Navegando por Palavras-chave "Resistência Bacteriana No Meio Ambiente"

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    Caracterização fenotípica e molecular de isolados de Acinetobacter spp. Produtores de oxa-carbapenemases provenientes de diferentes reservatórios
    (Universidade Federal de São Paulo (UNIFESP), 2019-05-30) Barbosa, Ana Clara Narciso [UNIFESP]; Gales, Ana Cristina [UNIFESP]; Martins, Willames Marcos Brasileiro da Silva [UNIFESP]; http://lattes.cnpq.br/9774751756469078; http://lattes.cnpq.br/8402272715765172; http://lattes.cnpq.br/6494873090725255; Universidade Federal de São Paulo (UNIFESP)
    The genus Acinetobacter comprises a set of bacterial species capable of causing infections in both humans and animals. High rates of carbapenem resistance have been reported among Acinetobacter spp. from worldwide, usually due to the production of carbapenemases. We evaluated isolates of Acinetobacter spp. producers of CHDL recovered from different reservoirs (human and animal). The Acinetobacter spp. isolated from birds were obtained from a surveillance study performed in collaboration with the São Paulo Zoo. Choanal and cloacal swabs from Anseriformes birds (captive and migratory) recovered at the São Paulo Zoo lake (Attachment 3). Subsequently, a microbiological screening was performed to select gram-negative bacilli with reduced sensitivity to carbapenems (Attachment 4). Those identified by MALDI-TOF MS as Acinetobacter spp. were selected. The results of this study were presented in two manuscripts: Article 1 - Published in November 2017 in the journal Antimicrobial Agents and Chemotherapy (Impact Factor: 4,302). The OXA-58-producing A. seiferttii AC12.1 isolate was recovered from the C. melancoryphus microbiota. The isolate showed high MICs for most β-lactams, amikacin, and polymyxin B. The quinolones, tigecycline, gentamicin, minocycline, and sulfamethoxazole/trimethoprim showed good in vitro activity against this isolate. AC12.1 showed a PFGE pattern and a plasmid profile identical to that of isolate previously identified from a patient diagnosed with bloodstream infection in the 1990s. In both bacterial isolates, a ~59 Kb plasmid was detected carrying blaOXA-58 gene, which has been not transferred by electroporation assays. Isolate AC12.1 was subjected to genetic analysis by walking sequencing and revealed that an ISAba825 was inserted upstream of blaOXA-58. Both structures were flanked by two copies of truncated ISAba3. Article 2 - Not submitted yet. The objective was to characterize isolates of OXA-72 producing A. baumannii recovered from captive and migratory Anseriformes from São Paulo Zoo. Additionally, we compare clinical isolates recovered from patients hospitalized at Hospital São Paulo between 2000 and 2017. All isolates were highly resistant to carbapenems and showed high MICs for other β-lactams. In contrast, all isolates showed low MICs for polymyxin B, minocycline, and tigecycline. Two clonal patterns were determined by PFGE (A and B). The pattern A was composed by human and Anseriformes isolates, and pattern B was composed exclusively by human isolates. According to the clonal pattern, distinct subtypes of both groups were selected for MLST (PubMLST) experiments. Clonal complex 79 was the most frequent one observed. All isolates carried a ~16 Kb plasmid with, which was transferred to ATCC19606 by electroporation. The plasmid location of blaOXA-72 was confirmed. Two representative isolates that showed the same genetic characteristics; however, recovered from different reservoirs were selected for whole genome sequencing by the Illumina MiSeq. Analyzes demonstrate that both isolates had the same 16,673 bp plasmid called pAC1-BRL. In addition to blaOXA-72, a macrolide resistance gene was detected, both flanked by the XerC / XerD recombination sites. Comparison with genetically related plasmids showed that pAC1-BRL is related to plasmids detected from different countries encoding different OXAs-carbapenemases. Interestingly, some plasmids considered genetically related did not carry CHDL-encoding genes. We conclude that the results presented in this dissertation expose information about the relationship of birds present in the FPZSP with the dissemination of microorganisms of clinical importance. This relation elucidates important genetic characteristics in these isolates and evidence a possible network of contamination / dissemination among different environments.
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    Caracterização molecular dos mecanismos de resistência às polimixinas em isolados ambientais de Klebsiella variicola
    (Universidade Federal de São Paulo (UNIFESP), 2020-05-28) Pinto, Michael Henrique Lenzi [UNIFESP]; Gales, Ana Cristina [UNIFESP]; Universidade Federal de São Paulo
    Polymyxins are cationic compounds used as last-resort treatment of multiresistant gram-negative bacteria. The bactericidal action of polymyxins occurs when there is an electrostatic interaction between the positive charge of polymyxins and the negative charge of lipid A. The return to use of polymyxins in clinical treatment and continued use in veterinary medicine has caused an increase in reports of bacteria resistant to these compounds, especially in the hospital settings. Lipid A modification is the main mechanism of resistance polymyxin resistance phenotype. These modifications can be mediated chromosome via two-component systems (TCS), or via mobile elements MCR protein. This study aims to investigate isolates of polymyxins resistant Klebsiella variicola from migratory birds and to characterize the mechanisms responsible for this phenotype. A total of 339 gram-negative microorganisms were selected from of environmental samples from migratory birds collected at the Zoo of São Paulo in 2012. The polymyxin resistant gram-negative isolates from natural sources were identified by MALDI-TOF MS. Bacterials belonging to the same species K. variicola were analized to genetic similarity analysis by PFGE. After, the susceptibility profile to the other antimicrobials was determined by the dilution agar technique and interpreted following EUCAST/BrCAST guidelines. K. variicola isolates were to submit to detection of polymyxin resistance factors by phenotypic and molecular technique, followed by membrane load analysis. To the characterization the genes responsible for polymyxin resistance, the Whole Genome Sequencing (WGS) was performed by Illumina MiSeq methodology. Three polymyxins resistants K. variicola isolates (M14, M15 and M50) were identified. Among these, it was possible to visualize two different clonal groups, where M15 is a subclone of M14 and M50 a different clone. MLST analysis showed that M14 and M15 belong to ST137 and M50 to ST167. Susceptibility tests have shown that the three isolates are susceptible to all antimicrobials tested except polymyxins. There was no detection of mcr gene variants in these isolates. WSG analysis demonstrated mutations that cause protein change in genes responsible for polymyxin resistance in K. pneumoniae (mgrB, phoQ and pmrB). These same genes showed high transcriptional levels observed in the qRT-PCR demonstrating correlation with polymyxin resistance in the three isolates.