四种藏兽医药用植物和屎肠球菌联用对大肠杆菌E6生物被膜的影响OA北大核心CSTPCD

Semi-quantitative modified crystal violet staining and microbroth dilution method were used for examination of biofilm-forming ability of 152 Escherichia coli isolates and drug susceptibility of 12 commonly used antibiotics.Meanwhile,chemosensitivity test was performed to evaluate the combined bactericidal activity of the sequential solvent fractions(methanol,dichloromethane,ethyl acetate and petroleum ether)of four Tibetan veterinary medicines(Spenceria ramalana Trimen,Thalictrum delavayi Franch.,Gentiana sino-ornata Balf.f.,Lonicera rupicola Hook.f.& Thomson),ethyl acetate extract of two Enterococcus faecium isolates and antibiotics with high resistance rates(Chloramphenicol,Oxytetracycline,Ampicillin and Sulfamethoxazole)for selected 10 multi-drug resistant E.coli strains(E1-E10).Lastly,E.coli strain E6 with moderate biofilm forming ability was chosen for examine biofilm scavenging effect of these drug combinations.The results showed that most of the 152 E.coli isolates had the moderate or no biofilm-forming ability.Drug resistance rates were all over 90％to chloramphenicol,sulfamethazine,oxytetracycline,ampicillin and sulfamethoxazole and lower than 50％to difloxacin,ciprofloxacin,amikacin,cefotaxime,tobramycin and ceftriaxone,among which these strains were more susceptible to Amikacin as the drug resistance rate was only 19.90％.The MIC ranges to E.coli strains E1-E10 were 3.93-15.63 mg/mL for methanol extract from Spenceria ramalana Trimen,3.93-31.52 mg/mL for ethyl acetate extract from Thalictrum delavayi Franch.,7.81-15.63 mg/mL for methanol extract from Gentiana sino-ornata Balf.f.,7.81-31.52 mg/mL for ethyl acetate extract from Lonicera rupicola Hook.f.&Thomson,0.42-13.38 mg/mL and 0.45-3.63 mg/mL for ethyl acetate extracts from Enterococcus faecium S16 and S17,and respectively.The combinations of the sequential solvent fractions of the four Tibetan veterinary medicinal plants,ethyl acetate extract of Enterococcus faecium and antibiotics with high resistance rates showed different effects.At the MIC concentrations,all the drugs used in combination performed stronger biofilm scavenging effect than single use.The biofilm inhibitory rates of the combined use of the ethyl acetate extracts from Lonicera rupicola Hook.f.& Thomson and Thalictrum delavayi Franch.with oxytetracycline and ampicillin were 48.92％,42.58％and 48.58％,47.84％,which were higher than other drug combinations.In conclusion,the combined uses of four selected Tibetan medicinal plants,probiotics and antibacterial agents might provide a possibility to resolve drug resistance and biofilm formation of E coli isolated from Tibetan pigs and chickens.