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).

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.

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.