Rapid detection of coliform bacteria using a lateral flow test strip assay

Coliform bacteria in foods are enumerated at food processing plants and are used as sanitary and quality indicators. To detect coliform bacteria rapidly, seven Lateral Flow Test Strips (LFTSs) that can detect the genera Aeromonas, Citrobacter, Enterobacter, Hafnia, Klebsiella/Raoultella, Pantoea and Serratia were developed. For 55 tested food isolates, the detection rate of each individual LFTS assay was only 38% to 76%, but the detection rate of the 7 combined assays was 100%. For 38 culture collection strains, including clinical isolates, each individual LFTS assay had a detection rate of only 18% to 76%, but the 7 assays in combination had a detection rate of 89%. A feasibility study conducted on 20 types of meat (beef, chicken and pork) indicated that the LFTS assays detected coliform bacteria from 3 types of meat without incubation and from all other meats after 8 h of incubation. LFTS assays showed a positive signal when the meat was spoiled by more than 4.9 log(10) (cfu/g) coliform bacteria. A longer incubation time led to increased bacterial counts, more positive LFTSs (1.8 at 8 h and 4.6 at 24 h) and a greater maximal signal intensity (1, 366 at 8 h and 2, 678 at 24 h). Thus, LFTSs of coliform bacteria have great potential for the rapid determination of food freshness as well as food sanitation status.