| Objective: To analyze the susceptibility of Enterecoccus to six antimicrobic agentsused commonly in clinic. To amplify the E. faecalis esp gene by polymerase chain reaction(PCR), and to construct cloning vector pUC18/esp, then the nucleotide sequences were analyzed. To explore the relativity between esp gene and resistance of derived-infection Enterecoccus faecalis. To understand the resistant situation of Enterecoccus and the relative factor of resistance in Enterecoccus faecalis, and offer the reference for preventing and treating the infection diseases led to Enterecoccus.Methods: 78 strains of the derived-infection Enterecocci were isolated, cultured anddetected. The Minimum inhibitory concentration (MIC) of six antimicrobic agents against 78 strains of Enterecocci was determined by agar dilution method. The clinical isolates showing different degree resistance to 6 antimicrobic agents and the multiply drug resistance were selected. PCR was used to amplify the esp gene, and PCR products were purified and cloned into the vector pUC18. The recombinant pUC18/esp was transformed into E.coli JM109. The positive clone was identified by blue-white, PCR, restriction endonuclease digestion and sequencing, and analyze the sequence with Blast software. The correlation of esp gene and resistance was studied.Results: In the 78 samples, Enterecoccus faecalis have 61 strain, accounting for78.2%; Enterecoccus faecalis have 15 strains, accounting for 19.2%,the others have 2 strains, accounting for 2.6%.The MIC50 and MIC90 of vancomycin to Enterecoccus were 0.5/μg/mL and 4/μg/mL. That of ampicillin and ciprofloxacin to Enterecoccus were 1μg/mL, 16μg/mL and 4μg/mL, 64μg/mL. That of azithromycin and erythromycin to Enterecoccus were 16μg/mL, 32μg/mL and 64μg/mL, 128μg/mL. Enterecoccus resistant to vancomycin had not been tested, and the resistant rates of Enterecoccus against ampicillin, ciprofloxacin, high-level gentamicin(MIC≥ 500 μg/mL), azithromycin and erythromycin were as follows: 16.7%, 53.8%, 56.4%, 74.4%, 85.9%, respectively.The resistant rates of E.faecium and E. faecalis against ampicillin were 9.8% and 46.7%(P<0.01), and the resistant rates of E.faecium and E. faecalis against ciprofloxacin were 50.8% and 73.3% (P<0.05)26 esp~+ strain had been detected by using PCR method from 61E. faecali strain. The positive rate of esp gene in the resistant strains against ampicillin, ciprofloxacin, high-level gentamicin, erythromycin was 33.3%, 54.8%, 70.6%, 51.0%, respectively, and the positive rate of esp gene in the susceptible strains was 43.6%, 30.0%, 7.4%, 8.3%, respectively, esp gene was significantly more common among ciprofloxacin, high-level gentamicin, erythromycin than ampicillin resistant strains(P<0.05). The resistance of esp~+ strains was 7.7%, 65.4%, 92.3%, 96.2% and The resistance of esp" strains was 11.4%, 40.0%, 28.6%, 68.6%, respectively. The resistance of esp~+ strains against ampicillin, ciprofloxacin, high-level gentamicin, erythromycin was higher than than of esp~- strains(P<0.05). In the esp~+ strains, the resistant strains against two and three antimicrobic agents accounted 46.2%, and the resistant strains against four antimicrobic agents accounted 7.6%. In the esp" strains, the resistant strains against two antimicrobic agents accounted 34.3%, the resistant strains against three antimicrobic agents accounted 2.9%, and the resistant strains against four antimicrobic agents accounted 5.7%.Conclusion:1. The susceptibility of vancomycin was the best in the 6 commonly used antimicrobic agents and the degree of resistance of Enterecoccus varied in other... |
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