Molecular characterization of CTX-M type Extended Spectrum Beta Lactamase producing E. coli isolated from humans and the environment

Indian J Med Microbiol. 2015 Feb:33 Suppl:73-9. doi: 10.4103/0255-0857.150896.


Purpose: Escherichia coli is a common pathogen causing community- and hospital-acquired infections. The infections caused by the Extended Spectrum Beta Lactamase (ESBL) enzymes-producing E. coli hinder antibiotic treatment.

Materials and methods: Plasmid DNA samples were subjected to PCR specific for TEM, SHV and CTX-M genes obtained from 110 E. coli strains isolated from hospitalized patients, healthy individuals and environment in Vellore, South India .

Results: Among the 110 isolates tested, 21.8% were positive for TEM and 2.7% positive for SHV and 91.8% positive for CTX-M. The proportion of CTX-M positive E. coli was not statistically different between the study groups. Nineteen of 20 strains were CTX-M-15 type and the other was CTX-M-14 type. The phylogenetic analysis of 19 strains clustered with the pandemic CTX-M-15-ST131 strain, indicating this as an evolving global problem for antibiotic therapy. The geomapping of samples indicated 'hotspot' areas of healthy individuals, patients and the environmental samples.

Conclusion: The spatial presentation of GIS mapping allowed identification of clustering among patients and healthy individuals and contaminated environmental points.

MeSH terms

  • Case-Control Studies
  • Computational Biology
  • Cross Infection
  • Environmental Microbiology*
  • Escherichia coli / classification
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology*
  • Genotyping Techniques
  • Humans
  • Incidence
  • India
  • Phylogeny
  • Plasmids
  • Polymerase Chain Reaction
  • beta-Lactamases / genetics*


  • beta-Lactamases