| Objective To study the existence of theβ-lactamase gene produced by multidrug-resistant Psedomonas aeruginosa isolated from respiratory tract.Methods Antimicrobial susceptibility was tested by Kirby-Bauer method. A modified three-dimensional test was used to detect theβ-lactamase phenotypes of 46 multidrug-resistant Psedomonas aeruginosa strains.β-lactamases genotypes were analyzed by PCR amplification and product sequencing.Resultsβ-lactamases were detected in 29 of the 46 isolates: 21 isolated produced AmpCβ-lactamase,two of them harboring CARB-3 gene. 2 isolated produced extended-spectrumβ-lactamase (ESBL) and harboring TEM gene.6 isolated produced otherβ-lactamases,in 4 fo 6 harboring CARB-3 gene and three of them harboring IMP gene.The genotypes of 2 isolated produced otherβ-lactamases were not find out. SHV,PER,VEB,OXA-10,GES,CTX-M,MIR,,VIM genes and plasmid-mediated DHA gene were negative.The oprD2 gene was lack in 34 isolates.Conclusions Chromosomal-mediated AmpCβ-lactamase is the major (21/46) and CARB-3 is the next place (6/46) of theβ-lactamase produced by multidrug-resistant aeruginosa in our hospital. The isolated produced ESBLs are less (2/46), harboring TEM gene. IMP metallo-β-lactamase gene is discovered (3/46) and it is harbored with CARB-3 gene in the same strains. It is widespread that multidrug-resistant aeruginosa strains lack oprD2 gene (34/46).
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