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Evaluation of Fourier-Transform Infrared Spectroscopy with IR Biotyper® system for Streptococcus pneumoniae

Camila Tondolo Romero1,2, Natália Kehl Moreira3,4, Gabriela Rosa da Cunha3,4

  • 1Laboratório de Pesquisa Em Bacteriologia Clínica, LaBaC, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, Brazil. camila.tondolo@gmail.com.

European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology
|May 21, 2025
PubMed
Abstract

Insights

A new customized classifier for the IR Biotyper® system accurately serotypes Streptococcus pneumoniae, offering a faster alternative to traditional methods. This method shows improved performance for key serotypes and discriminating between closely related strains.

Area of Science:

  • Microbiology and Infectious Diseases
  • Analytical Chemistry
  • Bioinformatics and Computational Biology

Background:

  • Streptococcus pneumoniae is a major human pathogen, with its capsule being crucial for virulence.
  • Accurate serotyping of S. pneumoniae is vital for clinical and epidemiological surveillance.
  • Current gold-standard serotyping (Quellung reaction) is time-consuming and resource-intensive.

Purpose of the Study:

  • To evaluate the IR Biotyper® system, utilizing Fourier Transform Infrared Spectroscopy (FT-IRS), as a tool for S. pneumoniae serotyping.
  • To develop and assess a customized classifier, specifically targeting Pneumococcal Conjugate Vaccine (PCV15) serotypes.

Main Methods:

  • Initial evaluation of the commercial Pneumococci serogrouper (Bruker) with 188 retrospective S. pneumoniae isolates.
  • Development and validation of a PCV15-specific classifier using artificial neural network (ANN) machine learning on 1246 spectra.
  • Prospective evaluation of both classifiers using 61 S. pneumoniae isolates from South Brazil.

Main Results:

  • The customized PCV15-Classifier demonstrated higher agreement (86.7% retrospective, 75.4% prospective) compared to the commercial serogrouper (68.1% retrospective, 70.5% prospective).
  • The PCV15-Classifier showed superior performance for epidemiologically significant serotypes, including serotype 3.
  • The classifier effectively discriminated between closely related serotypes within serogroup 19 (19F and 19A).

Conclusions:

  • The IR Biotyper® system, enhanced with a customized classifier, is a valuable tool for S. pneumoniae serotyping.
  • This FT-IRS-based approach offers a more timely and potentially cost-effective alternative to traditional methods.
  • The classifier's ability to be retrained allows adaptation to evolving serotype prevalence.
Keywords:
Streptococcus pneumoniaeFT-IRSPCV15Serotyping

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