Study on antibacterial activity and mechanism of selenium glycyrrhiza polysaccharide,glycyrrhiza polysaccharide and their combined antibiotics against Streptococcus agalactiae in vitro
[Objective]To study the antibacterial activity and mechanism of selenium glycyrrhiza polysac-charide(SeGUP)and glycyrrhiza polysaccharide(GUP)against Streptococcus agalactiae in vitro,and determine whether the combination of them can enhance the antibacterial effect of antibiotics.[Methods]Antibiotics sensitive to Streptococcus agalactis were screened by drug sensitive paper.The minimum inhibitory concentra-tion(MIC),minimum bactericidal concentration(MBC)and joint inhibitory index(FICI)were measured by the minimum double dilution method and chessboard method;Mixed Streptococcus agalactis with 120,60,30 mg/mL SeGUP,GUP and antibiotics in equal amounts respectively were used to draw the bacterial growth rate dia-gram;Meanwhile,detection of alkaline phosphatase β-Galactosidase activity,protein content and intracellu-lar DNA concentration were studied to find the effects of SeGUP,GUP and combined antibiotics on bacterial cell membrane,cell wall and DNA;Finally,the effect of SeGUP,GUP and combined antibiotics on the bio-film formation of Streptococcus agalactis was detected by crystal violet staining.[Results]Streptococcus agalac-tis was moderately sensitive to SeGUP 480 mg/mL and GUP 480 mg/mL,and the diameter of the inhibition zone was 14.0 mm and 11.0 mm;Streptococcus agalactis is extremely sensitive to kanamycin hydrochloride,doxycycline hydrochloride,ceftriaxone sodium and florfenicol;MIC and MBC of SeGUP and GUP against Streptococcus pneumoniae were 120,240 mg/mL and 240,480 mg/mL respectively;The FICIs of SeGUP with kanamycin hydrochloride,doxycycline hydrochloride,ceftriaxone sodium,and florfenicol were 1.5,0.75,1,0.5,indicating that the relationship between SeGUP and kanamycin hydrochloride was irrelevant,the relation-ship between SeGUP and doxycycline hydrochloride,ceftriaxone sodium was additive,and the relationship be-tween SeGUP and florfenicol was synergistic.The FICIs of GUP with kanamycin hydrochloride,doxycycline hydrochloride,ceftriaxone sodium,and florfenicol were 1.5,1,1.5,0.75,The results showed that GUP had no relationship with kanamycin hydrochloride and ceftriaxone sodium,but additive relationship with doxycyc-line hydrochloride and florfenicol;SeGUP and GUP significantly inhibited the growth of bacteria,of which SeGUP 120 mg/mL had the strongest effect.The combination of SeGUP and GUP with doxycycline hydrochlo-ride,ceftriaxone sodium and florfenicol has enhanced the inhibition effect;SeGUP,GUP and combination of antibiotics could significantly increase alkaline phosphatase(AKP)β-Galactosidase(β-gal),protein content(P<0.05),significantly reduced the content of intracellular DNA(P<0.05),significantly inhibited the formation of biofilm of Streptococcus agalactis(P<0.05)[Conclusion]SeGUP can significantly inhibit Strep-tococcus agalactis by damaging the integrity of bacterial cell wall and cell membrane and affect DNA content,and its antibacterial activity is superior to that of GUP.The combination of SeGUP and antibiotics can enhance the antibacterial activity of antibiotics,and its effect is stronger than those of SeGUP,GUP and antibiotics used alone.
万方数据
维普
