Navegando por Palavras-chave "Polymyxin B"
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- ItemSomente MetadadadosAntimicrobial resistance in Enterobacteriaceae in Brazil: focus on beta-lactams and polymyxins(Soc Brasileira Microbiologia, 2016) Mello Sampaio, Jorge Luiz; Gales, Ana Cristina [UNIFESP]uring the last 30 years there has been a dissemination of plasmid-mediated beta-lactamases in Enterobacteriaceae in Brazil. Extended spectrum beta-lactamases (ESBL) are widely disseminated in the hospital setting and are detected in a lower frequency in the community setting. Cefotaximases are the most frequently detected ESBL type and Klebsiella pneumoniae is the predominant species among ESBL producers. Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae became widely disseminated in Brazil during the last decade and KPC production is currently the most frequent resistance mechanism (96.2%) in carbapenem resistant K. pneumoniae. To date KPC-2 is the only variant reported in Brazil. Polymyxin B resistance in KPC-2-producing K. pneumoniae has come to an alarming rate of 27.1% in 2015 in Sao Paulo, the largest city in Brazil. New Delhi metallo-beta-lactamase was detected in Brazil in 2013, has been reported in different Brazilian states but are not widely disseminated. Antimicrobial resistance in Enterobacteriaceae in Brazil is a very serious problem that needs urgent actions which includes both more strict adherence to infection control measures and more judicious use of antimicrobials.(C) 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda.
- ItemAcesso aberto (Open Access)Heterorresistência à colistina e polimixina b em Klebsiella pneumoniae: prevalência, métodos de detecção e perspectiva terapêutica.(Universidade Federal de São Paulo, 2023-06-26) Augusto, Mariana de Freitas [UNIFESP]; Minarini, Luciene Andrade da Rocha [UNIFESP]; http://lattes.cnpq.br/5226657617185982Heterorresistência à colistina e polimixina B em Klebsiella pneumoniae refere-se a um fenômeno em que subpopulações aparentemente isogênicas se destacam em uma população bacteriana sensível, exibindo diferentes níveis de sensibilidade a esses antibióticos. Embora pouco se conheça sobre o significado clínico da heterorresistência a antibióticos, foram relatados, em literatura, casos de falha do tratamento antimicrobiano associados com heterorresistência à colistina em K. pneumoniae. Com base no exposto, o objetivo principal do estudo foi investigar a prevalência de heteroresistência à `colistina e/ou polimixina B em K. pneumoniae a partir da análise de literatura científica, verificar os métodos de detecção de heterorresistência disponíveis e explorar as perspectivas terapêuticas para enfrentar essa ameaça emergente. Para esta revisão da literatura, foram realizadas buscas na plataforma PubMed, no período de 10 a 12 de abril de 2023, na qual foram selecionados artigos publicados no período de janeiro de 2019 à abril de 2023. Foi utilizado como critério de inclusão o idioma, sendo incluídos somente artigos na língua inglesa e na língua portuguesa. Em seguida, foram excluídos os artigos em duplicidade, artigos de revisão e artigos não disponíveis na íntegra. Por fim, foram excluídos artigos que não se encaixavam na proposta trazida para este trabalho. Baseado nisso, foram incluídos 13 estudos relacionados à temática da revisão. Foi possível observar neste estudo que a prevalência da heterorresistência à colistina e/ou polimixina B variou entre 1,3% e 100% nos artigos analisados. Quanto aos métodos de detecção, observou-se que os métodos convencionais de teste de sensibilidade podem falhar na detecção da heterorresistência, sendo a análise do perfil populacional (PAP) um método mais confiável, embora trabalhoso. Por fim, este estudo mostrou que a terapia combinada é a recomendada para tratar infecções causadas por cepas de K. pneumoniae heterorresistentes.
- ItemAcesso aberto (Open Access)Infecção da corrente sanguínea causada por Pseudomonas aeruginosa resistente aos carbapenêmicos: fatores associados a mortalidade e influência da terapia combinada com polimixina B e imipenem(Universidade Federal de São Paulo (UNIFESP), 2011-07-27) Teixeira, Jane de Oliveira Gonzaga [UNIFESP]; Medeiros, Eduardo Alexandrino Servolo de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Pseudomonas aeruginosa is an important pathogen causing nosocomial bloodstream infections. The treatment of carbapenem-resistant P. aeruginosa is a challenge as the drugs used for this purpose, the polymyxins, have lower activity compared with carbapenems. However, it has been suggested that polymyxins have the ability to make gram-negative bacteria more susceptible to other antibiotics. As carbapenems are considered the main drugs against P. aeruginosa, it would be interesting to demonstrate the efficacy of this combination in vivo, targeting a more effective therapy. Objectives: To evaluate the response of the treatment with polymyxin B versus polymyxin B and carbapenem in patients with nosocomial bloodstream infection caused by carbapenenresistant Pseudomonas aeruginosa and identify factors associated with mortality among those patients Methods: A retrospective cohort study was performed at Hospital São Paulo - UNIFESP, from January 1st, 2000 to December 31, 2009. The identification of patients was done through data collection from the blood cultures report. Patients were initially divided into deaths and survivors, and assessed for exposure to various factors potentially associated with in-hospital mortality and infection-related mortality. Presence of metalobetalactamase was tested trough PCR technique. Results: We studied 69 bloodstream infections caused by carbapenems-resistant P. aeruginosa. Thirthy-five were treated with polymyxin B monotherapy and 34 with combined therapy. In- hospital mortality was 77.1% and 79.4% in the monotherapy group and combined therapy group, respectively (p = 0.819). The infection-related mortality was 42.8% among patients who received monotherapy, and 44.1% in those receiving combined therapy (p = 0.917). Factors associated with mortality were previous use of glycopeptides (OR 10.71, CI95% 1.20 to 95.34, p = 0.033) and Charlson score (OR 1.9, CI95% 1, 22 to 2.94, p = 0.004). Infection-related mortality was associated with the presence of septic shock (OR 9.99, CI95% 1.81 to 55.22, p = 0.006) and parenteral nutrition (OR 7.45, CI95% 1.23 - 45.24, p = 0.029). No statistically significant difference was found between patients with MBLharboring and non-MBL-harboring strains treated with combined therapy. Conclusions: No difference was found between the monotherapy and combined therapy group regarding mortality. Independent factors related to in- hospital mortality were prior use of glycopeptides and the Charlson score. Presence of septic shock and use of parenteral nutrition were independently associated with infection-related mortality.
- ItemAcesso aberto (Open Access)Influência dos Métodos de Sensibilidade aos Antimicrobianos no Uso Clínico das Polimixinas(Universidade Federal de São Paulo (UNIFESP), 2010-05-04) Silva, Itacy Gonçalves de Siqueira e [UNIFESP]; Gales, Ana Cristina [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Introduction: Acinetobacter spp. e Pseudomonas aeruginosa are important pathogens that cause infections in Brazilian hospitals and have become resistant to almost every available antimicrobial. Thereby, the clinical indication of parenteral use of polymyxin has been reestablished in recent years. Therefore, the clinical laboratory of microbiology need be able to perform reliable susceptibility antimicrobial tests. Objective: Analyze the influence of susceptibility antimicrobial tests in the clinical use of polymyxins. Material and Methods: Nine P. aeruginosa and 10 Acinetobacter spp. strains were tested to polymyxin susceptibility. The results of agar dilution, broth microdilution and Etest were compared, according CSLI. The influence of culture medium, calcium concentration, inoculum concentration and incubation time in the susceptibility antimicrobial test was evaluated. Results: There was good agreement between different polymyxin antimicrobial susceptibility methods for Acinetobacter spp isolates, but not for P. aeruginosa. It was observed 100% of agreement between Iso-sensitest and Müeller-Hinton medium through agar dilution and Etest for Acinetobacter spp. isolates. Through broth microdilution occurred 90% of agreement for polymyxin B and 60% for colistin. Between P. aeruginosa isolates, Etest had greater MIC variation when using different culture mediuns. In general, BHI medium had low MICs comparing with Müller- Hinton. The calcium concentration increase in the culture medium promoted MICs elevation in ±1Log2 of dilution, for both microrganisms. Etest had 55,6% (polymyxin B) and 88,9% (colistin) of minor error, and 11,1% of major error in polymyxin B. Inoculum size had greater influence in agar dilution, with minor error rates of 10% (polymyxin B) and 30% (colistin) for Acinetobacter spp. isolates, and 33,3% (polymyxin B) and 66,6% (colistin) for P. aeruginosa isolates. Different time incubations caused MICs variation only between P. aeruginosa isolates. Etest method had 33,3% (polymyxin B) and 44,4%(colistin) of minor error. Through agar dilution, the minor error rate was 11,1% with incubation time variation.
- ItemSomente MetadadadosMicrobiological and epidemiological characterization of imipenem-resistant Pseudomonas aeruginosa strains from a Brazilian tertiary hospital: Report from the SENTRY Antimicrobial Surveillance Program(Esift Srl, 2006-10-01) Ribeiro, Julival; Mendes, Rodrigo Elisandro [UNIFESP]; Domingos, R.; Franca, E.; Silbert, Suzane [UNIFESP]; Jones, Ronald N.; Sader, Helio Silva [UNIFESP]; Hosp Base Distrito Fed; Universidade Federal de São Paulo (UNIFESP); JMI LabsOBJECTIVES: To evaluate the antimicrobial susceptibility profile, the genetic similarity, and the mechanisms of carbapenem resistance among imipenem-resistant Pseudomonas aeruginosa isolates collected from a Brazilian tertiary teaching hospital.METHODS: Seventy-eight consecutive samples of P. aeruginosa were evaluated during 2000 and 2001. The antimicrobial susceptibility was evaluated by reference broth microdilution methods and the imipenem-resistant isolates were screened for metallo-p-lactamase (MPL) production throughout disc approximation test and MOL Etest (R) strips and isolates with positive screen test result were submitted to PCR assays using primers bla(IMP-1), bla(VIM-1), bla(VIM-2) e bla(SPM-1). The genetic similarity of MOL-producing strains was evaluated by automated ribotyping for epidemiological typing purpose.RESULTS: Resistance rates were high to the majority of antimicrobial agents tested except polymyxin B, which inhibited all samples at the Clinical and Laboratory Standards Institute breakpoint (<= 2 mu g/ml). Twenty-nine (37.2%) isolates were resistant to imipenem and these isolates showed great genomic variability. MPL production was demonstrated in two imipenem-resistant isolates, which were detected using bla(SPM-1) and bla(IMP-2)-specific primers. Sequence analysis revealed the presence of bla(SPM-1) and a novel biamp-type gene, bla(IMP)-typeCONCLUSION: The results of this study showed high resistance rates to the majority of antimicrobial agents among P. aeruginosa samples. High imipenem resistance rates were probably due to continuous selection of resistant mutants. The production of MOL did not represent a frequent mechanism of carbapenem resistance in this medical center; but a novel MPL was identified. Continued antimicrobial surveillance and infection control measures should be emphasized to minimize the emergence and dissemination of antimicrobial resistance.
- ItemAcesso aberto (Open Access)Nephrotoxicity Of Polymyxin B: Experimental Study In Cells And Implications For Nursing Practice(Universidade de São Paulo, Escola de Enfermagem, 2014-04-01) Neiva, Luciana Barros de Moura; Borges, Fernanda Teixeira; Watanabe, Mirian; Pessoa, Edson de Andrade; Barbosa, Dulce Aparecida [UNIFESP]; Vattimo, Maria de Fatima Fernandes; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)The aim of the study was to characterize the cell damage mechanisms involved in the pathophysiology of cytotoxicity of polymyxin B in proximal tubular cells (LLC - PK1) and discuss about the nurses interventions to identify at risk patients and consider prevention or treatment of nephrotoxicity acute kidney injury. This is a quantitative experimental in vitro study, in which the cells were exposed to 375μM polymyxin B sulfate concentration. Cell viability was determined by exclusion of fluorescent dyes and morphological method with visualization of apoptotic bodies for fluorescence microscopy. Cells exposed to polymyxin B showed reduced viability, increased number of apoptotic cells and a higher concentration of the enzyme lactate dehydrogenase. The administration of polymyxin B in vitro showed the need for actions to minimize adverse effects such as nephrotoxicity.
- ItemAcesso aberto (Open Access)The polymyxin B-induced transcriptomic response of a clinical, multidrug-resistant Klebsiella pneumoniae involves multiple regulatory elements and intracellular targets(Biomed Central Ltd, 2016) Ramos, Pablo Ivan Pereira; Custodio, Marlon Gregori Flores; Quispe Saji, Guadalupe del Rosario; Cardoso, Thiago; Silva, Gisele Lucchetti da; Braun, Graziela [UNIFESP]; Martins, Willames M. B. S. [UNIFESP]; Girardello, Raquel [UNIFESP]; Vasconcelos, Ana Tereza Ribeiro de; Fernandez, Elmer; Gales, Ana Cristina [UNIFESP]; Nicolas, Marisa FabianaBackground: The emergence of multidrug-resistant Klebsiella pneumoniae is a major public health concern. Many K. pneumoniae infections can only be treated when resorting to last-line drugs such as polymyxin B (PB). However, resistance to this antibiotic is also observed, although insufficient information is described on its mode of action as well as the mechanisms used by resistant bacteria to evade its effects. We aimed to study PB resistance and the influence of abiotic stresses in a clinical K. pneumoniae strain using whole transcriptome profiling. Results: We sequenced 12 cDNA libraries of K. pneumoniae Kp13 bacteria, from two biological replicates of the original strain Kp13 (Kp13) and five derivative strains: induced high-level PB resistance in acidic pH (Kp13(pH)), magnesium deprivation (Kp13(Mg)), high concentrations of calcium (Kp13(Ca)) and iron (Kp13(Fe)), and a control condition with PB (Kp13(PolB)). Our results show the involvement of multiple regulatory loci that differentially respond to each condition as well as a shared gene expression response elicited by PB treatment, and indicate the participation of two-regulatory components such as ArcA-ArcB, which could be involved in re-routing the K. pneumoniae metabolism following PB treatment. Modules of co-expressed genes could be determined, which correlated to growth in acid stress and PB exposure. We hypothesize that polymyxin B induces metabolic shifts in K. pneumoniae that could relate to surviving against the action of this antibiotic. Conclusions: We obtained whole transcriptome data for K. pneumoniae under different environmental conditions and PB treatment. Our results supports the notion that the K. pneumoniae response to PB exposure goes beyond damaged membrane reconstruction and involves recruitment of multiple gene modules and intracellular targets.