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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
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Genetic diversity of Streptococcus pneumoniae in Tunisia

B Midouni1, E Mehiri2, A Ghariani2

  • 1Microbiology Laboratory, A. Mami Hospital of Pneumology, UR12/SP18, Ariana, Tunisia; Faculty of Sciences of Tunis, University of Tunis El Manar, Ariana, Tunisia.

International Journal of Antimicrobial Agents
|October 9, 2018
PubMed
Abstract

Insights

This study investigated Streptococcus pneumoniae in Tunisia, finding widespread erythromycin resistance and the international spread of resistant clones. Genetic analysis revealed significant diversity among serotypes, highlighting the need for ongoing surveillance of antimicrobial resistance.

Area of Science:

  • Microbiology
  • Genetics
  • Epidemiology

Background:

  • Streptococcus pneumoniae is a leading cause of bacterial infections globally.
  • Understanding the genetic diversity and antimicrobial resistance patterns of S. pneumoniae is crucial for effective treatment and prevention strategies.
  • Previous studies have highlighted the emergence of drug-resistant strains, necessitating continuous monitoring.

Purpose of the Study:

  • To explore the genetic diversity of Streptococcus pneumoniae isolates in a Tunisian pneumology hospital.
  • To determine antimicrobial susceptibility patterns and identify prevalent serotypes and sequence types (STs).
  • To investigate the presence of international antimicrobial-resistant clones.

Main Methods:

  • Analysis of 141 S. pneumoniae strains isolated between 2009-2016.
  • Antimicrobial susceptibility testing using disk diffusion and Etest for MIC determination.
  • Serotyping via multiplex PCR and sequence typing (STs) using multilocus sequence typing (MLST).

Main Results:

  • High rates of resistance to erythromycin (69.5%) and non-susceptibility to penicillin (63.8%) were observed.
  • Twenty-five serotypes were identified, with vaccine coverage varying for PCV7, PCV10, and PCV13.
  • Seventy-three STs were identified, including 23 novel STs, with ST179, ST3772, ST2918, and ST4003 being most frequent.
  • Three international antimicrobial-resistant clones (Denmark14-ST230, Spain9V-ST156, Portugal19F-ST177) were identified.

Conclusions:

  • The study highlights the clonal and international dissemination of antimicrobial-resistant S. pneumoniae.
  • Significant genetic variation exists within different serotypes, as revealed by MLST.
  • Findings underscore the importance of continuous surveillance for antimicrobial resistance and genetic diversity of S. pneumoniae in Tunisia.
Keywords:
MLSTResistanceSerotypeStreptococcus pneumoniae

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