The β-lactamase gene content and epidemiology of ceftazidime-resistant Pseudomonas aeruginosa isolates (24% of the total number of P. aeruginosa isolates) were investigated at a University Hospital in Thailand during a 4-month period in 1999. Of 33 nonrepetitive clinical isolates, 31 produced a VEB-1—like clavulanic acid—inhibited extended-spectrum β-lactamase (ESBL). These isolates belonged to different pulsed-field gel electrophoresis types and subtypes. In 1 case, the bla_VEB-1-like gene was plasmid located. The bla_VEB-1-like genes were present as a gene cassette on class 1 integrons that...

The β-lactamase gene content and epidemiology of ceftazidime-resistant Pseudomonas aeruginosa isolates (24% of the total number of P. aeruginosa isolates) were investigated at a University Hospital in Thailand during a 4-month period in 1999. Of 33 nonrepetitive clinical isolates, 31 produced a VEB-1—like clavulanic acid—inhibited extended-spectrum β-lactamase (ESBL). These isolates belonged to different pulsed-field gel electrophoresis types and subtypes. In 1 case, the bla_VEB-1-like gene was plasmid located. The bla_VEB-1-like genes were present as a gene cassette on class 1 integrons that varied in size and structure. In most cases, the veb-1 cassette was associated with an arr-2 cassette (rifampin resistance), aminoglycoside resistance gene cassettes, and an oxa-10—like cassette encoding a narrow-spectrum oxacillinase-type β-lactamase. The present study indicates that ESBLs may be endemic in P. aeruginosa and illustrates that integrons are efficient means for their spread.