2, qnrB19, aac(6')-31 em dois dos seis isolados. Os genes blaKPC-2 e blaCTX-M-15 estavam presentes em um mesmo plasmídeo de aproximadamente 133 Kb pertencente ao IncI-gama em quatro isolados. Nos demais isolados os genes blaKPC-2 e blaCTX-M-2 eram carreados também por um plasmídeo de, aproximadamente, 133 Kb, entretanto, não foi possível tipar o mesmo com as metodologia utilizada. O gene qnrB19 foi detectado sendo carreado por um plasmídeo de 15 Kb pertencente ao IncY. Todos os isolados apresentaram integron de classe 1, associado com a resistência aos aminoglicosídeos / Mutações na região QRDR de GyrA (Ser83Ile) e ParC (Ser80Ile) foram detectadas em todos os isolados analisados, sendo esse o principal mecanismo de resistência as quinolonas detectadas ao longo do estudo. Adicionalmente, a permeabilidade de membrana externa foi analisada, verificando-se a ausência da Ompk35 em todos os isolados e da OmpK36 em uma das amostras analisadas. A investigação dos genes de virulência revelou a presença de antígenos capsulares do tipo K2 entre os isolados. Genes codificadores das fímbrias do tipo I e III foram detectados, assim como genes envolvidos na síntese de LPS e operon da urease. A presenca de micro-organismos multirresistentes e virulentos em unidades hospitalares reforça a necessidade de medidas para a rápida contenção de possíveis infecções hospitalares causadas por esses patógenos

Klebsiella pneumoniae is one of the top eight pathogens in hospitals, causing around 10% of hospital-acquired infections (nosocomial infections). It often produces extended-spectrum β-lactamase enzymes (ESBLs). This has led to numerous outbreaks, especially in intensive care, neonatal and surgical wards, associated with increases in morbidity and mortality. In order to reduce the number of infections caused by multi-resistant K. pneumoniae and improve standards of infection control within hospitals, there is extensive use of biocides as disinfectants and antiseptics. However this raises concerns that intensive exposure of hospital pathogens to biocides may result in the emergence of resistance not just to themselves but also to antibiotics. The reduced susceptibility to biocides and their relationship with resistance to antibiotics was assessed in this thesis. The susceptibility of 64 isolates of K. pneumoniae to five biocides preparations, Chlorhexidine (CHX), Benzalkonium chloride (BZK), Trigene, MediHex-4 (MH-4), Mediscrub (MS) and 17 antibiotics, were tested. The isolates of K. pneumoniae were collected from Royal Infirmary Hospital in Edinburgh (RIE) between 2006 and 2008 from different sites of infection. Antimicrobial susceptibility was tested by the agar double dilution method (DDM) and disc diffusion methods following the British Society for Antimicrobial Chemotherapy (BSAC) guidelines. A few isolates of K. pneumoniae showed insusceptibility to cephalosporins, colistin, rifampicin, trimethoprim and penicillin but not to carbapenems. Biocide susceptibility testing showed that 57, 55 and 61 strains had reduced susceptibility to Chlorhexidine, Trigene and Benzalkonium chloride, respectively, but not to MediHex-4 and Mediscrub. The effect of efflux pumps were determined by carbonyl cyanide m-chlorophenylhydrazone (CCCP) (10mg/L), which decreased the MICs of Chlorhexidine and Medihex-4 by 2 – 128 fold but had no impact on the MICs of Benzalkonium chloride, Trigene and Mediscrub. Six isolates of K. pneumoniae were chosen for their varying sensitivity to Chlorhexidine (CHX), and were tested for their minimum bactericidal concentration (MBC) to biocides. The high MBCs of Mediscrub and Trigene, over 500-fold greater than the minimum inhibitory concentration (MICs), indicates that these compounds are mainly bacteriostatic. Conversely, the MBCs of Chlorhexidine and MediHex-4, which contains chlorhexidine, were less than 10-times the MIC value indicating they are effective in killing the organism. However, this thesis showed how the killing capability of Chlorhexidine was hindered by the presence of organic matter, which compromised its effect. The relationship between reduced susceptibility to biocides and the carriage of antiseptic resistance genes, cepA, qacΔE1 and qacE was determined by polymerase chain reaction. The antiseptic resistance genes cepA, qacΔE1 and qacE were found in 56, 34 and 1 isolates respectively, and the levels of gene expression were detected by the reverse transcription polymerase chain reaction (RT-PCR). These results have shown that there was a close link between carriage of efflux pump genes, cepA, qacΔE1 and qacE genes and reduced susceptibility to biocides. Most strains showed decreased susceptibility to Chlorhexidine, Trigene and Benzalkonium chloride and this correlated with the carriage of the cepA, qacΔE1 and qacE genes encoding efflux. There was no correlation between the reduced susceptibility to biocides and antibiotic resistance in clinical isolates of K. pneumoniae.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Arginine uptake and degradation systems are common throughout bacteria and archaea. The genome of human pathogen Chlamydia pneumoniae encodes three proteins now called AaxA, AaxB, and AaxC which function together to take up arginine, decarboxylate it, and expel the decarboxylation product, agmatine. AaxB is the previously characterized pyruvoyl-dependent arginine decarboxylase, AaxC is an inner membrane amino acid transport protein that functions as an arginine-agmatine antiporter, and AaxA is an outer membrane porin, which facilitates the uptake of arginine and also functions as a general porin with broad specificity. C. pneumoniae is a non-typical Gram negative bacteria and an obligate intracellular parasite with a unique 2-phase life cycle. The role of this system for arginine-agmatine exchange has yet to be determined but it may function to deplete host cell arginine as a means of inactivating host inducible nitric oxide synthase (iNOS), a molecule used in the innate immune response that has been shown to have an inhibitory affect on the growth of C. pneumoniae in cell culture. AaxB and AaxC are able to complement the loss of extreme acid-resistance in E. coli mutants that lack their own system for arginine-agmatine exchange, making pH homeostasis another possible role for this system. The porin AaxA is able to enhance arginine-agmatine exchange by AaxB and AaxC in E. coli mutants as well as by the native arginine decarboxylase AdiA and the native arginine-agmatine antiporter AdiC in wild type E. coli. AaxA is not an arginine-specific porin and instead acts as a general porin with a broad specificity. AaxA discriminates only against large and negatively charged solute molecules, and therefore it may have a broad role in the uptake of various biomolecules essential for chlamydial growth in addition to its role as part of a system for arginine-agmatine exchange. / text