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Clonal relationships among high-level penicillin-resistant Streptococcus pneumoniae in the United States

G V Doern1, A B Brueggemann, M Blocker

  • 1University of Massachusetts Medical Center, Worcester, USA.

Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America
|November 3, 1998
PubMed

Insights

Antimicrobial resistance in Streptococcus pneumoniae is a growing concern. Most penicillin-resistant S. pneumoniae strains in the U.S. currently belong to a limited number of clonal groups, indicating potential shared origins.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Epidemiology

Background:

  • Antimicrobial resistance in Streptococcus pneumoniae has significantly increased in the U.S. over the past 6-7 years.
  • Penicillin resistance is a notable issue, with 26.5% of isolates showing intermediate resistance and 17.5% high-level resistance.

Purpose of the Study:

  • To investigate clonal relationships among current isolates of high-level penicillin-resistant Streptococcus pneumoniae (PRSP) in the United States.
  • To understand the genetic relatedness of PRSP strains circulating in the U.S.

Main Methods:

  • Characterization of 147 PRSP isolates from a 1994-1995 U.S. surveillance study.
  • Analysis included serotyping, antimicrobial susceptibility profiling, and pulsed-field gel electrophoresis (PFGE).

Main Results:

  • Only six serotypes (6A, 6B, 9A, 14, 19F, 23F) were identified among the PRSP isolates.
  • A significant proportion of isolates (70.1%) shared nine PFGE types, with 51.7% belonging to just four PFGE profiles.

Conclusions:

  • The majority of high-level penicillin-resistant Streptococcus pneumoniae strains in the U.S. are derived from a limited number of clonal groups.
  • This suggests that specific clones are responsible for the spread of PRSP in the United States.

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