Epidemiological study of the genus Aeromonas by means of molecular techniques in different stages of bovine slaughter

Abstract

The harvest of livestock and the subsequent processing of raw meat and meat products is a process that will consistently produce safe meat and meat products in the microbiological point of view for the public consuming, provide that the meat is produced and handled safely prior to consumption. However, history has shown that bacterial pathogens may evade even the best efforts to eliminate them by industry and consumers.The increasing number and severity of food-poisoning outbreaks world-wide has increased public awareness about the safety consumption of meat and meat products. Meat is highly perishable food product which, unless correctly stored, processed, packed and distributed, spoils quickly and becomes hazardous for human health due to microbial multiplication, besides it can act as a vehicle in the transmission of pathogens.Some studies show that the group of bacteria most involved in meat spoilage includes Pseudomonas, Acinetobacter/Moraxella, Aeromonas, Alteromonas putrefaciens, Lactobacillus e Brochothrix thermosphacta. Pathogenic bacteria of most concern include Escherichia coli O157:H7, Salmonella spp, Listeria monocytogenes, Campylobacter, Clostridium botulinum, C. perfringens, Staphylococcus aureus, Aeromonas hydrophila e Bacillus cereus.Among the mentioned ones, the genus Aeromonas has been considered important pathogens to warm- and cold-blooded animals. Recent works has been enphasized their emergence as primary pathogens related to a wide range of local and systemic infections, even in immunocompetent hosts. Aeromonas spp can be found in soil, fresh and saline water, drinking water and animal faeces. They also have been isolated from different kinds of food, such as fish, milk, meat and meat products, ice-cream, cheeses, lettuce and other salad leaves.For being bacteria proceeding from the water and other environments, Aeromonas spp encounter a range of environmental changes that include acid and temperature stresses. However, the ability to adapt to a wide variety of environments and the fact of having virulence factors accounts for their threat as a human pathogen. Some works already demonstrated the presence of Aeromonas spp in meat and meat products, but with difficulties to establish their real origin or source of contamination among the different stages of slaughter, doubts that can be settled with the use of studies involving molecular epidemiology.In sight of the displayed, the study aims at the evaluation of possible sources of contamination of bovine meat by aeromonas and the possible forms of dissemination of these microorganisms in the slaughter process analyzing the following: corral water; supplying water; surface of the animal skin still dried; surface of the skin of the forequarter and hindquarter of the carcass after washing process by aspersion; muscular surface of the forequarter and hindquarter of the carcass; residuary water from the washing of the carcass; ready meat for commercialization; surface of the hands of the handlers; environment of the slaughter room; surface of the knives used in the slaughter room and intestinal contents. (AU)