Identification of CTX-M beta-lactamases in Escherichia coli from hospitalized patients and residents of long-term care facilities

Diagn Microbiol Infect Dis. 2010 Apr;66(4):402-6. doi: 10.1016/j.diagmicrobio.2009.11.012.


Bacteria harboring CTX-M extended-spectrum beta-lactamases (ESBLs) have been identified worldwide, with most reports coming from regions outside North America. We have identified CTX-M enzymes in 31% of ESBL-positive Escherichia coli isolates from our hospital and more than half (53%) of the isolates from associated long-term care facilities. Approximately 3/4 of all CTX-M-bearing isolates were from urine specimens, with a predominance of CTX-M-15. A large proportion of such isolates were nonsusceptible to levofloxacin, trimethoprim/sulfamethoxazole, and all beta-lactam antimicrobials with the exception of the carbapenems, requiring carbapenem therapy for acute urinary tract infection or urinary tract-related sepsis. CTX-M beta-lactamases have emerged within our location, and detection of bacteria harboring these enzymes in the clinical microbiology laboratory remains problematic because molecular methods are needed for their identification.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Typing Techniques
  • Cluster Analysis
  • Cross Infection / microbiology*
  • DNA Fingerprinting
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli / classification
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / microbiology*
  • Escherichia coli Proteins / biosynthesis*
  • Escherichia coli Proteins / genetics
  • Female
  • Genotype
  • Hospitals
  • Humans
  • Long-Term Care
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • United States
  • beta-Lactam Resistance
  • beta-Lactamases / biosynthesis*
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Escherichia coli Proteins
  • beta-Lactamases