Use of FTIR spectroscopy to distinguish between capsular types and capsular quantities in Streptococcus pneumoniae

Abstract

Fourier transform infrared (FTIR) spectroscopy has shown remarkable ability in distinguishing between bacterial species and identifying bacterial colony structures, when used in tandem with methods such as cluster analysis, principal component analysis, or linear discriminant analysis. The present work was aimed to evaluate the potential of FTIR-microscopy (FTIR-MSP) to distinguish between different serotypes and capsular quantities of Streptococcus pneumoniae. In general, the results obtained have consistently proven that the spectral information at the region 900-1,185 cm(-1) was sufficient to distinguish between various pneumococcal serotypes. Moreover, the method was able to differentiate between S. pneumoniae phase variants on the basis of their relative carbohydrate content. The unsupervised cluster analysis of the samples showed differences, not only in the carbohydrate content, but also in the region 1,350-1,480 cm(-1), which is dominated by absorptions due to lipids and phospholipids. This approach proved to be useful for the distinction between S. pneumoniae serotypes and between phase variants, which were shown to acquire different pathogenic capacity.

Pneumococcal Capsules and Their Types: Past, Present, and Future

“…PSs have characteristic Fourier transform infrared spectra, and thus this technique can be used to serotype pneumococci (213). Another approach is to use MS. For instance, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) spectroscopy may be used to serotype PS, as was performed with Streptococcus agalactiae isolates (214).…”

Adhesion and invasion of Streptococcus pneumoniae to primary and secondary respiratory epithelial cells

“…The encapsulated strains included the following: i) The WU2 serotype 3 strain, which has the thickest capsule among all strains tested in the current study, and is considered to be a highly invasive strain (53–55); ii) the D39-LM serotype, which is widely used for studying S. pneumoniae pathogenesis (28); iii) the 6B-RD serotype, which was isolated from the nasopharynx of a healthy child and was previously demonstrated to colonize the nasopharynx but not disseminate to the lungs or any other tissue (56,57); and iv) the 23F-RD serotype, which is considered to be pathogenic, as its capsule was included in the 7 valent conjugate vaccine (58). The unencapsulated strains included the 3.8-DW, which is a derived from WU2 (44) and the R6 strain (45), which was derived from the D39 strain.…”

Chemometrics of Cells and Tissues Using IR Spectroscopy - Relevance in Biomedical Research

“…The various protocols are also required to be suitably modified depending upon whether a sample is fresh, frozen or paraffin embedded to exclude interfering substances . The spectroscopy of microorganisms on the other hand may be simpler (Sahu et al 2006b).Both FTIR and Raman spectroscopy use vibrational spectroscopy and can be used independently or in combination with each other as a means of spectroscopic evaluation of biological samples (Mourant et al 2003b, Krishna et al 2005, Oust et al 2006. The prospective of extending Fiberoptic detection systems to different organs is a future potential (Lucas et al 2005).…”

“…For example, bacterial cells from cultures in log phase are harvested after treatment with chloroform and the media removed by centrifugation. Subsequently they are washed several times in normal saline (without phosphates) and mounted on discs or any IR transparent support for spectra collection (Sahu et al 2006b).…”

“…It has the ability to distinguish between microorganisms depending on their biochemical variation and this has been demonstrated in both bacteria and fungi (Sahu et al 2006b, Salman et al 2011. Similarly, minute changes can occur between the different stages of cancer or malignancy which are difficult to detect even with histochemical analyses.…”