Abstract： Background In the present study,we characterized multidrug-resistant Pseudomonas aeruginosa (MDRP) clinical isolates from a paediatric facility and investigated the types and features of the metallo-β-lactamases (MBLs) produced by carbapenem-resistant strains.Methods Four hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children's Hospital between January 2005 and December 2006.The minimal inhibition concentrations (MICs) of the strains for 13 antibiotics were measured.A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains.Results We found that 24.1% (120/498) of the isolates were MDRP.The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%,respectively,and the MIC50 and MIC50 values for the two antibiotics were identical at 4 μg/ml and 32 μg/ml,respectively.The detection rate for carbapenem resistance was 49.2% (59/120).Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains,39 (66.1%) were positive for the MBL genotype;35 (89.7%)strains carded the blaIMP gene and 4 (10.3%) strains carried the blaVIM gene.Neither blaSPM nor blaa~M was amplified from any of the 59 isolates.DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates.Conclusions These MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing,China.The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.