Identificação por espectrometria de massa MALDI-TOF de Salmonella spp. e Escherichia coli isolados de carcaças bovinas

Abstract

RESUMO.-O objetivo deste trabalho foi introduzir a téc-nica de espectrometria de massa com fonte de ionização e dessorção a laser assistida por matriz e analisador de tempo-de-voo (MALDI-TOF) para incrementar o método tradicional microbiológico na detecção de Salmonella spp. The aim of this study was to introduce matrix-assisted laser desorption/ionization (MAL-DI) time-of-flight (TOF) mass spectrometry to improve the traditional microbiological method for the detection of Salmonella spp. and Escherichia coli in beef carcasses. Two hundred seventy samples from 90 beef carcasses were evaluated. The methodologies described in ISO 6579:2002 and in the Compendium of Methods for the Microbiological Examination of Foods were used for Salmonella spp. and E. coli isolation, respectively. MALDI-TOF analysis were performed on tryptone soya broth suspension isolates or directly from nutrient agar colonies, from the positive, inconclusive or negative biochemically tested samples for Salmonella and E. coli. Mass profiles were acquired on an Autoflex III SmartBeam MALDI-TOF mass spectrometer and the raw spectra were processed using the MALDI Biotyper software (Bruker Daltonics). According to the preliminary identification based on colony morphology and the biochemical reactions, seven isolates were positive for Salmonella spp. Through MALDI Biotyper these seven isolates were also classified as belonging to the genus Salmonella and further identified as S. enterica. Four isolates showing unusual phenotypic characteristics and inconclusive results in biochemical tests for Salmonella were identified as belonging to Citrobacter and Proteus genera after MALDI analysis. Regarding Escherichia coli, 37 were positive for species biochemical testing which MALDI Biotyper confirmed. MALDI-TOF methodology allowed rapid Salmonella spp. and E. coli identity confirmation and may be used to detect these microrganisms within bacterial isolates from beef carcasses.

Monitoring the Action of Aerosolized H2o2 and the Impact on Fungi and Bacteria in the Indoor Air of São Paulo Environments

“…and Stenotrophomonas spp.) have already been described as pathogens (BIER et al, 2017;BLAZEJEWSKI et al, 2015;BROOKE, 2012;CAMPOS et al, 2021;CHANG et al, 2013;HSUEH et al, 2002;IOSIFIDIS et al, 2013;RODRÍGUEZ-MEDINA et al, 2019;UDUMAN et al, 2002).…”

Improved MALDI-TOF MS Identification of Mycobacterium tuberculosis by Use of an Enhanced Cell Disruption Protocol

“…Upon addition of 1 μL of α-cyano-4-hydroxy-cinnamic acid (5 mg/mL) in a solution containing 50% acetonitrile and 2.5% trifluoroacetic acid ( v / v ), crystallization of the matrix–analyte mixture was accomplished after air-drying at room temperature. A total of 18 replicates of this crystallized mixture were analyzed in an Autoflex III Smartbeam mass spectrometer (Bruker Daltonics), as described in [ 20 ]. Briefly, mass spectra in the mass range between 2000 and 20,000 Daltons were acquired with source voltage IS1 20 kV, source voltage IS2 18.55 kV, lens voltage 8.80 kV, and an ion extraction delay time of 240 ns in positive linear mode.…”

IDENTIFICAÇÃO DE LEVEDURAS DO GÊNERO Candida ISOLADAS DE HEMOCULTURAS DE PACIENTES ONCOLÓGICOS E PESQUISA DE BIOFILME

“…Dentro do equipamento, as células fúngicas foram rompidas, suas proteínas ionizadas, formando assim partículas que foram aceleradas em tubo à vácuo e separadas por diferenças de tempo, de acordo com suas relações massa/carga. Ao término, foi gerado um resultado do espectro de massa das proteínas ribossomais de cada micro-organismo (PASTERNAK, 2012;GOULART et al, 2013;BIER et al, 2017). A identificação foi obtida ao confrontar esses espectros com o banco de dados do software (versão 4) integrado ao equipamento.…”

“…Contudo, apesar de demonstrarem resultados mais rápidos que os métodos tradicionais, demandam um elevado custo de implantação e mão de obra qualificada (LACROIX et al, 2014;PASTERNAK, 2012). Como alternativa, surgiu o MALDI-TOF, sigla para Matrix Associated Laser Desorption Ionization Time of Flight, técnica baseada no estudo proteômico dos microrganismos, especialmente de proteínas ribossomais (RAJENDRAN et al, 2016;BIER et al, 2017).…”