Rapid quantification of coliforms in ready‐to‐eat foods using lateral‐flow immunochromatographic assay

Abstract

The degree of coliform contamination in pastries was estimated based on culturing times until positive results were obtained with the lateral-flow immunochromatographic assay (LFIA). Coliform genera Citrobacter, Cronobacter, Enterobacter, Klebsiella, Kluyvera, Pantoea, Raoultella, and Serratia were detected in spoiled pastries, as established with next-generation sequencing. A lateral-flow test strip was constructed using antibodies recognizing the above genera. The culture times required for positive detection with LFIA were 0, 3, 6, and 9 hr at initial inoculation concentrations of 3.8, 2.8, 1.8, and 0.8 log 10 (cfu/ml), respectively. In pastries contaminated with >5.0, 3.0-5.0, 2.0-3.0 log 10 (cfu/g) coliform bacteria, samples became LFIA-positive from 3, 6, and 9 hr culture, respectively. LFIA showed negative for pastries with <2.0 log 10 (cfu/g) coliform contamination. The quantitative category of initial coliform content before culture was predictable with 87% accuracy. This novel method can be applied to monitor food safety of other ready-to-eat consumables.

Biological Indicators for Fecal Pollution Detection and Source Tracking: A Review

“…First, it shows a strong association with fecal pollution, as it is found in all feces of warm- Since coliforms can be cultured with ease, there are culture-based and culture-independent methods to detect and enumerate coliforms in water. Frequently used culture-based enumeration methods include the (i) classical plate count on violet-red-bile-lactose agar medium [73] or chromogenic media based on the activities of β-D-galactosidase (of coliforms) and β-glucuronidase (of E. coli) [74], (ii) most probable number procedure in lauryl tryptose broth [75] and IDEXX systems, (iii) membrane filtration in selective M-Endo medium [76] and (iv) lateral-flow immune-chromatographic assay using antibodies recognizing coliform genera [77]. Culture-independent methods include (i) real-time PCR targeting the lacZ gene of coliforms [78,79], (ii) fluorescence-based DNA microarray probing E. coli [80], (iii) flow cytometry [81] and (iv) next-generation sequencing or metagenomics that profile all microorganisms, including total/fecal coliforms [82].…”

Fluorescence immunoassay for the targeted determination of traceListeria monocytogenesbased on immunomagnetic separation and CdZnTe quantum dot indication

“…However, the culture and colony-counting method 3 proposed rst and regarded as the gold standard in the eld of bacterial detection is time-consuming and labor-intensive. 4,5 In recent decades, various typical approaches and technologies for detecting pathogenic bacteria have been developed, such as DNA-amplication techniques, like polymerase chain reaction (PCR), [6][7][8] immunological assays, like the enzyme-linked immunosorbent assay (ELISA) 9 and lateral ow immunochromatographic assay (LFIA), 10,11 electrochemical biosensors, 12 and uorescent biosensors. 13 The implementation of uorescent sensing for bacterial detection has garnered signicant interest due to their quantitative nature and high-speed detection.…”