Prevalence of the genes encoding extended-spectrum β-lactamases, in Escherichia coli resistant to β-lactam and non-β-lactam antibiotics

G. M. Matar, Souhaila M. Al Khodor, M. El-Zaatari, M. Uwaydah

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The prevalences of extended-spectrum β-lactamases (ESBL) and their encoding bla genes, TEM, SHV and CTX_M, were investigated in isolates of Escherichia coli that were resistant to β-lactam and/or non-β-lactam antibiotics. Of the 250 E. coli isolates investigated, all of which came from patients in a major hospital in southern Lebanon, 61 (13.3%) were found to have ESBL, their production of β-lactamase being confirmed by the ceftazidime and ceftazidime/clavulanic-acid disc methods. All 61 ESBL isolates were resistant to β-lactams and sensitive to imipenem, piperacillin/tazobactam and cefoxitime. Only 40% were resistant to fluoroquinolones, 33% were resistant to aminoglycosides, and 18% were considered to have multi-drug resistance. The results of the PCR-based amplification of the bla gene in DNA samples from the 61 ESBL isolates indicated that 11 (18%) of the isolates carried both the TEM and SHV genes, 37 (61%) carried the TEM gene but not the SHV, and 13 (21%) had the SHV gene but not the TEM. None of the isolates carried the CTX_M gene. Of the 37 TEM-positive/SHV-negative isolates, 43% were resistant to fluoroquinolones and 37% to aminoglycosides. Increased resistance to non-β-lactam antibiotics was observed in the isolates harbouring both the TEM and SHV genes, of which 54% were resistant to all of the tested antibiotics except imipenem, 36% were only resistant to fluoroquinolones, and 9.1% only resistant to aminoglycosides. The possibility that the concomitant presence of TEM- and SHV-type β-lactamases is associated with resistance to non-β-lactam antibiotics requires further research. The prevalences of ESBL and their encoding genes in Gram-negative bacteria collected from various regions in Lebanon will now be investigated.

Original languageEnglish
Pages (from-to)413-417
Number of pages5
JournalAnnals of Tropical Medicine and Parasitology
Issue number4
Publication statusPublished - Jun 2005
Externally publishedYes


ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases
  • Immunology

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