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Intermedilysin release by Streptococcus intermedius: effects of various antibacterial drugs at sub-MIC levels

Mark B Taylor1, Janice H L Oh, K L Kang

  • 1Department of Microbiology, National University of Singapore, Blk MD4, 5 Science Drive 2, Singapore 117597, Singapore. micmbt@nus.edu.sg

FEMS Microbiology Letters
|February 3, 2005
PubMed

Insights

Certain antibiotics, like clindamycin, significantly reduce the release of intermedilysin, a toxin from Streptococcus intermedius, by inhibiting its biosynthesis. This finding offers potential new strategies for managing infections caused by this human pathogen.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Streptococcus intermedius is a human pathogen that produces intermedilysin, a cytolytic toxin.
  • Understanding factors that regulate intermedilysin release is crucial for developing strategies against S. intermedius infections.

Purpose of the Study:

  • To investigate the effect of sub-minimum inhibitory concentrations (sub-MICs) of various antibiotics on intermedilysin release by S. intermedius.
  • To explore the potential mechanisms behind antibiotic-mediated modulation of intermedilysin production.

Main Methods:

  • Exposure of S. intermedius cultures to sub-MIC levels (1/2 MIC) of different classes of antibiotics.
  • Quantification of intermedilysin release into the culture supernatant.
  • Analysis of toxin biosynthesis and gene expression (mRNA levels) following antibiotic treatment.

Main Results:

  • Protein-inhibiting and nucleic acid-inhibiting antibiotics significantly decreased intermedilysin release.
  • Clindamycin demonstrated the most potent inhibitory effect on intermedilysin release at sub-MIC levels.
  • Cell wall-inhibiting antibiotics showed minimal impact on intermedilysin release.
  • Clindamycin exposure selectively reduced intermedilysin biosynthesis and release without altering mRNA levels of the intermedilysin gene.

Conclusions:

  • Sub-MIC concentrations of specific antibiotics, particularly clindamycin, can effectively reduce intermedilysin release from S. intermedius.
  • The mechanism involves decreased toxin biosynthesis rather than transcriptional regulation of the intermedilysin gene.
  • These findings suggest a potential therapeutic approach for managing S. intermedius infections by modulating toxin production.

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