Optical forward-scattering for detection of Listeria monocytogenes and other Listeria species

Banada, Padmapriya P.; Guo, Songling; Bayraktar, Bülent; Bae, Euiwon; Rajwa, Bartek; Robinson, J. Paul; Hirleman, E. Dan; Bhunia, Arun K.

doi:10.1016/j.bios.2006.07.028

Cited by 127 publications

(127 citation statements)

References 26 publications

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“…2 The results indicated that the individual bacterium tended to form a layered structure rather than a distribution of randomly oriented bacterium, which provided for us a ground on which to model the light-bacteria interactions using a layer model as a first-order approximation. We divided the bacterial colony profile as multiple layers of bacteria with a thickness of ⌬ m, considering the physical dimensions of the individual bacteria and extracellular materials.…”

Section: Amplitude Componentmentioning

confidence: 93%

Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns

Bae

Bai

Aroonnual³

et al. 2010

J. Biomed. Opt.

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Abstract. Bacterial colonies play an important role in the isolation and identification of bacterial species, and plating on a petri dish is still regarded as the gold standard for confirming the cause of an outbreak situation. A bacterial colony consists of millions of densely packed individual bacteria along with matrices such as extracellular materials. When a laser is directed through a colony, complicated structures encode their characteristic signatures, which results in unique forward scattering patterns. We investigate the connection between the morphological parameters of a bacterial colony and corresponding forward scattering patterns to understand bacterial growth morphology. A colony elevation is modeled with a Gaussian profile, which is defined with two critical parameters: center thickness and diameter. Then, applying the scalar diffraction theory, we compute an amplitude modulation via light attenuation from multiple layers of bacteria while a phase modulation is computed from the colony profile. Computational results indicate that center thickness plays a critical role in the total number of diffraction rings while the magnitude of the slope of a colony determines the maximum diffraction angle. Experimental validation is performed by capturing the scattering patterns, monitoring colony diameters via phase contrast microscope, and acquiring the colony profiles via confocal displacement meter.

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Section: Amplitude Componentmentioning

confidence: 93%

Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns

Bae

Bai

Aroonnual³

et al. 2010

J. Biomed. Opt.

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“…words, the diameter variability can introduce variations of the scattering pattern that are significantly dependent on the species we are looking at, however, from our evidences, this does not appear to be a serious impediment to the ability of differentiating the bacterial species, especially by using a machine learning algorithm that can rely on the visual features that remain statistically unchanged (e.g. captured by tools as Zernike moments (Khotanzad and Hong, 1990;Banada et al, 2007)). …”

Section: The Colony Dimension Variability At Fixed Timementioning

confidence: 92%

On the application of optical forward-scattering to bacterial identification in an automated clinical analysis perspective

Minoni

Signoroni

Nassini

2015

Biosensors and Bioelectronics

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The Optical Forward Scattering (OFS) technique can be used to identify pathogens by direct observation of bacteria colonies growing on a culture plate. The identification is based on the acquisition of scattering images from isolated colonies and their subsequent comparison with reference images acquired from known bacteria. The technique has been mainly studied for the identification of pathogens in the food-safety field. This paper focuses on the possibility of extending the applicability of the technique to the field of clinical laboratory automation. This scenario requires that the paradigm of image acquisition at fixed colony-dimension, well established in the food-safety applications, should be substituted by an acquisition at fixed incubation time. As a consequence, the scatterometer must be adjustable in real-time for adapting to the actual features of the bacterial colony. The paper describes an OFS system prototype qualified by the possibility to tune both the laser beam diameter and the acquisition camera field of view.Preliminary experiments on bacteria cultures from pathogens causing infections of the urinary tract show that the proposed approach is promising for the development of an Submitted to Biosensor and Bioelectronics 2 automated bacteria identification station. The new OFS approach also involves an alternative method for building a reference image database for subsequent image analysis.

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“…A machine that functions on biophysical principles, designated BARDOT, was invented and built at Purdue University by our group (1,3,33). BARDOT consists of the following three main parts: (i) a colony locator in which a back-illumination light with a diffuser aids in the localization of the colonies on the plate, (ii) a moving platform that moves the petri dish in the x and y directions, and (iii) a red-diode laser (635 nm; 1 mW; 1-mm diameter) and a complementary metal oxide semiconductor (CMOS) camera that illuminates and captures the image of each colony.…”

Section: Methodsmentioning

confidence: 99%

“…BARDOT uses a 635-nm reddiode laser (1 mW) beam shined onto the center of a bacterial colony on an agar plate, which generates a 2-dimensional luminous forward scatter fingerprint (1). Analyses of BARDOT images involve hundreds of independent parameters and features that are extracted from each scatter pattern to build a database of images for a specific microorganism (2)(3)(4). BARDOT has been used successfully for the detection of multiple bacterial pathogens, including Listeria spp.…”

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confidence: 99%

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Virulence Gene-Associated Mutant Bacterial Colonies Generate Differentiating Two-Dimensional Laser Scatter Fingerprints

Singh

Leprun

Drolia

et al. 2016

Appl Environ Microbiol

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In this study, we investigated whether a laser scatterometer designated BARDOT (bacterial rapid detection using optical scattering technology) could be used to directly screen colonies of Listeria monocytogenes, a model pathogen, with mutations in several known virulence genes, including the genes encoding Listeria adhesion protein (LAP; lap mutant), internalin A (⌬inlA strain), and an accessory secretory protein (⌬secA2 strain). Here we show that the scatter patterns of lap mutant, ⌬inlA, and ⌬secA2 colonies were markedly different from that of the wild type (WT), with >95% positive predictive values (PPVs), whereas for the complemented mutant strains, scatter patterns were restored to that of the WT. The scatter image library successfully distinguished the lap mutant and ⌬inlA mutant strains from the WT in mixed-culture experiments, including a coinfection study using the Caco-2 cell line. Among the biophysical parameters examined, the colony height and optical density did not reveal any discernible differences between the mutant and WT strains. We also found that differential LAP expression in L. monocytogenes serotype 4b strains also affected the scatter patterns of the colonies. The results from this study suggest that BARDOT can be used to screen and enumerate mutant strains separately from the WT based on differential colony scatter patterns. IMPORTANCEIn studies of microbial pathogenesis, virulence-encoding genes are routinely disrupted by deletion or insertion to create mutant strains. Screening of mutant strains is an arduous process involving plating on selective growth media, replica plating, colony hybridization, DNA isolation, and PCR or immunoassays. We applied a noninvasive laser scatterometer to differentiate mutant bacterial colonies from WT colonies based on forward optical scatter patterns. This study demonstrates that BARDOT can be used as a novel, label-free, real-time tool to aid researchers in screening virulence gene-associated mutant colonies during microbial pathogenesis, coinfection, and genetic manipulation studies.

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Optical forward-scattering for detection of Listeria monocytogenes and other Listeria species

Cited by 127 publications

References 26 publications

Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns

Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns

On the application of optical forward-scattering to bacterial identification in an automated clinical analysis perspective

Virulence Gene-Associated Mutant Bacterial Colonies Generate Differentiating Two-Dimensional Laser Scatter Fingerprints

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