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Diverse virulent pneumophages infect Streptococcus mitis

Siham Ouennane1, Philippe Leprohon2, Sylvain Moineau1

  • 1Département de Biochimie, Microbiologie et Bio-Informatique, Faculté des Sciences et de Génie, Groupe de Recherche en Écologie Buccale, Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Québec City, Québec, Canada.

Plos One
|February 19, 2015
PubMed

Insights

Two virulent phages, Cp-1 and Dp-1, previously isolated from Streptococcus pneumoniae, were found to infect and replicate in Streptococcus mitis. This discovery offers potential phage therapy alternatives for bacterial endocarditis caused by these related species.

Area of Science:

  • Microbiology
  • Virology
  • Genetics

Background:

  • Streptococcus mitis is a leading cause of bacterial endocarditis.
  • Increasing antibiotic resistance in S. mitis and Streptococcus pneumoniae necessitates alternative treatments.
  • Bacteriophages are being re-evaluated as potential antimicrobial agents.

Purpose of the Study:

  • To investigate the infectivity of pneumophages Cp-1 and Dp-1 on S. mitis.
  • To compare phage replication and genomic stability in S. mitis versus S. pneumoniae.
  • To re-evaluate and potentially reclassify phage Cp-1 based on genomic analysis.

Main Methods:

  • Microbiological assays to assess phage replication and plaque formation.
  • Phage adsorption and burst size experiments.
  • Whole-genome sequencing of phages grown on different hosts.

Main Results:

  • Virulent phages Cp-1 (Podoviridae) and Dp-1 (Siphoviridae) successfully infected and replicated in S. mitis.
  • Phages produced visible plaques on S. mitis, though with lower burst size and adsorption rates compared to S. pneumoniae.
  • Genomic sequencing confirmed identical nucleotide sequences, indicating the same phages infect both species.
  • The genome of Cp-1 differed from previous reports, leading to its renaming as SOCP.

Conclusions:

  • Pneumophages Cp-1 and Dp-1 demonstrate infectivity against S. mitis, expanding their potential therapeutic applications.
  • Phage genomes remain stable when replicating in S. mitis, supporting their use in phage therapy.
  • The reclassification of Cp-1 to SOCP refines phage taxonomy and understanding.

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