Objective To investigate the prevalence of plasmid-mediated fosfomycin resistance genes in Gram-negative bacilli and analyze the correlation with drug resistance .Methods A total of 133 Gram-negative bacilli were collected, including Escherichia coli (52 isolates, 39.1%), Pseudomonas aeruginosa (36 isolates, 27.1%), Klebsiella pneumoniae (31 isolates, 23.3%) and Acinetobacter baumannii (14 isolates, 10.5%).The antimicrobial susceptibility test was performed by Kirby-Bauer (K-B) method, and the plasmid-mediated fosfomycin resistance genes (fosA, fosA3 and fosC2) were detected by polymerase chain reaction ( PCR) .Results The fosfomycin-resistant rate of Escherichia coli was 9.6%(5/52), and the ones of Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii were 36.1%(13/36), 74.2%(23/31) and 64.3%(9/14), respectively.Five of 133 isolates were positive for fosA, and 5 isolates were positive for fosA3, all belonging to Escherichia coli or Klebsiella pneumoniae, while there was no fosC2 gene.Seven of 10 isolates with plasmid-mediated fosfomycin resistance genes were resistant to fosfomycin , and the other 3 isolates were sensitive. Conclusions The fosfomycin-resistant rates of Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii are higher than that of Escherichia coli.The fosA and fosA3 genes are detected in Escherichia coli and Klebsiella pneumoniae, whereas no fos gene is detected in Pseudomonas aeruginosa and Acinetobacter baumannii, highlighting the necessity of a comprehensive research in regard to fosfomycin resistance genes .%目的：了解质粒介导的磷霉素耐药基因在革兰阴性杆菌中的流行情况，并分析其与耐药性的关系。方法收集临床分离的133株革兰阴性杆菌，其中大肠埃希菌52株（39．1％）、铜绿假单胞菌36株（27．1％）、肺炎克雷伯菌31株（23．3％）、鲍曼不动杆菌14株（10．5％）。采用K－B纸片法进行药敏试验，通过聚合酶链反应（PCR）检测质粒介导的磷霉素耐药基因fosA、fosA3、fosC2，分析其与耐药性的关系。结果大肠埃希菌对磷霉素的耐药率为9．6％（5／52），铜绿假单胞菌、肺炎克雷伯菌和鲍曼不动杆菌的耐药率分别为36．1％（13／36）、74．2％（23／31）和64．3％（9／14）。磷霉素耐药基因fosA、fosA3阳性各5株，均为大肠埃希菌或肺炎克雷伯菌，未检出fosC2基因。10株质粒介导磷霉素耐药基因阳性菌株中，7株对磷霉素表现出耐药，其余3株表现为敏感。结论铜绿假单胞菌、肺炎克雷伯菌、鲍曼不动杆菌对磷霉素的耐药率均远高于大肠埃希菌。大肠埃希菌和肺炎克雷伯菌发现有fosA和fosA3基因，铜绿假单胞菌和鲍曼不动杆菌未见，尚不能解释表型试验结果，因此有必要进行更全面的耐药基因研究。
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