Incidence Rate Of Overexpressing AmpC β-lactamases In Cefoxitin-resistant Gram-negative Bacillus And Study On Drug-resistance And Drug-resistance Relative Gene

Gram-negative bacillus were common pathogenic bacteria or opportunistic pathogen and also the important pathogenic bacteria of nosocomial infection, the drug-resistance variation and multi-drug resistance occurance of which extremely complicated the clinic therapy.The chief mechanisms of Gram-negative bacillus resist to lactam antibiotics were the production of AmpC enzymes and ESBLs hydrolysising them.Since 1990's, AmpC enzymes have been found that they can been mediated by plasmids and can horizotal spread between different strains,new genotypes increasing by 1 to 2 every year. Different areas have different inactivators and different genotypes in response to the discrepan- cy of the kinds and the dosage of antibiotics usage.Consequentially, different inactiva- tors and different genotypes have different resistance phenotype and prevalence cha- racteristic. Accordingly, it would help control the dissemination of resistance genes and provide guide for antibiotics usage to investigate the prevalence status of resistan- ce genes in different areas.In the present study, a total of 156 clinical isolates of cefoxitin-resistant nonrepe- titive gram-negative bacillus collected by Fuzhou General Hospital, Fujian Provincial Hospital, the 476th Hospital of PLA and the Second Hospital of Fuzhou were detected by three-dimensional extract test for AmpCβ-lactamases and by ATB STREP and KB method for drug susceptibility. The position and the status of the horizontal metastasis of drug-resistance genes were detected by plasmids transformation experiments and conjugation experiments. Universal primer PCR for AmpC, ESBLs, BSBLand qnr gene amplification and DNA sequencing were carried out for genotype of drug-resis- tance genes. ERIC-PCR was used to reveal the genetic relationship between strains. Based on the results, we can get the message of the incidence rate of overexpressing AmpCβ-lactamases in cefoxitin-resistant gram-negative bacillus, the status of drug-resistance and the distributin of relative resistance gene in overexpressing AmpCβ-lactamases bacillus in Fuzhou.