Navegando por Palavras-chave "OXA-23"

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    Diversity of mechanisms conferring resistance to beta-lactams among OXA-23-producing Acinetobacter baumannii clones
    (Elsevier Science Inc, 2016) Cardoso, Juliana Provasi [UNIFESP]; Cayo, Rodrigo [UNIFESP]; Girardello, Raquel [UNIFESP]; Gales, Ana Cristina [UNIFESP]
    A total of 31 unrelated OXA-23-producing Acinetobacter baumannii strains isolated from 14 hospitals located in distinct Brazilian regions were evaluated in this study. These isolates were grouped into 12 different sequence types (STs), of which 7 had unique allelic sequences (ST188, ST189, ST190, ST191, ST192, ST228, and ST299). Most isolates belonged to the clonal complex CC79 followed by CC15 and CC1. Only polymyxin B and minocycline showed good activity against the OXA-23-producing A. baumannii clones. The ISAba1 upstream bla(OXA-23), bict(OXA-51)-like, or ampC was found in 100%, 54.8%, and 77.4% of the isolates, respectively. High resistance rates to ceftazidime and cefotaxime were observed among those isolates possessing ISAba1 upstream ampC, in contrast to those isolates that did not carry this configuration. Moreover, a >= 2 Log(2) decrease in the MICs of meropenem and ceftazidime was observed in the presence of phenyl-arginine-beta-naphthylamide for 80.6% and 54.8% of isolates, respectively. Overexpression of the adeB was observed in 61.3% of isolates, particularly among those isolates belonging to the ST1 (CC1). It was also verified that ompW was down -regulated in all isolates belonging to the ST15 (CC15). On the other hand, carO and omp33-36 genes were overexpressed in 48.4% and 58.1% of the isolates, respectively. In this study, we show that overexpression of AdeABC system could significantly contribute for resistance to meropenem and ceftazidime among OXA-23-producing A. baumannii clones in Brazil, demonstrating the complexity involved in the p-lactam resistance in such isolates. (C) 2016 Elsevier Inc. All rights reserved.
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    Estudo da Similaridade Genética de Amostras de Acinetobacter baumannii Produtoras de Carbapenemases do Tipo OXA Isoladas em Diversos Hospitais Brasileiros
    (Universidade Federal de São Paulo (UNIFESP), 2010-09-29) Werneck, Jessica Sanchez de Freitas [UNIFESP]; Gales, Ana Cristina [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In this dissertation we present two studies involving carbapenem-resistant Acinetobacter baumannii clinical isolates due to the production of carbapenems modifying enzymes, the OXA-type carbapenemases. The first study aimed to determine the genetic relationship of multi-drug-resistant A. baumannii producing OXA-23 that was isolated in distinct Brazilian cities. A total of 91 A. baumannii clinical isolates were recovered from 17 medical centers located at eight cities, namely São Paulo (SP), Rio de Janeiro (RJ), Belo Horizonte (MG), Porto Alegre (RS), Blumenau (SC), Curitiba (PR), São Luiz (MA) and Salvador (BA). In this collection we observed high rates of carbapenems resistance (91.2%). Also, the blaOXA- 23-like gene was present in 83.5% of isolates. The insertion sequence ISAba1 was positioned upstream the blaOXA-23 gene in all OXA-23-producing A. baumannii identified. Nine clusters were observed among OXA-23 producers. Our fidings suggest that the blaOXA-23 gene was probably chromosomally-located in all isolates studied. Three clusters (A, B and D) were found in six cities from southeast and southern reagions of Brazil. In addition, the predominant cluster (A) was clonally related to that first described in Curitiba, in2003. In contrast, a single cluster of A. baumannii producing OXA-23 was found in São Luís city. Although there were previous reports regarding the spread of OXA-23-producing A. baumannii in Brazil the following features had not yet been assessed: i) the comparative analysis of OXA-23 producers genotypes originating in distinct and distant Brazilian cities, ii) the genetic location of the blaOXA-23 gene and iii) the presence of ISAba1 upstream blaOXA-23 probably resulting in high degree of carbapenem resistance. Thus, our study demonstrates that the clonal dissemination of OXA-23- producing A. baumannii had occurred in Brazil. These findings emphasize that infection control measures are urgently needed to reduce both the spread of multidrug resistantstrains and the number of infections caused by this pathogen. The second study refers to a case report involving a hospitalized patient that presented an wound infection due to OXA-72-producing A. baumannii. The referred clinical isolate, A 30235, was resistant to most antibiotics tested and showed reduced susctptibility to ampicillin/sulbactam. Successful transformation assays using A. baumannii ATCC 19606 as the recipient strain revealed the plasmid location of the blaOXA-72 gene. This plasmid showed molecular weight of about 86 Kb. We identified for the first time in Brazil, an A. baumannii clinical isolate producing OXA-72. The presence of this resistance determinant encoded by a gene located in a mobile genetic elemet, points out to an increasing diversity of OXA-type carbapenemase in Brazil with potential spread. Appropriate control measures should be taken to prevent the spread of OXA-72 producers among Brazilian hospitals, which it we have experienced with OXA-23- producing-A. baumannii in this country.
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    Temporal evolution of carbapenem-resistant Acinetobacter baumannii in Curitiba, southern Brazil
    (Elsevier B.V., 2010-05-01) Schimith, Karina Eugenia; Luiz, Simone Oliveira; Scheffer, Mara Cristina; Gales, Ana Cristina [UNIFESP]; Paganini, Maria Cristina; Nascimento, Agnaldo Jose do; Carignano, Evelyn; Dalla Costa, Libera Maria; Universidade Federal do Paraná (UFPR); Universidade Federal de Santa Catarina (UFSC); Universidade Federal de São Paulo (UNIFESP); Univ Tuiuti Parana; Pequeno Principe Coll Pele Pequeno Res Inst FPP I
    Background: in the last few years, carbapenem-resistant Acinetobacter baumannii isolates (CR-AB) have been identified worldwide. the first description of OXA-23-producing A baumannii in Brazil was from the city of Curitiba in 2003. the aim of the present study was to evaluate the persistence and dissemination of the first OXA-23-producing A baumannii clone isolated from patients in Hospital de Clinicas, Curitiba, Brazil.Methods: An antimicrobial susceptibility profile of the isolates was determined by the standard agar dilution method. Molecular detection of beta-lactamase genes was done by polymerase chain reaction. the clonal relationship of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE). Epidemiologic and clinical features were evaluated as well.Results: Genotypic analysis of 172 CR-AB isolates by PFGE identified 3 distinct major PFGE clusters (A, B, and C, accounting for 36, 69, and 65 isolates, respectively). All isolates carried the bla(OXA-23)-like gene and were multidrug-resistant, but were susceptible to tigecycline and polymixin B. the mortality rate related to CR-AB infection was 45.4%, and ventilator-associated pneumonia and bloodstream infections were the most frequent clinical manifestations.Conclusions: the presence of 3 clones among the CR-AB isolates suggests that cross-transmission was the main mechanism responsible for dissemination of OXA-23 producers. PFGE pattern A was genotypically similar to that of the first OXA-23-producing A baumannii clone identified in Curitiba in 1999. This clone persisted in the same hospital until April 2004. the presence of the bla(OXA-23)-like gene was the main mechanism associated with carbapenem resistance among the isolates studied.