Emergence of oxacillinase-mediated resistance to imipenem in Klebsiella pneumoniae

Antimicrob Agents Chemother. 2004 Jan;48(1):15-22. doi: 10.1128/AAC.48.1.15-22.2004.


Klebsiella pneumoniae strain 11978 was isolated in Turkey in 2001 and was found to be resistant to all beta-lactams, including carbapenems. Cloning and expression in Escherichia coli identified five beta-lactamases, including two novel oxacillinases. The beta-lactamase OXA-48 hydrolyzed imipenem at a high level and was remotely related (less than 46% amino acid identity) to the other oxacillinases. It hydrolyzed penicillins and imipenem but not expanded-spectrum cephalosporins. The bla(OXA-48) gene was plasmid encoded and not associated with an integron, in contrast to most of the oxacillinase genes. An insertion sequence, IS1999, was found immediately upstream of bla(OXA-48). Another plasmid that encoded a second oxacillinase gene, bla(OXA-47), located inside a class 1 integron was identified in K. pneumoniae 11978. OXA-47 had a narrow spectrum of hydrolysis activity and did not hydrolyze ceftazidime or imipenem, as is found for the beta-lactamase (OXA-1) to which it is related. In addition, beta-lactamases TEM-1 and SHV-2a were expressed from the same K. pneumoniae isolate. Analysis of the outer membrane proteins of this isolate revealed that it lacked a porin of ca. 36 kDa. Thus, the high-level resistance to beta-lactams of this clinical isolate resulted from peculiar beta-lactamases and modification of outer membrane proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Proteins / chemistry
  • Carrier Proteins / isolation & purification
  • Carrier Proteins / metabolism*
  • Cloning, Molecular
  • DNA Primers
  • DNA, Bacterial / chemistry
  • Drug Resistance, Bacterial
  • Hydrolysis
  • Imipenem / metabolism
  • Imipenem / pharmacology*
  • Isoelectric Focusing
  • Kinetics
  • Klebsiella pneumoniae / drug effects*
  • Klebsiella pneumoniae / enzymology*
  • Klebsiella pneumoniae / genetics
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Plasmids / genetics
  • Thienamycins / metabolism
  • Thienamycins / pharmacology*
  • beta-Lactam Resistance
  • beta-Lactamases / isolation & purification
  • beta-Lactamases / metabolism*


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Carrier Proteins
  • DNA Primers
  • DNA, Bacterial
  • Thienamycins
  • Imipenem
  • beta-Lactamases
  • oxacillinase