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Assessing Respiratory Immune Responses to Haemophilus Influenzae
06:32

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Published on: June 29, 2021

Novel bla(TEM)-positive ampicillin-susceptible strains of Haemophilus influenzae

Stephen G Tristram1

  • 1School of Human Life Sciences, University of Tasmania, Newnham Drive, Launceston, Tasmania 7250, Australia. Stephen.Tristram@utas.edu.au

Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
|October 27, 2009
PubMed

Insights

Two ampicillin-susceptible Haemophilus influenzae strains carrying blaTEM genes showed resistance due to a weak promoter mutation and an inactive TEM enzyme. This highlights novel mechanisms of ampicillin resistance in bacteria.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Haemophilus influenzae is a significant human pathogen.
  • Antibiotic resistance, particularly to ampicillin, is a growing public health concern.
  • The blaTEM gene is a common source of beta-lactamase-mediated resistance.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying ampicillin susceptibility in Haemophilus influenzae strains carrying blaTEM genes.
  • To identify genetic alterations responsible for the expression or function of TEM enzymes.

Main Methods:

  • Genomic DNA extraction and sequencing.
  • Promoter region analysis.
  • Enzyme activity assays.
  • Bacterial strain characterization.

Main Results:

  • Two ampicillin-susceptible Haemophilus influenzae strains were identified with blaTEM genes.
  • One strain exhibited ampicillin susceptibility due to poor expression of a functional TEM-1 enzyme, linked to a promoter mutation.
  • The second strain showed susceptibility because of the production of an inactive mutant TEM enzyme.

Conclusions:

  • Ampicillin susceptibility in H. influenzae with blaTEM genes can arise from mechanisms other than complete gene absence.
  • Mutations affecting promoter activity or enzyme integrity are key factors in bacterial antibiotic resistance.
  • Understanding these resistance mechanisms is crucial for effective antimicrobial stewardship.

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