Selection Of Prescriptions From Traditional Chinese Medicine And Antibacterial Activity Of Escherichia Coli From Different Sources

Avian colibacillosis is one of the bacterial diseases,which seriously affects the poultry industry.The prevention and treatment of avian colibacillosis mainly rely on antibiotics,however,Escherichia coli(E.coli)develops resistance to drugs very easily,which then could be transmitted between human and animals,causing great harm to human health and public health safety.The discovery of deadly E.coli and the continuous reports of multi-drug-resistant strains have showed the alarm for the world.Thus,many countries have prohibited the long-term addition of antibiotics in animal feed,and searching for antibiotic replacements presents its urgency.Traditional Chinese herbs,as materials of Traditional Chinese Medicines(TCMs)are widely used in the treatment of diseases.They have the synergistic and additive relationship in terms of antibacterial efficacy,and their antibacterial effects vary due to isolates differences of E.coli.In order to clarify the relationships between antibacterial effects of TCMs and isolates of E.coli,the present paper studied the antibacterial effect of single-TCM and the TCMs prescriptions based on the characteristics(the carrying patterns of drug-resistance genes and virulence genes,and phylogenetic group)of E.coli isolates from different sources.The effects and the relationships between the characteristics of the isolates and the antibacterial effect of the TCMs were discussed in order to lay a theoretical foundation for the study of antibacterial therapy of TCM.First of all,E.coli was isolated and identified respectively from chicken livers at Farmers Market in Kunming City in this study,the budgerigar feces at the Bird and Flower Markets in Kunming City,the peacock feces of Kunming Zoo.The carrying rates of the 12 virulence genes and 22 drug resistance genes were examined.Secondly,30 strains of E.coli were selected according to the characteristics of isolates(including preserved pathogenic strains)from different sources,and the minimum inhibitory concentration(MIC)of the alcohol extracts of 18 kinds of TCMs was measured by two times dilution method.The checkerboard method was used to determine the combination effects of the two randomly combined TCMs,and two kinds of prescriptions from TCM were proposed.Finally,the relationship between the numbers and patterns of genes,the phylogenetic groups and the bacteriostatic effects of TCMs was analyzed.The findings are as follows:In this study,613 strains of bacteria were isolated and 225 strains of E.coli were identified finally.The virulence gene detection of isolates showed that the highest detection rate of traT gene was 99.67%,the lowest detection rate of papC gene was 20.13%,and the detection rates of tsh,papC,and cvaC virulence genes were below 60.00%,the detection rates of the other virulence genes were above 60%.The detection rates of virulence gene of E.coli from different sources were different.The rates of virulence genes of isolates from chicken livers were higher than that of fecal isolates,and the rates of isolates from diseased chicken livers were higher than that of isolates from chicken livers at farmers' markets(except for papC gene).The tests of drug resistance genes in isolates showed that the detection rates of two OXA and SHV resistant genes were less than 40%,and the rates of other genes were all above 40%.The highest detection rate of Gyra(QRDR)gene was 99.34%.The lowest rate of SHV gene was 11.55%.The detection rates of drug resistance genes of E.coli from different sources were different.Except for two kinds of OXA and SHV genes,the rates of other resistant genes were the highest in the isolates from infected chicken livers.The rates of 50% of drug resistance genes were the lowest among the peacock isolates.The bacteriostatic effects of 18 kinds of TCMs showed that the bacteriostatic effect of the 6 TCMs(Fructus Chebulae,Radix Sanguisorbae,Fructus Mume,Pericarpium Granati,Fructus Aurantii,Aloe Vera)were better.The combination effects of TCMs showed that TCMs presented synergistic and additive relationship when combined with two randomly,say,Fructus Schisandrae Chinensis,Fructus Mume,Fructus Aurantii,Fructus Chebulae,Pericarpium Granati.The best combination effect was found when Fructus Aurantii and Fructus Mume was tested.The additive or irrelevant relationships were obtained when Radix Pulsatillae,Cortex Fraxini,Radix Sanguisorbae,Fructus Aurantii,Aloe Vera was combined randomly.The best combination effect was found when Radix Sanguisorbae and Cortex Fraxini was tested.Two kinds of self-formulated TCM prescriptions were studied by Oxford cup method and drug plate dilution method.The results showed that the antibacterial effect of the first prescriptions was better,the inhibition zone diameters was 22.48 mm,and the minimum inhibitory concentration was 3.25 mg/mL.The results of correlation analysis showed that when the isolates carried more virulence genes and drug-resistant genes,the TCMs had a better inhibition or killing effect against associated isolates,otherwise the TCMs had a poor effect.As far as the dominant gene carrying patterns is concerned,the TCMs also has better inhibition or killing effect on these strains.There was no correlation between the phylogenetic groups of isolates,the number of virulence genes,the number of drug resistant genes and the bacteriostatic effect of the TCMs.The results in this study established a good foundation for the further study of the antibacterial effects of TCMs,also provided reference and basis for the development and utilization of prescriptions from TCMs.