| Objective:The objectives of the study were to evaluate the efficacy and safety of TCMAI which discovered from traditional Chinese medicine. Based on the antibacterial effect, the antibacterial mechanism of TCMAI was studied by electron microscope technique.Methods:Pathogenic bacteria for dairy cow mastitis from chengdu, mianyang and meishan were identified by methods of automatic microbe analytic system and sequence analysis of 16S rDNA, and susceptibility to 8 antimicrobial agents was determined by K-B method.In vitro agar plate diffusions was used in testing susceptibility to crude extract of 78 chinese medicines, antibacterial action of 4 Chinese medicines and TCMAI discovered. However, in vivo antibacterial activity of TCMAI was detected by mice infected by resistant staphylococcus aureus and escherichia coli, and clinical trial of dairy cow mastitis. The antimicrobial mechanism was processed by electron microscope technique and growth curves of S.aureus and E.coli. The availability of TCMAI was evaluated through analyzing antibacteria effect and clinical effect. The safety of TCMAI was evaluated through analyzing rabbit muscle stimulation test, acute toxicity test in mice, as well as the change of liver and renal function in cows with mastits.Results:120 strains pathogenic bacteria for dairy cow mastitis were obtained, and 87.5% isolates showed different degrees of resistance to 8 antibiotics. Among these 8 antibiotics tested, most bacteria showed higher resistance to penicillin(67.21%) and streptomycin(64.81%). Among these 78 Chinese medicines tested, Bistort rhizome, coptis chinensis, elsholtzia, magnolia officinalis, garden burnet and fructus chebulae showed higher antibacterial effect to pathogenic resistant bacteria from dairy cow with mastitis. Except for 3 strains maltophilia, TCMAI showed extremely strong antibacterial activity for 117 strains tested bacteria, and MIC was 0.26～8.17mg/ml. Moreover, for the mice infected by resistant S. aureus or E.coli, TCMAI had high protective capacity in dose-dependent manner if mice was given prevention medcine by muscular injection. On the basis of breast swelling and clinical mastitis history, and so on,26 quarters in 19 cows with clinical mastitis were treated with TCMAI by breast perfusion and muscular injection, and 13 quarters in 10 cows were treated with antibiotics. TCMAI therapy demonstrated cure rates at animal level and at quarter level was,89.47% and 88.46%, respectively. However, cure rates of antibiotic controls at animal level and at quarter level was 80.00% and 847.62%, respectively. In addition TCMAI could rapidly eliminate the breast swell caused by bacteria. LD50 of TCMAI was respectively 1.873g/kg and 0.442g/kg, as it were given into the mice by muscular injection and intraperitoneal injection. Low muscle stimulation showed that TCMAI could be used in injection. The results of study on antibacteiral mechanism suggested that TCMAI significantly prolonged retardation stage and decreased growth reproductive speed of S. aureus and E.coli. Cell content was gradually dissolved because of cell structure damaged, and lastly bacteria died of empty cell. In addition, reproductive mode of S. aureus was changed, It is that most binary fission was substituted by multiple division.Conclusions:For bovine mastitis caused by resistant and sensitive bacteria, TCMAI is extremely attractive candidates as therapeutic agents due to their wide spectrum of antimicrobial activity and mechanism of action. Further more, it has lower toxicity and higher safety.
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