Aminoglycosides Resistant Gene Arma Real-time PCR Detection And Application Of And The Characteristic Study Of NDM-5 Producing Escherichia Coli

16S rRNA methylase armA, an important mechanism mediated high-level resistance to aminoglycosides were more and more popular in gram-negative bacteria. Establishment of the rapid detection method would be helpful to realize the distribution feature and transmission mechanism of armA. Primers and probe were designed and real-time PCR method to detect armA gene was built. The sensitivity and specificity of the method was evaluated by using standard concentration positive plasmids, feces simulation specimens and common pathogens not carrying armA gene respectively. Results showed that the method had prefect specifity and high sensitivity. The sensitivity reached to 4.10×101copy/ml of plasmid DNA sample and 1.5 x 104 cfu/mL of feces simμlation specimens.A total of 846 clinical gram-negative bacteria and 107 zoonotic Klebsiella strains were collected. ArmA was detected by the real-time PCR method. The result revealed that the rate of armA-positive strains reached to 22.0% of clinical strains. Acinetobacter strains had the highest rate of armA-positive in clinical isolates, which reached to 66.5%. The rate of armA-positive in zoonotic Klebsiella strains reached to 65.4% which was more higher than that in clinical Klebsiella strains. The minimal inhibitory concentration of amikacin and gentamicin were measured by Vitek 2 Compact system. The resistance rates of amikacin and gentamicin in clinical strains were 31.3% and 60.4%, respectively. The highest resistance rates of amikacin and gentamicin were also observed in Acinetobacter, which attached to 86.4% and 90.9% respectively. The resistance rates of amikacin and gentamicin were 74.8% and 79.4% in zoonotic Klebsiella strains. Among armA-positive strains, there were 94.6% strains resistant to amikacin, and 97.8% strains resistant to gentamicin. Therefore, carrying armA gene had high consistency with aminoglycosides resistance.Furthermore, Four NDM-5 procducing Escherichia coli isolates were also characterized in this study. The four NDM-5 positive E. coli strains deemed to responsible for infections were isolated from four independent patients in different cities in China. Isolates confered resistance to all β-lactams with the exception of aztreonam. Two strains belonged to sequence type (ST)167, while the other strains belonged to ST2608 and ST2294 respectively. They all shared an identical NDM-5 carrying IncX3 plasmid. NDM-5 dissemination mediated by the clonal spread of NDM-5 producing ST167 and inter-ST transfer of the IncX3 plasmid might be common in China. More effords should be taken to survey the NDM-1 dissemination.