Antibacterial and anti-biofilm properties of carvacrol alone and in combination with cefixime against Escherichia coli.

BACKGROUND: Plant-derived compounds can be used as antimicrobial agents in medicines and as food preservatives. These compounds can be applied along with other antimicrobial agents to strengthen the effect and/or reduce the required treatment dose. RESULTS: In the present study, the antibacterial, anti-biofilm and quorum sensing inhibitory activity of carvacrol alone and in combination with the antibiotic cefixime against Escherichia coli was investigated. The MIC and MBC values for carvacrol were 250 µg/mL. In the checkerboard test, carvacrol showed a synergistic interaction with cefixime against E. coli (FIC index = 0.5). Carvacrol and cefixime significantly inhibited biofilm formation at MIC/2 (125 and 62.5 µg/mL), MIC/4 (62.5 and 31.25 µg/mL) and MIC/8 (31.25 and 15.625 µg/mL) for carvacrol and cefixime, respectively. The antibacterial and anti-biofilm potential effect of carvacrol confirmed by the scanning electron microscopy. Real-time quantitative reverse transcription PCR revealed significant down-regulation of the luxS and pfs genes following treatment with a MIC/2 (125 µg/mL) concentration of carvacrol alone and of only pfs gene following treatment with MIC/2 of carvacrol in combination with MIC/2 of cefixime (p < 0.05). CONCLUSIONS: Because of the significant antibacterial and anti-biofilm activity of carvacrol, the present study examines this agent as an antibacterial drug of natural origin. The results indicate that in this study the best antibacterial and anti-biofilm properties are for the combined use of cefixime and carvacrol.

Investigation of the target genes of BLV miRNAs and the expression levels of miR-B4-3p and miR-B2-5p in cattle infected with Bovine Leukemia Virus.

Bovine Leukemia Virus (BLV) is an oncogenic retrovirus of the genus Deltaretrovirus. The genome of BLV encodes a cluster of 10 mature microRNAs (miRNAs). Considering the importance of miRNAs in regulating gene expression, it seems that each of the miRNAs of BLV plays a vital role in the process of pathogenesis and tumorigenesis of the virus. First, sequences of each of the miRNAs of BLV were selected and downloaded from the miRBase database. The sequences were then investigated using TargetScan and miRWalk to identify target genes of each of the mature miRNAs of the virus. Second, the expression levels of the two miRNAs with the highest number of target genes in B lymphocytes and lymphoid tissues were evaluated using qPCR and were compared between cattle with different forms of BLV infection: PL form was compared to aleukemic (AL) form (Group 1) and BLV+ with normal lymph nodes were compared to lymphosarcoma form (Group 2). We identified a total of 1595 target genes of the micro RNAs. The miRNAs with the highest target genes included miR-B4-3p with 760 and B2-5p with 102 target genes. In the second phase, miRNA expression in BLV-infected animals was investigated. The Fold Change (FC) values for miR-B4-3p and miR-B2-5p in group 1 were 22 and 67, respectively. In the second group, the FCs for miR-B4-3p and miR-B2-5p were 47 and 133, respectively. The expression was significantly higher in persistent lymphocytosis (PL) cattle in group one and lymphosarcoma cattle in group two.