| Enterococcus faecalis is one of the normal flora of human and animal intestines, it is an important pathogen and often used as an indicator.In particular, antibiotics widely used in animal husbandry,it was very difficult to treat. Meanwhile, the study on the mechanism of bacterial drug resistance and integrons carrying resistance gene cassettes is mediated by the multi-drug-resistant Enterococcus faecalis or not, has become a key issue to be resolved.For that reason,this study using animal source of Enterococcus faecalis as object,using general microbiology and molecular biology methods to identify the isolate strains,select multi resistant bacteria,detect class I integron, find out resistance gene cassettes in variable region. Preliminary analysis of multiple drug resistance mechanism of Enterococcus faecalis,to provide theoretical basis for controlling the spread of drug resistance.1.Isolation and identification of the animal source of Enterococcus faecalisUsing conventional microbiological methods,isolation and purification of the suspected isolates from feces and anal swab from 194 animal sources, 285 strains of the isolates were isolated and identified, there were 49 strains of pigs, 20 strains of cows, 174 strains of sheep,17 strains of horses, 21 strains of pigs, 4 strains of dung beetles.2.Detection of drug resistant phenotype of animal derived from Enterococcus faecalisDisk diffusion method following the CLSI standards was used to select 8 kinds of clinical commonly antibiotics, detection and analysis of the drug resistance phenotype and multiple drug resistance of 285 strains of fecal.The results of the study showed that 285 strains of Enterococcus faecalis isolates had higer resistance to the penicillin92.28%,followed by streptomycin 82.11%, amoxicillin 64.91%, erythromycin 54.04%,tetracycline 45.26%, ciprofloxacin 40.00%, highly sensitive to ampicillin and furantoin.Among them 265 isolates presented a multiple drug resistance, 5 resistant to the most, up to 31.39%(91/285), then 6 resistant26.67%(76/285) and 4 resistant15.09%(43/285). 7 resistance strains were 20, the proportion reached 7.02%.PCR technique was used to detect the carrying status of 9 kinds of resistant genes of 285 strains of Enterococcus faecalis. The β-lactam resistance gene to tem detection rate up was77.89%, followed by tetM gene 33.68%, gyrA 37.54% and ParC 34.74%. The detection rate of aph(3’)-III 22.46% was the highest, followed by aac(6’)/aph2’’10.88% and ant(6’)-I8.42%, mef A genes were not detected.3.Class I integron and Multidrug Resistance of Enterococcus faecalisPCR detection method and binding sequence analysis was used to detect the class I integron gene and drug resistance gene cassette in the isolated strain. The result show that,the positive rate of class I integron intI gene was 36.60%. qacE△1-sul 1gene detection rate was 71.13%, The variable regions of 31 drug resistant genes were amplified,the detection rate was 31.96%, 31 strains carrying aadA2 encoding amino glycosides resistance gene box.The resistance phenotype and genotype of aminoglycosides(aph(3’)-III, aac(6’)/aph2’’,ant(6’)-I) were highly correlated.Other antibiotic resistance mechanisms associated with the gene cassette have not been found.The results show that the multiple drug resistance of Enterococcus faecalis in the surrounding area of Shihezi is more serious, there is a close relationship between class I integron. The research show that we should strengthen the monitoring of bacterial drug resistance, to avoid the class I integron of drug resistance genes transfer between animals and people by animal products. |
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