ABSTRACT
Methicillin-resistant Staphylococcus aureus (MRSA) is a superbacterium, and when it forms biofilms, it is difficult to treat even with the first-line of antibiotic linezolid (LNZ). Reyanning mixture (RYN), a compound-based Chinese medicine formula, has been found to have inhibitory effects on biofilms. This study aims to explore the synergistic inhibitory effect and corresponding mechanisms of their (LNZ&RYN) combination on the planktonic as well as biofilm cells of MRSA. Broth microdilution and chessboard methods were employed for the determination of minimum inhibitory concentrations (MICs) and synergistic concentration of LNZ&RYN, respectively. The effect of the combined medication on biofilm and mature biofilm of MRSA were observed by biofilm morphology and permeability experiments, respectively. To unveil the molecular mechanism of action of the synergistic combination of LNZ and RYN, RT-PCR based biofilm-related gene expression analysis and ultra-high pressure liquid chromatography-time-of-flight mass spectrometry based endogenous metabonomic analysis were deployed. The results indicated that 1/16RYN as the best combined dose reduced LNZ (4 µg/ml) to 2 µg/ml. The combined treatment inhibited living MRSA before and after biofilm formation, removed the residual structure of dead bacteria in MRSA biofilms and affected the shape and size of bacteria, resulting in the improvement of biofilm permeability. The mechanism was that biofilm-related genes such as agrC, atlA, and sarA, as well as amino acid uptake associated with the metabolism of 3-dehydrocarnitine, kynurenine, L-leucine, L-lysine and sebacic acid were inhibited. This study provides evidence for the treatment of MRSA and its biofilms with LNZ combined with RYN.
ABSTRACT
In the previous research, our laboratory established a mouse model combining disease with syndrome of human coronavi-rus pneumonia with pestilence attacking the lung syndrome, based on the national traditional Chinese medicine clinical classification of Novel Coronavirus Infected Pneumonia Diagnosis and Treatment Plan. In this study, a mouse model combining disease with syndrome of human coronavirus pneumonia with pestilence attacking the lung syndrome was used to evaluate the effectiveness of Reyanning Mixture to provide animal experimental support for clinical application. Mice were divided into normal group, 229 E infection group, cold-dampness group, cold-dampness+229 E infection group(the model group), Reyanning high and low dose groups. The cold-dampness group, cold-dampness+229 E infection group, two Reyanning groups were given cold and damp stimulation for 7 days. On the 5 th day, the 229 E infection group, cold-dampness+229 E infection group, and two Reyanning groups were infected with HCoV-229 E virus. Reyanning was administered for 3 days, starting from the day of infection. Blood was collected on the 4 th day and the lung tissue was dissected to calculate the lung index and inhibition rate; flow cytometry was used to detect the percentage of T and B lymphocytes in peripheral blood; RT-PCR was used to detect the nucleic acid virus load in lung tissue; ELISA was used to detect motilin and gastrin in serum, and inflammatory factors TNF-α, IFN-γ, IL-6, IL-10 in lung tissue proteins. Reyanning Mixture could reduce the lung index(P<0.01) of coronavirus pneumonia mice with pestilence attacking the lung; it could significantly increase the percentage of CD8~+ T lymphocytes and CD4~+ T lymphocytes in peripheral blood of model mice(P<0.05, P<0.01). The low dose of Reyanning could effectively increase the percentage of total B lymphocytes(P<0.05), reduce virus load in lung tissue of model mice(P<0.01), reduce the levels of TNF-α, IFN-γ, IL-6, IL-10 in the lung tissue of model mice(P<0.01), reduce the content of motilin in the serum of model mice(P<0.01). Reyanning Mixture convey a better effect in treating coronavirus pneumonia mice with pestilence attacking the lung. It manifested obvious effects in improving lung lesions, enhancing the gastrointestinal function of mice, improving the autoimmune function of mice, and reducing the expression of inflammatory factors in vivo, which could provide evidences for clinical research.
