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Is hydrogen peroxide responsible for the inhibitory activity of alpha-haemolytic streptococci sampled from the

Krister Tano1, Eva Grahn Håkansson, Pia Wallbrandt

  • 1Department of Clinical Sciences, Otorhinolaryngology, Umeå University, Umeå, Sweden. krister.tano@nll.se

Acta Oto-Laryngologica
|September 5, 2003
PubMed
Abstract

Insights

Alpha-haemolytic Streptococci (AHS) inhibit common ear infection pathogens. This inhibitory effect is caused by hydrogen peroxide produced by AHS, offering insights into mucosal defense mechanisms.

Area of Science:

  • Microbiology
  • Otolaryngology
  • Immunology

Background:

  • Alpha-haemolytic Streptococci (AHS) exhibit in vitro inhibitory effects against key otitis media pathogens.
  • Otitis media is commonly caused by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

Purpose of the Study:

  • To elucidate the mechanism behind the observed inhibitory activity of AHS.
  • To identify the specific agent responsible for AHS's antimicrobial properties.

Main Methods:

  • Size-exclusion chromatography was used to fractionate AHS filtrate and identify inhibitory components.
  • Catalase was employed to assess the role of hydrogen peroxide in the inhibitory effect.
  • Quantitative analysis measured hydrogen peroxide levels in AHS filtrate.
  • Electron microscopy examined bacterial morphological changes induced by AHS filtrate.

Main Results:

  • Inhibitory activity was localized to low molecular weight fractions of the AHS filtrate.
  • The addition of catalase completely abolished the inhibitory effect of the AHS filtrate.
  • High concentrations of hydrogen peroxide (approximately 3 mmol/l) were detected in potent inhibitory filtrates.
  • Electron microscopy revealed bacterial damage consistent with hydrogen peroxide exposure.

Conclusions:

  • The inhibitory action of AHS against otitis media pathogens is primarily attributed to hydrogen peroxide production.
  • The findings highlight the role of hydrogen peroxide produced by AHS in both non-specific and specific mucosal defense systems.

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