| Endometritis is a common postpartum disease of dairy cows.Cows with endometritis usually suffer from decreased milk yield,prolonged pregnancy,and even infertility and elimination,which brings serious economic losses to the dairy industry in China and even the world.Microorganisms contamination in the uterus is responsible for endometritis.Trueperella pyogenes is an opportunistic pathogen that can cause infection in uterus and endometritis.In this study,we collected 105 uterine discharge samples from dairy cows with endometritis in 11 herds in the northwest of China and recovered 50 T.pyogenes isolates.Then we detected 8 virulence genes(plo,fim A,fim C,fim E,fim G,nan H,nan P,and cbp A)by PCR and analyzed the antibiotic-resistant phenotype and genotype,as well as the ability of biofilm formation.This knowledge will help us to further understand the pathogenicity of T.pyogenes and provide some guidance for clinical treatment and comprehensive prevention and control of endometritis in the northwest of China.1.We collected 105 uterine mucus samples of dairy cows with endometritis from 11 herds from Gansu,Ningxia,and Shaanxi provinces.Then identified the main pathogens,including 50(26.7%)T.pyogenes isolates,37(19.8%)Escherichia coli isolates,34(18.2%)Streptococcus spp.strains,19(10.2%)Bacillus spp strains and 47(25.1%)other strains.Among them,T.pyogenes strains were the highest proportion among all types of pathogenic bacteria,and the average detection rate was 47.6%.2.In this study,8 known virulence genes were detected in 50 T.pyogenes isolates by PCR.The result showed that all strains carried plo,fim A,fim C,and nan P.The fim E,fim G,nan H and cbp A were found in 49(98.0%),5(10.0%),47(94.0%)and 39(78.0%)strains,respectively.Besides,one of the most popular virulence gene profiles was plo/fim A/fim C/fim E/nan P/nan H/cbp A in our study and 62.0%of strains were classified in this type.3.Micro broth dilution method was used to determine the MIC(minimum inhibitory concentration)values of 8 antibiotics against 50 T.pyogenes isolates.And according to the breakpoints of 7 antibiotics,all the isolates in this study were sensitive to penicillin and rifampicin,and the MIC values were less than 0.063 ?g/m L and 0.008 ?g/m L,respectively.Ninety-two point zero percent of the isolates were sensitive to levofloxacin with the MIC range of 0.5 ?g/m L to 8 ?g/m L.Seventy-six point zero percent of the isolates were sensitive to erythromycin with the MIC range of 0.016 ?g/m L to 4 ?g/m L.And72.0% of the isolates were sensitive to clindamycin with the MIC range of 0.063 ?g/m L to 4 ?g/m L.Also,68.0% and 74.0% of isolates were resistant to tetracycline and gentamicin.MIC values were0.063?16 ?g/m L and 0.5?32 ?g/m L,respectively.The MIC of ceftiofur was from 0.25 ?g/m L to 2?g/m L.4.By PCR detection,the proportion of strains carrying tetracycline resistance gene tet(W)was80.0%.Twelve point zero percent of strains were erythromycin-resistant gene erm(X)positive and no erm(B)gene was detected in this study.It was found a high correlation between resistance phenotype and genotype of tetracycline and erythromycin.5.The crystal violet staining method was used to quantitatively detect the biofilm formation ability of 50 T.pyogenes strains.The results showed that 64.0% of isolates could form the biofilm,and 50% of the strains had weak ability to form biofilm.The results of this study have important reference significance for the rational use of antibiotics in the clinical treatment of endometritis,reducing the emerge of drug-resistant strains,improving the clinical treatment effect and further exploring the pathogenicity and drug resistance mechanism of T.pyogenes. |
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