Direct microscopic observation and visualization of Campylobacter jejuni viability on chicken skin
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A method to detect viability of Campylobacter jejuni on chicken skin was developed by employing confocal laser scanning laser microscopy (CSLM) visualization of Campylobacer jejuni transformed with Pcgfp plasmid (GFP-Campylobacter) exposed to 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), a redox dye, which is taken up, reduced to CTC-formazan, and accumulated intracellularly in respiratory active cells. The data indicated that GFP-Campylobacter remaining on the chicken skin surface after rinsing were mostly located in crevices, entrapped inside feather follicles with water and also entrapped in the surface water layer. Most of the viable cells were entrapped with water in the skin crevices and feather follicles. The population of C. jejuni decreased during storage at 25°C for 24hr. There was no effect of 25°C storage on viability of C. jejuni located 20-30µm beneath the chicken skin. The log10 population of C. jejuni on chicken skin stored at 4°C slightly increased from 0hr to 72hr. The viable cells of GFPC. jejuni located at the surface and 20-30µm beneath the chicken skin increased. Live and dead campylobacters are initially retained with water on the skin and penetrate into the skin with time. Chicken skin provides a suitable environment for campylobacter to survive and grow at 25°C and 4°C, respectively. The effectiveness of chlorine, acidified sodium chlorite and peracetic acid on C. jejuni viability on chicken skin were determined. All sanitizers were equally effective in reducing C. jejuni on chicken skin. The effectiveness of these sanitizers in killing C. jejuni on chicken skin at different locations could not be differentiated in statistical analysis. The detection of live cells after treatment by direct microscopic count at deeper locations has a limitation because of the low number of cells. However, elimination C. jejuni from chicken skin was not achieved as shown by direct microscopic count and plate count.