Cellular Light Scattering for the Identification of Bacteria and Its Application to the Identification of Staphylococcus

Abstract

Rapid identification of bacteria is critical in clinical and food safety applications. This paper describes a novel instrument and data analysis method for identifying bacteria based on the measurement of laser light scattering as the beam interacts with bacterial cells suspended in water. A description of the technology is followed by an identification performance study for a set of strains from the genus Staphylococcus (the inclusive target organisms) and a set of non-Staphylococcus strains (the exclusive organisms). Staphylococcus and non-Staphylococcus cells were grown on sheep blood agar (SBA), tryptic soy agar, brain heart infusion (BHI) agar, or Luria-Bertani (LB) agar and identified based on how cells scattered light. Bacteria from the genus Staphylococcus grown on solid media were correctly identified more than 92% of the time. To determine whether the system could also identify bacteria grown in liquid culture, six different Staphylococcus strains and six different non-Staphylococcus strains were grown in tryptic soy broth, BHI broth, or LB broth. This system accurately identified all targeted Staphylococcus samples tested, and no misidentifications occurred. A single-blind identification experiment was also performed on human clinical isolates obtained from the Upper Peninsula Health System. Ninety blind-coded clinical bacterial isolates on SBA were tested to determine whether they were from the genus Staphylococcus. All Staphylococcus were accurately identified, and no misidentifications occurred. This study demonstrated the proof of concept of a novel system that can rapidly and accurately identify bacteria from pure culture based on cellular light-scattering properties.

Petri-plate, bacteria, and laser optical scattering sensor

“…Measuring the intensities of the full 4-π radian of scattered light from single cells was the detection principle where the light scattering phenomenon occurs in a single scattering regime. The system requires the suspension of one type of organism (purified target culture) to avoid the generation of multiple overlapping scatter signatures from mixed cultures since multiple scattering events may interfere with the specific detection of the target ( Haavig et al., 2017 ). Therefore, pure cultures are essential, which could be obtained from isolated colonies from a Petri plate.…”

Rapid Detection System for Hepatitis B Surface Antigen (HBsAg) Based on Immunomagnetic Separation, Multi-Angle Dynamic Light Scattering and Support Vector Machine

“…The confusion matrix built from the resulting cross-validation was used to analyze the performance of the classifier. The mean values of accuracy, precision, sensitivity, specificity, and F-score were evaluated based on (13)(14)(15)(16)(17)(18), and presented in Table. I. The classification accuracy attained by SVM classifier for the identification of HBsAg is 87.76%.…”

“…This work uses immunomagnetic (IM) beads for the separation of HBsAg, and the classification of laser light scattering patterns based on support vector machine (SVM). The light scattering has been used widely in many biomedical devices to predict the physical and chemical characteristics of the sample [15]- [17]. The proposed system for pathogens identification is based on the basic principle of laser light scattering from the IM beads.…”