Investigation of β-lactamases and β-lactamase-related resistant genes in multidrug-resistant Pseudomonas aeruginosa

OBJECTIVE To investigate β-lactamase and resistant genes in multidrug-resistant Pseudomonas aeruginosa isolated from clinical specimens.METHODS The antibiotic susceptibility of 17 different antibiotics of P.aeruginosa was tested by K-B method,and 135 multidrug-resistant strains were screened.The three-dimensional method was taken to differentiate the various β-lactamases.Resistant genes of β-lactamases and oprD2 genes were detected by polymerase chain reaction(PCR).RESULTS Among the 135 strains of multidrug-resistant P.aeruginosa,the detection rate of AmpC beta-lactamases was highest(36.3%),the second was ESBLs plus AmpC β-lactamases(14.8%),the third was metallo-beta-lactamases(MBL)(13.3%),ESBLs plus AmpC variants accounted for 11.9%,AmpC variants accounted for 5.2%,ESBLs accounted for 4.4%;the detection rates of β-lactamase gene CTX-M-1 group,TEM,CARB,DHA and IMP were 45.9%,25.9%,12.6%,10.4%,and 3.7%,respectively,and none of the 135 strains possessing the genes of SHV,OXA-10 group,PER,GES,VEB,and VIM were detected;the loss rate of oprD2 gene was 69.6%.CONCLUSION The main β-lactamases are AmpC beta-lactamases,the resistance toβ-lactamases antibiotics is related to the resistant genes of CTX-M-1 group,TEM,CARB,DHA and IMP,and the resistance to carbapenem is related to the loss of oprD2 gene.