| Rhodococcus equi is a Gram-positive facultative intracellular pathogen.Pneumonia caused by R.equi is a major cause of disease and death in foals.Purulent bronchopneumonia is the main clinical symptom,and it usually occurs in foals less than6 months old.R.equi is worldwide distribution and causes seriously affects of the development of the breeding industry and significant economic losses.As a zoonotic pathogen,R.equi not only impends the breeding of horses and the development of horse industry,but also threatens human health.However,there are few studies on the epidemic and bacterial characteristics of R.equi in China.Therefore,to provide the necessary reference for the prevention and treatment of R.equi in China,aerosol bacterial community from horse farm in Guangdong province and epidemiology of R.equi in soil of nine cities nation wide were investigated,and the physicochemical characteristics,drug sensitivity and virulence associated gene of the R.equi isolated strain were charactorized.Firstly,the composition of bacterial community and R.equi in the air of the stable were investigated via illumine-based analysis.The genomes of the samples were purified,amplified and sequenced through Illumina Miseq PE250.Taxonomic analysis of the OTU values via RDP classifier Bayesian algorithm,the community composition of each sample was analyzed at the Genus level.The results showed that the air samples in March,June and December belong to different clusters.The air samples in March and June belong to the same branch,while in December,they belong to one branch and the diversity index is the highest and microbial composition is unique in December.While the diversity and richness of stable aerosol microorganisms in December were significantly higher than that of other months,the richness of pathogenic organisms was relatively low.Most possible pathogenic genus were found in March and June,they were genus such as bacillus,streptococcus,pseudomonas,and corynebacterium etc.Ventilation and hygiene of stables are relatively poor in winter and intestinal inherent flora will also cause infection when immunity is low.Thus,attention should be paid to ventilation and sanitation in winter.In addition,the richness of the Rhodococcus in June was higher than that of other seasons,suggesting that there might be a high risk of R.equi infection in June.Thus,attention to regularly disinfection of the farm should be paid more in June.Secondly,the epidemiology of R.equi in soil from horse farms in China were investigated by an optimized and improved colony immunoblot test.R.equi was observed widespread in China,with average number of R.equi as 10~6 CFU per gram soil.The distribution of R.equi in the soil was related to horse activities,but not to season,geographical location and other factors.Therefore,attention should be paid to the cleaning and disinfection in the horse active area regularly.Finally,57 R.equi strains were isolated from the soil of horse farms by NANAT selective culture.Only one was virulent R.equi.Macrolide drug resistance in the isolates was first observed in mianland China,with corresponding resistance genes erm(46).All the tested strains with a rifampicin MIC less than 0.0625?g/mL and no Rifampicin resistant strains exhisted.In addition,differ from findings in other countries;all isolates in China contained the virulence-associated protein E(vapE)gene and the positive rate was 100%,which is rarely investigated.Further investigation of the relation of the vapE and the pathogenicity of R.equi is highly demanded.In conclusion,the epidemiological information of R.equi in the air and the soil from horse farms in China was discribed,and the drug sensitivity and the vap gene of the R.equi isolates were charactorized,for the first time.These provide the theoretical basis,foundimental data and resource bank of R.equi,supporting prevention,control and treatment of R.equi in China.It is also of great important for public health. |
PDF Full Text Request