Fluorescence Characterization of Clinically-Important Bacteria (original) (raw)
Related papers
Handheld Multispectral Fluorescence Imaging System to Detect and Disinfect Surface Contamination
Sensors
Contamination inspection is an ongoing concern for food distributors, restaurant owners, caterers, and others who handle food. Food contamination must be prevented, and zero tolerance legal requirements and damage to the reputation of institutions or restaurants can be very costly. This paper introduces a new handheld fluorescence-based imaging system that can rapidly detect, disinfect, and document invisible organic residues and biofilms which may host pathogens. The contamination, sanitization inspection, and disinfection (CSI-D) system uses light at two fluorescence excitation wavelengths, ultraviolet C (UVC) at 275 nm and violet at 405 nm, for the detection of organic residues, including saliva and respiratory droplets. The 275 nm light is also utilized to disinfect pathogens commonly found within the contaminated residues. Efficacy testing of the neutralizing effects of the ultraviolet light was conducted for Aspergillus fumigatus, Streptococcus pneumoniae, and the influenza A ...
Rapid Detection of Three Common Bacteria Based on Fluorescence Spectroscopy
Sensors, 2022
As an important part of environmental water quality monitoring, efficient bacterial detection has attracted widespread attention. Among them, LIF (laser-induced fluorescence) technology has the characteristics of high efficiency and sensitivity for bacterial detection. To simplify the experimental process of bacterial detection, fluorescence emission spectra of E. coli (Escherichia coli) and its deactivated controls, K. pneumoniae (Klebsiella pneumoniae) and S. aureus (Staphylococcus aureus), were analyzed with fluorescence excitation by a 266 nm laser. By analyzing the results, it was found that the dominant fluorescence peaks of bacterial solutions at 335~350 nm were contributed by tryptophan, and the subfluorescence peaks at 515.9 nm were contributed by flavin; besides, K. pneumoniae and S. aureus had their own fluoresces characteristics, such as tyrosine contributing to sub-fluorescence peaks at 300 nm. The three species of bacteria can be differentiated with whole fluorescence ...
Journal of Biosensors & Bioelectronics
A real-time detection and monitoring (RTDM) of microbial contamination on solid surfaces is mandatory in a range of security, safety and bio-medical applications where surfaces are exposed to accidental, natural or intentional microbial contamination. This work presents a new device, the BC-Sense, which allows a rapid and user-friendly RTDM of microbial contamination on various surfaces while assessing the decontamination kinetics and degree of cleanliness. The BC-Sense LIDAR (Light Detection and Ranging) device uses the Laser-Induced Fluorescence (LIF) method based on dual wavelength sensing with multispectral pattern recognition system to rapidly detect microbial contamination on a solid surface. Microbial simulants (bacteria, bacterial spores, fungal conidia and virus) were spread at varying concentrations on a panel of solid surfaces which were assessed by BC-Sense. The spectra of dead and living E. coli showed differences at various sensing wavelengths. The limit of detection (LoD) of E. coli and MS2 virus was 2.9 × 10 4 and 9.5 × 10 4 CFU and PFU/cm 2 , respectively. Random samples (n=200) tested against a training dataset (n=800) were optimally discriminated for contamination versus background with a threshold of predicted response (PR) >0.55 and <0.4, respectively. Decontamination kinetics on copper surface showed a complete disappearance of fluorescence in 1 min with MS2 versus >10 min with spores and E. coli.
Bioluminescent System of Luminous Bacteria for Detection of Microbial Contamination
Journal of Siberian Federal University. Biology, 2018
Microbial contamination is usually analyzed using luciferin-luciferase system of fireflies by the detection of adenosine-5'-triphosphate (ATP). There is an opportunity to assess the bacterial contamination of various objects based on a quantitative analysis of other nucleotides. In the present study, a bioluminescent enzyme system of luminous bacteria NADH:FMN-oxidoreductase (Red) and luciferase (BLuc) was investigated to understand if it can be used for quantitative measurements of bacterial cells by nicotinamide adenine dinucleotide (NADH) and flavin mononucleotide (FMN) detection. To increase the sensitivity of bioluminescent system to FMN and NADH, optimization of assay conditions was performed by varying enzymes and substrates concentrations. The lowest limits of detection were 1.2 nM FMN and 0.1 pM NADH. Escherichia coli cells were used as a model bacterial sample. FMN and NADH extraction was made by destructing cell membrane by ultrasonication. Cell suspension was added into the reaction mixture instead of FMN and NADH, and light intensity depended on number of bacterial cells in the reaction mixture. Centrifugation of sonicated sample as an additional step of sample preparation did not improve the sensitivity of method. The experimental results showed that Red and BLuc system could detect at least 800 thousand bacterial cells mL-1 by determining concentration of NADH extracted from lysed cells, while 3.9 million cells mL-1 can be detected by determining concentration of FMN.
Rapid detection of Escherichia coli in water using a hand-held fluorescence detector
Water Research, 2010
The quantification of pathogenic bacteria in an environmental or clinical sample commonly involves laboratory-based techniques and results are not obtained for 24-72 h after sampling. Enzymatic analysis of microbial activity in water and other environmental samples using fluorescent synthetic substrates are well-established and highly sensitive methods in addition to providing a measure of specificity towards indicative bacteria. The enzyme b-D-glucuronidase (GUD) is a specific marker for Escherichia coli and 4-methylumbelliferone-b-D-glucuronide (MUG) a sensitive substrate for determining the presence of E. coli in a sample. However, currently used procedures are laboratory-based and require bench-top fluorimeters for the measurement of fluorescence resulting from the enzymesubstrate reaction. Recent developments in electronic engineering have led to the miniaturisation of fluorescence detectors. We describe the use of a novel hand-held fluorimeter to directly analyse samples obtained from the River Thames for the presence of E. coli. The results obtained by the hand-held detector were compared with those obtained with an established fluorescent substrate assay and by quantifying microbial growth on a chromogenic medium. Both reference methods utilised filtration of water samples. The miniaturised fluorescence detector was used and incubation times reduced to 30 min making the detection system portable and rapid. The developed hand-held system reliably detected E. coli as low as 7 cfu/mL river water sample. Our study demonstrates that new handheld fluorescence measurement technology can be applied to the rapid and convenient detection of bacteria in environmental samples. This enables rapid monitoring to be carried out on-site. The technique described is generic and it may, therefore, be used in conjunction with different fluorescent substrates which allows the assessment of various target microorganisms in biological samples.
Biosensors and Bioelectronics, 1996
There is a widespread need for commercial instrumentation for the rapid and inexpensive detection of microbial contamination of food, industrial waste water and clinical samples. A large number of detection methods have been developed utilizing the optical, electrochemical, biochemical and physical properties of microorganisms.
Reagentless detection of microorganisms by intrinsic fluorescence
Biosensors and Bioelectronics, 2003
Quick and accurate detection of microbial contamination is accomplished by a unique combination of leading-edge technologies described in this and the accompanying paper. In this contribution, a hand-held prototype instrument is described which is capable of statistically sampling the environment for microbial contamination and determining cell viability. The technology is sensitive enough to detect very low levels ( Â/20 cells/cm 2 or cm 3 ) of microbes in seconds. #
Journal of Biomedical …, 2006
A scanning optical system for the detection of bacteria on meat surfaces based on fluorescence lifetime and intensity measurements is described. The system detects autofluorescent light emitted by naturally occurring fluorophores in bacteria. The technique only requires minimal sample preparation and handling, thus the chemical properties of the specimen are preserved. This work presents the preliminary results obtained from a time-resolved fluorescence imaging system for the characterization of a nonpathogenic gram-negative bacteria, Pseudomonas fluorescens. Initial results indicate that the combination of fluorescence lifetime and intensity measurements provides a means for characterizing biological media and for detecting microorganisms on surfaces.
Microbial biofilm detection on food contact surfaces by macro-scale fluorescence imaging
Journal of Food Engineering, 2010
Hyperspectral fluorescence imaging methods were utilized to evaluate the potential detection of pathogenic bacterial biofilm formations on five types of food contact surface materials: stainless steel, highdensity polyethylene (HDPE), plastic laminate (Formica), and two variations of polished granite. The main objective of this study was to determine a minimal number of spectral fluorescence bands suitable for detecting microbial biofilms on surfaces commonly used to process and handle food. Spots of biofilm growth were produced on sample surfaces by spot-inoculations of pathogenic Escherichia coli O157:H7 and Salmonella followed by room temperature storage for 3 days. Subsequently, hyperspectral fluorescence images were acquired from 421 to 700 nm using ultraviolet-A excitation. Both E. coli O157:H7 and Salmonella biofilms emitted fluorescence predominantly in the blue to green wavelengths with emission maxima at approximately 480 nm. A single-band image at 559 nm was able to detect the biofilm spots on stainless steel. On HDPE and granite, algorithms using different two-band ratios provided better separation of the biofilm spots from background areas than any single-band images did. The biofilm spots on stainless steel, HDPE, and granite could be detected with overall detection rate of 95%. On Formica, too many false positives were present to accurately determine an effective biofilm detection rate. This may have been due to the lower cell population density that was observed for the biofilm spots grown on Formica (approximately 4.3-6.4 log cfu cm À2 ) as compared to the other surfaces. These findings can be incorporated into developing portable hand-held imaging devices for sanitation inspection of food processing surfaces.