Proteomic variation and diversity in clinical Streptococcus pneumoniae isolates from invasive and non-invasive sites.

Mustapha Bittaye,Ken Forbes,Phil Cash

doi:10.1371/journal.pone.0179075

Abstract

Streptococcus pneumoniae is responsible for a variety of invasive and non-invasive human infections. There are over 90 serotypes of S. pneumoniae differing in their ability to adapt to the different niches within the host. Two-dimensional gel electrophoresis was used to discriminate clinical S. pneumoniae isolates recovered from either blood cultures (invasive site isolates) or other sites, including sputum, tracheal aspirate, ear, eye and skin swabs (non-invasive site isolates). Global protein expression profiles for five invasive site and six non-invasive site isolates representing five different serotypes (serotypes 4, 6, 9, 14 and 23) were obtained for each isolate and combined into a single data set using Progenesis SameSpots™ software. One-hundred and eighty six protein spots (39% of the protein spots in the dataset) differed significantly (ANOVA, p<0.05) in abundance between the invasive site (101 upregulated protein spots) and non-invasive site (85 upregulated protein spots) isolates. Correlations between the bacterial proteomes and their sites of isolation were determined by Principal Component Analysis (PCA) using the significantly different protein spots. Out of the 186 variable protein spots, 105 exhibited a serotype-associated pattern of variability. The expression of the remaining 81 protein spots was concluded to be uniquely linked to the site of bacterial isolation. Mass spectrometry was used to identify selected protein spots that showed either constant or differential abundance levels. The identified proteins had a diverse range of functions including, capsule biogenesis, DNA repair, protein deglycation, translation, stress response and virulence as well as amino acid, carbohydrate, lipid and nucleotide metabolism. These findings provide insight on the proteins that contribute towards the adaptation of the bacteria to different sites within the host.

Highlights

IntroductionStreptococcus pneumoniae ( known as the pneumococcus) is a significant human pathogenic bacterium that remains a leading cause of morbidity and mortality worldwide
Streptococcus pneumoniae is a significant human pathogenic bacterium that remains a leading cause of morbidity and mortality worldwide
Comparative proteomics of clinical Streptococcus pneumoniae isolates effects on proteome [13,21] and to ensure sufficient material were obtained for the proteomic analysis

Summary

Introduction

Streptococcus pneumoniae ( known as the pneumococcus) is a significant human pathogenic bacterium that remains a leading cause of morbidity and mortality worldwide. Migration of the bacterium across the respiratory epithelium into the blood system and eventually the cerebro-spinal fluid (CSF) leads to the development of severe life-threatening, invasive pneumococcal diseases (IPDs) such as sepsis and meningitis [2]. The lack of a universal vaccine against the many circulating pneumococcal serotypes, as well as the widespread prevalence of antibiotic resistance, present specific challenges for disease control and management [5]. These obstacles are compounded further by a lack of rapid, sensitive, and specific diagnostic tests for IPD

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Results

Conclusion