CONICET | Buscador de Institutos y Recursos Humanos

Fluorescent Microscopy: A tool to detect reactive oxygen species in Staphylococcus aureus induced by compounds with antimicrobial activity Sol Romina Martíneza,b,Ines Albesa a,b, María Rosa Mazzierib, María Cecilia Becerra a,b. a IMBIV-CONICET, Instituto Multidisciplinario de Biología Vegetal, Ciudad Universitaria, X5000HUA Córdoba, Argentina Martinez; E-mail: martinezsolr@gmail.com b Departamento de Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina. Results obtained in our group showed that the generation of reactive oxygen species (ROS) induced by clinical antibiotics were higher in sensitive than in resistant strains [1]. The objetive of this work was to evaluate the generation of ROS in Staphylococcus aureus ATCC 29213 and methicillin-resistant S.aureus (MRSA) ATCC 43300 strains, promoted by antimicrobial compounds, Linezolid and a new sythesized compound, N-benzenesulfonyl 1, 2, 3, 4-tetrahydroquinoline (BS-THQ) [2]. The Minimum inhibitory concentration (MIC) was determined using the standard tube dilution method [3], 2,7- dichlorodihydrofluorescein diacetate was used as a monitor of intracellular ROS generation by fluorescent microscopy as a qualitative method [4], ROS were also detected by Nitro Blue Tetrazolium (NBT) assay as a quantitative method [5]. The generation of ROS in the sesitive strain was particulary higher than in the resistant one. BS-THQ at subMIC induced 15.63% and 2.76%, respectively, while Linezolid showed an increase of 18.43% and 4.63% by NBT assay. Figure 1 shows the results obtained by fluorescence microscopy. We conclude that the differences in ROS generation between strains could be attribute to a higher antioxidant capacity in the resistant strain. Moreover, the generation of ROS could be associated to the mechanism of action of the studied compounds.