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Determination of the susceptibility profile of isolates of Candida from blood culture bottles is extremely important for correctly guiding patient pharmacotherapy. The aim of this study was to compare the results of analysis of Candida isolated directly from blood culture bottles by the VITEK MS MALDI-TOF identification system and the fluconazole disk diffusion assay with those of standard identification methods. Testing directly from the bottle allowed results 24 to 48 hours quicker than the standard method. There was a categorical agreement of 51.64% (47 of 91 samples) between the results of analysis directly from the bottle and analysis by the standard method. Regarding species identification, there was 96.15% agreement for Candida parapsilosis (25 of 26 samples). Categorical agreement between the rapid and standard disk diffusion methods was 95%, and the agreement between the rapid disk diffusion method and the broth microdilution method was 97%. Only minor errors in the rapid method were observed: 3 (5%) in the standard disk diffusion method and 2 (3%) in the broth microdilution method. Our study concluded that the rapid disk diffusion method for fluconazole is a fast, easy, reproducible, and consistent method. Its timely implementation for testing antifungal agents in the clinical microbiology laboratory can help reduce profile release times, thus helping to determine the most appropriate antifungal treatment.

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IntroductionInfections caused by multidrug-resistant microorganisms have become increasingly common in hospital environments around the world. Gram-negative bacilli stands out among multidrug-resistant bacteria mostly due to the production of carbapenemase enzymes which lead to resistance to most β-lactam antibiotics including the carbapenems. As a consequence, polymyxins have been reintroduced in the clinic as a last resort to treat infections caused by Gram-negative bacilli resistant to carbapenems. However, the only reliable method to evaluate the susceptibility to polymyxins is the broth microdilution, a laborious and time-consuming technique. Among infections caused by multidrug-resistant bacteria, bloodstream infections are the most worrisome as they can lead to sepsis and septic shock with high mortality rates.ObjectiveConsidering the severity of sepsis and the need for a treatment guided for the susceptibility test in vitro, this work aimed to evaluate a rapid method of polymyxins susceptibility either from colonies grown on agar or directly from positive blood culture bottles using the technology of MALDI-TOF.MethodsThe method was based on the “direct on target microdroplets growth assay” (DOT-MGA) originally developed by Idelevich and collaborators with some modifications (Adapted DOT-MGA). Isolates of Enterobacterales and non-fermenting Gram-negative bacilli resistant to carbapenems were obtained from patients attending a tertiary care hospital in southern Brazil and tested as follows: 122 isolates from colonies grown on agar plates and 117 isolates directly from spiked positive blood cultures.ResultsThe adapted DOT-MGA presented 95 and 100% of categorical agreement considering the colonies grown on agar plates and directly from positive blood cultures, respectively.DiscussionThe adapted DOT-MGA test proved to be a reliable technique to evaluate the susceptibility to polymyxins to be used in microbiology laboratories with the MALDI-TOF equipment.

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Introdução A resistência antimicrobiana, especialmente em patógenos Gram-negativos clinicamente importantes, atingiu um nível crítico, com o surgimento de resistência a quase todos os antibióticos disponíveis. Acinetobacter baumanii (CAb) estão entre os principais patógenos causadores de infecções hospitalares, especialmente em Unidades de Terapia Intensiva (UTIs). De acordo com a Agência Brasileira de Vigilância Sanitária (ANVISA, 2013) mais de 80% dos CAb de UTIs eram resistentes aos carbapenêmicos (CRAB). Neste contexto, o CRAB tem sido endêmico e as polimixinas são terapia de primeira linha para o tratamento de infecções causadas por este patógeno. Após o surgimento da pandemia de COVID-19, observamos um aumento das taxas de incidência de infecções por CRAB na nossa instituição. Objetivo Avaliar o impacto da pandemia de COVID-19 na concentração inibitória mínima (CIM) à polimixina B (PMB) dos isolados CRAB de amostras clínicas de pacientes atendidos no Hospital de Clínicas de Porto Alegre. Métodos Um estudo retrospectivo foi realizado para avaliar dados clínicos e microbiológicos de pacientes com cultura positiva para CRAB de janeiro de 2019 a Outubro de 2021 A identificação bacteriana foi realizada pelo sistema Vitek©MS (bioMérieux, França) e a sensibilidade à PMB foi realizada pelo método de microdiluição em caldo de acordo com BrCAST. Resultados: Foi obtido um total de 299 isolados de CRAB (2019, n = 25; 2020, n = 164; 2021, n = 109). Em 2019, 36% das amostras foram provenientes do trato respiratório inferior (aspirado traqueal/escarro/LBA). Já em 2020 e 2021, 74% dos CRABs foram isolados desse sítio. O percentual de sensibilidade de CRAB à PMB em 2019, 2020 e 2021 foi de 92%, 92,7% e 91,7%, respectivamente. A CIM para PMB variou de 0,25-32 μg/mL e CIM50/CIM90 foram 0,5 μg/mL/2,0 μg/mL, respectivamente em todos os períodos analisados. Em 2019, 2021 e 2021 apenas 2 (8%), 12 (7,3%) e 9 (8,3%) isolados CRAB apresentaram resistência à PMB (MIC ≥ 4 μg/mL). Não houve diferença estatisticamente significativa na variação da CIM para PMB em isolados de CRAB nos períodos analisados. Conclusão A prevalência de resistência à polimixina B em isolados CARB, bem como os valores de CIM50 e CIM90, ainda se mantém em níveis baixos na nossa instituição, mesmo após a pandemia de COVID-19. O acompanhamento da suscetibilidade do Acinetobacter baumannii é importante para o monitoramento da resistência e conhecimento da epidemiologia local.