Chlorine Induces Physiological and Morphological Changes on Chicken Meat Isolates.

Broiler chickens frequently become colonized by species. As a consequence, , can enter the poultry meat supply chain and represents a significant risk for human public health. A number of on-farm biosecurity and processing measures are used to mitigate the load of on chicken meat. In many countries, chlorine is commonly used as a biocide in processing plants to reduce bacterial loads on poultry carcasses but there is limited evidence of its effectiveness on . In this study, 116 isolates (89 and 27 ) were isolated from poultry meat carcasses prior to the inside/outside wash step and used in assays exploring the efficacy of chlorine. A high proportion of isolates exhibited MIC and MBC values of 128 ppm but organic material present in the broth likely affected this result. Thus, additional bactericidal assays (time kill and chlorine inactivation) were used to characterize the response of isolates to different concentrations of chlorine. At 10 CFU, was found to be highly sensitive to concentrations of chlorine and was inhibited at low concentrations (0.2-2.0 ppm). At a higher bacterial load (10 CFU), variation in the response of different isolates was observed. One isolate was growth inhibited at 1.8 ppm while another required 16 ppm. At 10 CFU, could be resuscitated following exposure to chlorine highlighting a potential limitation of chlorine use. Analysis of UV leakage indicated that high chlorine concentrations resulted in increased 280 nm absorbance values suggesting bacterial membrane damage. Scanning electron and transmission electron microscopy were performed to characterize the morphological effects of chlorine exposure. Some effects of chlorine exposure included changes in shape (coccoid, or elongated), cellular degeneration, and shriveled bacterial cells. Interestingly, with normal morphology were also observed in the chlorine exposed group and represent a population of cells that could be resuscitated. This study is useful for the chicken meat industry and provides data for future optimization of chlorine use in reducing loads.