Identificación rápida de microorganismos de frascos de hemocultivos por espectrometría de masas: Comparación de 2 procedimientos diagnósticos / Rapid identification of microorganisms by mass spectrometry in a blood culture system: Comparison of two procedures

La identificación rápida de microorganismos es crítica, en especial en pacientes sépticos hospitalizados. La espectrometría de masas conocida como matrix-assisted laser desorption/ionization time-of- flight mass spectrometry (MALDI-TOF MS) permite la identificación directa desde botellas de hemocultivos positivos en forma rápida y sencilla. Este estudio evaluó el desempeño del procedimiento basado en el sistema MALDI Biotyper que utiliza el kit comercial MALDI Sepsityper de Bruker Daltonics (en adelante, MS) frente a uno artesanal (en adelante, HF). Se procesaron 840 botellas de hemocultivos positivos con HF y 542 de estas fueron evaluadas también con MS. Se logró la identificación de los microorganismos en 670 (79,76 %) y 391 (72,14 %) botellas, respectivamente (p = 0,0013). Se demostró la efectividad de ambos procedimientos para la identificación de microorganismos desde frascos de hemocultivos positivos. Sin embargo, el procedimiento HF fue superior al MS, en especial frente a bacterias gram positivas.

Rapid identification of microorganisms is critical in hospitalized infected patients. Blood culture is currently the gold standard for detecting and identifying microorganisms causing bacteremia or sepsis. The introduction of mass spectrometry by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) in microbiology laboratories, especially in microorganisms growing in blood culture bottles, provides rapid identification. This study evaluates the performance of the Maldi Sepsityper Biotyper procedure (hereinafter, MS) compared to that of an in-home method (hereinafter, HF). Eight hundred and forty (840) positive blood culture bottles were processed using the HF procedure, 542 of which were also processed using MS. The organisms were identified in 670 (79. 76 %) and 391 (72. 14 %) bottles respectively (p = 0,0013). This study demonstrates the effectiveness of both procedures for identifying microorganisms directly from positive blood culture bottles. However, the HF procedure proved to be more effective than MS, especially in the presence of Gram positive organisms.

Synthesis and biological evaluation of some new coumarin derivatives as antimicrobial agents

A series of new 7-[2-[3-alkyl/aryl-4-arylthiazol-2[3H]-ylidene]hydrazono]propoxy]-4-methyl-2H-chromen-2-ones, [6-9a-e], was prepared by the reaction of appropriate N-alkyl/aryl-2-[1-[4-methyl-2-oxo-2H-chromen-7yloxy]propan-2-ylidene]hydrazine carbothioamides [4a-d] and phenacyl bromides [5a-e]. The purity of all new compounds was checked by TLC and elucidation of their structures was confirmed by IR, [1]H NMR, and mass spectrometry along with elemental microanalyses. All the target compounds were evaluated for their possible antimicrobial activity. Most of the tested compounds showed weak to moderate antibacterial activity against most of the bacterial strains used in comparison with gatifloxacin as a reference drug. The most active compounds were 6b, 6c, 7b, 8b, 8c, and 9c against B. cereus, E. coli and S. marcescens. Results of antifungal activity revealed that all compounds showed weak to moderate activity against S. brevicaulis, while ketoconazole as a reference drug was completely inactive. Compounds 6a, 6b, 6c, 6e and 7b were even more active than ketoconazole against F. oxysporum

Utilizaçäo de espectrometria de massa para o estudo do metabolismo protéico e aminoacídico, em medicina / Stable isotope spectrometry to study human protein and amino acid metabolism

O desenvolvimento e uso de técnicas laboratoriais, envolvendo espectrometria da massa, permitiram que os isótopos estáveis pudessem ser utilizados na avaliaçäo do metabolismo aminoacídico e protéico, em seres biológicos. Assim, medidas precisas de enriquecimento isotópico, ao nível 3-6 por cento além do basal, após infusäo de 13C-, 15N- ou de 2H2-aminoácido, tornaram possível realizar a avaliaçäo das interrelaçöes metabólicas protéicas no organismo, in vivo. O método pode ser considerado pouco invasivo, sendo necessário, geralmente, coleta de ar expirado e sangue periférico, para determinaçäo de substratos na concentraçäo em torno de nanomolar. Desta maneira, períodos de infusäo isotópica, de 4-6 horas, de 13C-leucina, permitem estimativa do metabolismo protéico corpóreo total, pela medida direta da oxidaçäo, via determinaçäo do 13CO2, no ar expirado, e da 13C-Leu ou seu metabólito, 13C-KIC, no sangue, assim como estimativa da degradaçäo e síntese protéica. Mais recentemente, o advento de nova técnica, ou seja, a da associaçäo de combustäo da amostra à cromatografia e espectrometria, tornou o método mais sensível, sendo possível a determinaçäo de substrato, marcado em amostras diluídas por um fator mínimo de 10. O método também permite o estudo da interrelaçäo do metabolismo protéico com o de hidrato de carbono e lipídeo, quando aplicado a aminoácidos, essenciais ou näo, associados a glicídios e triglicerídeos.