Spectroscopic Imaging for Detection and Discrimination of Different E. Coli Strains

Abstract

Food contaminations with E. coli bacteria are a major concern for public health. Current techniques for detection are based on sample extractions, time-consuming sample preparations, and labor intensive analyses. Because some strains can be toxic at a level of tens of bacteria and some are not harmful at all, a method of colony localization and strain classification must be developed. In this study we present first results that are based on Fourier transform infrared (FT-IR) spectroscopy and FT-IR imaging. Due to the chemical similarity of different E. coli strains, the acquired spectra show a strong resemblance. It is demonstrated here that based on a correlation analysis samples of the same strain are classified as such and that different strains can be discriminated. The next step is to move from single-spot analyses towards spectroscopic imaging--a technique that facilitates detection of localized bacteria colonies. However, the sheer amount of data acquired in short periods of time prevents many chemical imaging techniques from being feasible for online sensing or for screening extended areas. To improve the time resolution, a data compression approach based on three-dimensional wavelet compression has been applied. It is shown that even with slight compression computation times can be cut down by over an order of magnitude while preserving enough information for localization and classification.

Detection and Classification of Live and DeadEscherichia coliby Laser-Induced Breakdown Spectroscopy

“…T echnologies developed for the detection and identification of microorganisms, particularly bacteria, are of great concern in many areas of research, especially in the search for signs of life on the inner planets of the Solar System (Gilbert et al, 2009;Davis et al, 2012;Hamasha et al, 2013). A fundamental issue with the discovery of signs of life in the context of space exploration missions is that potential habitable planets can be contaminated by Earth life signatures (forward contamination), which in turn can be falsely registered as alien life (Crawford, 2005).…”

“…As a result, space agencies invest a great deal of time and effort to analyze and interpret the microbiome of spacecraft and associated clean rooms with regard to planetary protection (La Duc et al, 2003;Moissl-Eichinger et al, 2013). Many microscopy, genetic, as well as antibody-based methods are often used for the detection of bacteria (Nogva et al, 2003;Nocker et al, 2006;Gilbert et al, 2009). While these methods can yield accurate results, they also suffer from several drawbacks and are time consuming.…”

Microspectroscopic investigation of the membrane clogging during the sterile filtration of the growth media for mammalian cell culture

“…1, which appears to be a protein spectrum at first glance. However, a careful examination of the spectrum reveals that it exhibits typical features of whole cellular IR bands where detailed assignments have been reported in a number of literatures [11][12][13][14][15][16][17][18]. In particular, the IR spectrum of the particles matches excellently with an IR spectrum of bacteria [17].…”

An Overview of the Evolution of Infrared Spectroscopy Applied to Bacterial Typing

“…Sulphate and thiosulphate reducing bacteria Genus FTIRS, FTIRS-ATR HCA, PCA [16,17] Alicylobacillus Genus FTIRS PCA, SIMCA [20] Strain FTIRS-HATR LDA, PCA [75] Photorhabdus Genus FTIRS-ATR HCA, PCA [18] Xenorhabdus Genus FTIRS-ATR HCA, PCA [18] Arcanobacterium Genus FTIRS ANN [19] Actinomyces Genus FTIRS ANN [19] Trueperella Genus FTIRS ANN [19] Species FTIRS ANN [19] Bacillus Genus FTIRS PCA, SIMCA [20] Species FTIRS, FTIRS-ATR, Diffuse Reflectance-FTIRS PCA, HCA, DFA, CVA, SIMCA [26][27][28][29][30]49,50,54,55] Vegetative/Sporulated FTIRS PCA, CART [83] Escherichia Genus FTIRS-ATR HCA, PCA [18] Species FTIRS, FTIRS-ATR HCA, ANN, PCA, SIMCA, CVA [49][50][51][52][53][54]86,92] Escherichia coli Sequence type FTIRS, FTIRS-ATR PC-DFA, PLSDA, HCA, SIMCA [67,68] Strain FTIRS PCA, SIMCA, CVA [49,50,52,73] MLVA profile FTIRS HCA, CVA [72] Listeria spp. Species FTIRS, FTIRS-ATR, FTIR microspectroscopy CVA, ANN, SCDA, PLSRDA, PCA [5,[21][22][23][24][25]…”

“…Several E. coli strains were correctly identified and/or discriminated by FTIRS and appropriate chemometric methods namely, PCA, SIMCA and CVA. [49,50,52,73] Five strains of the epidemic Canadian methicillin-resistant S. aureus (MRSA) were discriminated by PCA and k-nearest neighbor (KNN) algorithm with 87.8 and 97% of correct assignments, respectively. [74] Alicyclobacillus strains, [75] epidemic clones of L. monocytogenes [76] and S. enterica serovar enteritidis [77] outbreaks strains were also successfully discriminated by this technique.…”