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Prevalence of pilus-encoding islets among acute otitis media Streptococcus pneumoniae isolates from Israel

M Moschioni1, G De Angelis, S Melchiorre

  • 1Novartis Vaccines and Diagnostics srl, Research Center, Siena, Italy.

Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
|November 6, 2009
PubMed

Insights

The distribution of Streptococcus pneumoniae pilus islets (PI-1 and PI-2) was studied in Israeli acute otitis media isolates. PI-1 was found in 30.1% and PI-2 in 7%, with PI-1 more frequent in antibiotic-resistant strains.

Area of Science:

  • Microbiology
  • Genetics
  • Infectious Diseases

Background:

  • Streptococcus pneumoniae is a leading cause of bacterial infections, including acute otitis media.
  • Pilus islets (PI-1 and PI-2) are genetic elements involved in S. pneumoniae virulence.
  • Understanding the distribution of these islets is crucial for tracking pathogen evolution and antibiotic resistance.

Purpose of the Study:

  • To determine the prevalence of PI-1 and PI-2 in clinical isolates of S. pneumoniae from Israel.
  • To investigate the correlation between pilus islet presence, multilocus sequence typing (MLST) genotypes, serotypes, and antibiotic resistance.

Main Methods:

  • Analysis of 113 clinical isolates of S. pneumoniae causing acute otitis media.
  • Detection of PI-1 and PI-2 using molecular methods.
  • Multilocus sequence typing (MLST) for genotypic characterization.
  • Serotyping to determine the capsular polysaccharide type.
  • Assessment of antibiotic resistance patterns.

Main Results:

  • PI-1 was detected in 30.1% (34/113) and PI-2 in 7% (8/113) of the isolates.
  • PI-2 was exclusively found in isolates that also harbored PI-1.
  • Pilus islet presence correlated with specific MLST genotypes (ST156 and ST236) but not with serotype.
  • A higher frequency of PI-1 was observed among antibiotic-resistant isolates.

Conclusions:

  • Pilus islets PI-1 and PI-2 show varying distribution in Israeli S. pneumoniae isolates causing AOM.
  • The presence of PI-1 is associated with antibiotic resistance, suggesting a role in pathogen adaptation.
  • Genotypic correlation, but not serotypic, was observed with pilus islet carriage.

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