Effects of Flavonoids and Antibiotics Combination on Preformed Biofilms and Small RNA of Staphylococcus aureus

Antibiotic resistance of Staphylococcus aureus has considerably increased among non-clinical or asymptomatic individuals. The formation of biofilms denies antimicrobial access to its targets present on the surface and inside the cell. The present study tested the effect of the combination of flavonoids and antibiotics over the preformed biofilms of S. aureus. The eradication of the preformed biofilms was analyzed using the crystal violet method. It has shown that 2500 µg mL^-1 Rutin and 100 µg mL^-1 Erythromycin (MIC Concentration) combination efficiently reduced the growth of the cells, which were adhered to the surfaces forming the biofilms. Fluorescence microscopic analysis indicated that the Rutin and Erythromycin (MIC value) combinations could eradicate the preformed biofilm cells more efficiently than other combinations. We found that the flavonoids and antibiotics with MIC concentration show a significant effect over the preformed biofilms cells of S. aureus. In addition, the semi-quantitative real-time PCR analysis for the sRNAs under the treatment of Rutin and Erythromycin combinations showed that few small RNAs expression (SprF, SprG, ArtR, Teg49, Teg41, and RNAIII) are getting downregulated upon the treatment; but again recovers with the incubation time interval increases. Combinations have a significant effect on Teg49 where there is a very faint intensity of the band, but for other small RNAs, there is an irregular pattern on the gel image. It has been concluded that at the initial period of incubation, the combinations have an effect on all the sRNAs but once the incubation increases, the effects have been slowly decreasing. It has been concluded that the combination has been able to reduce the doubling time of S. aureus upon treatment. Whereas, the small RNAs used in the study can be further evaluated for expression profiling through qRT-PCT.