| Because of the extensive use of antimicrobial agents in recent years, As an opportunistic pathogen, Enterococcus infection rates continue to rise, especially for those patients with severe underlying diseases and low immunity. The pathogen is easy to invade the body or translocation. The majority of local or sysTEMic infection caused by multiple drug-resistant strains of Enterococcus. Enterococci due to their cell wall thickness, showing a variety of inherent resistance to antimicrobial agents. Such as cephalosporins, low concentrations of aminoglycosides, clindamycin and compound sulfonamide even if the sensitivity in vitro, clinical effects are poor. US statistics show that Enterococcus is the second pathogen of hospital-acquired urinary tract infection and wound infection, the third place in hospital-acquired bacteremia. Serious or fatal infections that Multi-drug resistant Enterococci caused have become the great challenges facing clinicians. Human infection caused by Enterococcus mainly E. faecalis and E. faecium, accounting for about 95% of the total.Enterococcus drug-resistance mechanisms include the inherent resistance of chromosomal genes and extra-chromosomal genetic units such as plasmids, transposable phage, transposable elements and other DNA fragments carrying acquired resistance.Objective: To investate the distribution and drug resistance of Enterococcus strains clinic isolated, to examine the genetic mechanisms of resistance by molecular methods and to provide evidence for the clinical therapy of infections. Methods: Using the agar dilution test recommended by CLSI M7-A8 to test the MIC of 112 stains E. faecalis and 118 stains E. faecium to 13 antimicrobial agents; Applicating PCR amplification and gene sequencing analyse TEM, aac(6')/aph(2"), aph(3')-â…¢,ant (6) -I, tetM, ermB, mefA, vanA, vanB, and intI1 as well as pbp4 and pbp5 whether the gene mutation.Results: 230 strains of enterococci resistant to antimicrobial agents were penicillin (57.4%), ampicillin(54.8%), chloromycetin(31.7%), ciprofloxacin(64.8%), levofloxacin (60.0%), erythromycin(57.4%), tetracycline(48.7%), high concentrations of gentamicin (66.5%) and high concentration of streptomycin(52.2%), none of them resist to vancomycin, teicoplanin and linezolid. TEM gene positive rate of 14.6% and 2.1% in E. faecalis and E. faecium, pbp4 gene of E. faecalis No.369 amino acid mutation is present, E. faecium pbp5 gene were found of 11 sites of mutation causes amino acid change. aac (6')/aph (2") gene positive rates were 80.2% and 93.8%, aph (3')-III gene positive rates were 29.2% and 39.6%, ant(6)-I gene positive rate 31.3% and 43.8%, ermB gene positive rates were 83.3% and 77.1%, tetM gene positive rates were 72.9% and 45.8%, not detected mefA, vanA, vanB, and intI1 genes.Conclusion: Clinical isolates of Enterococcus in urinary tract infection the most common, E. faecium antimicrobial resistance rate higher than E. faecalis, and multi -drug resistance and high resistance quite serious. TEM genes led to the main mechanism of E. faecalis resistant to penicillin-type drugs, the mutations of pbp5 gene leading to resistance of E. faecium to penicillin-type drugs the main mechanism; Enterococcus HLAR mainly by the aac(6')/aph(2") gene-mediated; Enterococcus produce ermB gene is the main reason for drug resistance to macrolides; Enterococcus carrying tetM gene is the main reason for resistance to tetracycline. In the treatment should be based on characteristics of drug resistance and different species to select the appropriate treatment; using vancomycin, teicoplanin and linezolid treatment to treat enterococcal infections is still the best method currently.
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