| Objective:In the last decade, an increasing incidence of nonfermentative gram negative bacillus emerged, especially Acinetobacter spp. (mostly Acinetobacter baumannii) and Pseudomonas aeruginosa. Acinetobacter spp. is an opportunistic pathogen, it is found in many health care environments, soil, and water, and is a very effective human colonizer in the hospital. A. baumannii currently becomes one of the most important clinical pathogens, such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. A. baumannii is increasing even causes global outbreaks, displaying ever-increasing rates of resistance. Therefore, it is essential. to enhance the monitoring of bacterial resistance and the molecular mechanism of multi-drug resistance.Select Multi-drug resistant (MDR) Acinetobacter in our hospital during August 2007 to May 2008 were selected and homology were characterized. Finally to illustrated the function of 16S rRNA Methylase encoded genes associated with aminoglycosides resistance.1. The resistance and homology of MDR A.baumannii(1) Total of 61 MDR A. baumannii were screened from the isolates during July,2007 to May,2008. by using K-B method. Three more different types of antibiotic resistance identified as MDR A. baumannii.(2) OXA-51-like gene was analyzed by PCR and sequencing to identifized A.baumannii. 16S rRNA-23 S rRNA gene was amplified in OXA-51-like negative strains to identifiction. The results showed that during this 61 isolates ,fifty-five A.baumannii, three 3 TU Acinetobacter ,one 13TU Acinetobacter ,one Acinetobacter calcoaceticus and one Acinetobacter haemolyticus.(3) MICs of 14 antiacterials to 61 isolates of MDR A.baumannii were determinated by agar dilution. The rate of resistance to cefoperazone-sulbactam, minocycline and imipenem were 32.3%,16.1%,45.2%,The rate of resistance to polymyxin E was 9.7%,the lowest among the tested agents. The rates of resistance to all aminoglycoside were more than 90%.(4) Pulse field gel electrophoresis (PFGE) was performed to analyze the homology of 61 isolated MDR A.baumannii. This isolates belonged to the popular 5 clones. Clone A,28 strains; Clone B, 9 strains; We found that MDR Acinetobacter had spread widely in our hospitals.2,Study on Acinetobacter integron structure and the relationship of resistanceSpecificity primers of integrase were designed to detect incidence of integrase gene and its type by PCR and DNA sequencing ;Analysis of resistance rate between integron-positive and integron-negative strain by statistical software.PCR were used to determin drug resistance gene cassette in variable region of integrons by primers and sequencing. The results of PCR and DNA sequencing were BLAST on GeneBank, All we need is to find out the situation of drug resistance gene cassette to anylise the structures of integrons.Class 1 integrons were detected in 82% of multi-resistant Acinetobacter,whereas no strains contained a class 2 or 3 integron . The resistance of aminoglycosides and quinolones were higher in integron-positive strain than in integron-negative strain . PCR amplification was performed in 50 integron-positive strain,Integrons with various inserted sizes were found in 27 multi-resistant A.baumanii. The range of inserted gene cassette sizes detected varied from 1000bp to 4000bp. Gene cassettes aacA4,catB8,aadA1 were found in 3 strains, Gene cassettes aacC1,orfX,orfX′,aadA1 were in 9 strains,4 strains had arr-3,aadA4 gene, dfrA12,orfF,aadA2 were existended in 1 strain. Integron of A .baumannii in our hospital were mediated aminoglycoside and chloramphenicol resistance.3,Study on mediate high-level aminoglycoside-resistant 16S rRNA methylase gene Mediate high-level aminoglycoside-resistant 16S rRNA methylase gene armA,rmtA, rmtB, rmtC, rmtD and npmA gene were amplified by PCR. Among 61 MDR Acinetobacter,armA gene was detected in 47 isolates. All isolates were negative for rmtA,rmtB,rmtC,rmtD,and npmA genes. It can explan Acinetobacter high-level aminoglycoside resistance in our hospital. |
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