Pseudomonas azotoformans Belonging to Pseudomonas fluorescens Group as Causative Agent of Blue Coloration in Carcasses of Slaughterhouse Rabbits

The study describes the finding of an abnormal blue-tinged color found on rabbit carcasses in the refrigeration cell of two butcher shops in Apulia Region. The carcasses were from an industrial rabbitry for production of meat with a regularly authorized slaughterhouse. Pseudomonas azotoformans, a microorganism included in Pseudomonas fluorescens group, was isolated from samples collected by the altered carcasses, showing the growth of uniform bacterial colonies with fluorescent pigmentation. The bacterium was also isolated from an additional water sample and from the labelling gun collected in the slaughterhouse, whilst the knives used for slaughtering resulted negative. Chromatic alteration was experimentally reproduced on new carcasses using a 108 cfu/mL bacterial suspension prepared with the isolated strain. Due to their resistance characteristics, members of P. fluorescens group are very difficult to eradicate once introduced into the production environment. Therefore, their presence, even if not considered a public health problem, should be monitored by food industry operators in self-control plans.