Dataset Information

Differentiation of Streptococcus pneumoniae from nonpneumococcal streptococci of the Streptococcus mitis group by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

ABSTRACT: The differentiation of species within the Streptococcus mitis group has posed a problem in the routine diagnostic microbiology laboratory for some time. It also constitutes a major weakness of recently introduced matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) fingerprinting systems. As the phylogenetic resolution of the spectral similarity measures employed by these systems is insufficient to reliably distinguish between the most closely related members of the group, the major pathogen Streptococcus pneumoniae is frequently misidentified. In this study, a comparative analysis of MALDI-TOF spectra of several species from the S. mitis group has been performed in order to identify single peaks that could be used to improve mass spectrometry-based identification of the respective species. A characteristic peak profile could be identified that unambiguously distinguished the 14 S. pneumoniae isolates studied from 33 nonpneumococcal isolates of the S. mitis group. In addition, specific peak combinations could be assigned to other members of the group. The findings of this study suggest that it is possible to distinguish different species of the S. mitis group by close analysis of their mass peak profiles.

SUBMITTER: Werno AM

PROVIDER: S-EPMC3421814 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Differentiation of Streptococcus pneumoniae from nonpneumococcal streptococci of the Streptococcus mitis group by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Werno Anja M AM Christner Martin M Anderson Trevor P TP Murdoch David R DR

Journal of clinical microbiology 20120620 9

The differentiation of species within the Streptococcus mitis group has posed a problem in the routine diagnostic microbiology laboratory for some time. It also constitutes a major weakness of recently introduced matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) fingerprinting systems. As the phylogenetic resolution of the spectral similarity measures employed by these systems is insufficient to reliably distinguish between the most closely related membe ...[more]

PMID: 22718935

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Project description:Streptococcus suis, particularly S. suis serotype 2 (SS2), is an important zoonotic pathogen causing meningitis in humans worldwide. Although the proper classification of the causative and pathogenic serotype is salutary for the clinical diagnosis, cross-reactions leading to the indistinguishability of serotypes by the current serotyping methods are significant limitations. In the present study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of extracted peptides was developed to improve the classification of serotype of S. suis. The peptide mass fingerprint (PMFs) database of S. suis was generated from the whole-cell peptides of 32 reference strains of S. suis isolates obtained from pigs. Thirty-two human S. suis isolates from clinical cases in Thailand were used to validate this alternative serotyping method in direct comparison to the multiplex (m)PCR approach. All reference strains, representing 32 serotypes of S. suis, exhibited their individual PMFs patterns, thus allowing differentiation from one another. Highly pathogenic SS2 and SS14 were clearly differentiated from the otherwise serologically closely related SS1/2 and SS1, respectively. The developed MALDI-TOF-MS serotyping method correctly classified the serotype in 68.8% (22/32) of the same serotype isolates generated from the PMFs database; while the validity for the clinical human isolates was 62.5% (20/32). The agreement between the MALDI-TOF-MS and mPCR serotyping was moderate with a Kappa score of 0.522, considering that mPCR could correctly serotype up to 75%. The present study demonstrated that PMFs from the developed MALDI-TOF-MS-based method could successfully discriminate the previously indistinguishable highly pathogenic SS2 and SS14 from SS1/2 and SS1, respectively. Moreover, this serotyping method distinguished pathogenic SS6, and so is an alternative approach of choice to rapidly and reliably serotype clinically pathogenic S. suis isolates.

Dataset Information

Differentiation of Streptococcus pneumoniae from nonpneumococcal streptococci of the Streptococcus mitis group by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Publications

Differentiation of Streptococcus pneumoniae from nonpneumococcal streptococci of the Streptococcus mitis group by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Similar Datasets

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