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Objective: This study assessed the effects of alpha-mangostin (AM) and citronella oil (CO) working alone or in combination against Propionibacterium acnes (P. acnes) and Staphylococcus aureus (S. aureus). Methods: The screening for antibacterial activity of AM and CO against P. acnes and S. aureus was carried out using the disk diffusion method. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of these two substances were determined using the broth microdilution method. The fractional inhibitory concentration indices (FICI) of a combination of AM and CO were obtained by checkerboard dilution assay. Results: The results showed that alpha-mangostin and citronella oil do indeed fight against P. acnes and S. aureus. The MICs and MBCs of AM against P. acnes and S. aureus were the same at 6.25 and 50 µg/ml, respectively. Both the MIC and the MBC of CO against P. acnes were 27.81µg/ml. The MIC and the MBC of CO against S. aureus were 112.13 and 224.25 µg/ml, respectively. The FICI of a combination of AM and CO against P. acnes and S. aureus were 2.00, indicating indifferent interaction with no additional inhibitory effect. Conclusion: AM and CO are very effective against P. acnes and S. aureus, nevertheless their effect when used together was indifferent from using alone. Further research may find that either or both of these substances combined with yet a different natural agent could provide synergy againstP. acnes and S. aureus.
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Objective To compare the efficiency of bacteria culture and PCR assays for detection of Staphylococcus aureus ( S.aureus) , Pseudomonas aeruginosa ( P.aeruginosa) and Klebsiella pneumoniae ( K.pneumoniae) in laboratory rats and mice.Methods Bacteria culture combined with biochemical identification and PCR assay were used to detect 78 SPF rats and 422 SPF mice and the results of the two methods were compared .Results All the 78 rats were negative .Of the 422 mice, the positive rate by culture was 7.11%(30/422), of which, 10 were S.aureus, 22 were P.aeruginosa, and 2 were K.pneumoniae.The positive rate by PCR was 7.58%(32/422), of which, 10 were S.aureus, 25 were P. aeruginosa, and 2 were K.pneumoniae.Conclusions The high sensitivity , rapid procedure and easy to operate of PCR assay makes it valuable for rapid bacteria diagnosis and large-scale screening in laboratory animals .
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A magnetoelastic Staphylococcus aureus (S.aureus) wireless sensor was fabricated to detect S.aureus in different liquid medium.After 0.2 mL bacteria with proper concentration was taken into the tes ting cuvette containing 2 mL liquid medium, the resonance frequency of magnetoelastic sensor changed with the bacteria growth.Via changing the concentration of beef extract and peptone, sensor had the most frequen cy response in culture medium CM2-2 incubated with 2 × 10~5 cells/mL S.aureus.The results indicated that this sensor can be used to determine S.aureus concentrations of 3 × 10~3 to 2×10~7 cells/mL in culture medium and 10~4 to 10~7 cells/mL in milk, with the detection limits of 10~3 cells/mL and 104 cells/mL, respectively.The sensor frequency shift was correlated to the logarithmic value of the S.aureus concentration, and the correlation coefficient was 0.98 in milk and 0.99 in culture medium.