Chapter Ten - Salmonella

Abstract

Salmonella, as a group, are facultatively anaerobic, non-spore-forming, Gram-negative bacilli. Natural reservoirs of Salmonella are domestic and wild animals, including poultry, swine, cattle, birds, dogs, rodents, tortoises, turtles and cats. Humans also serve as a natural host. The most common source of transmission of Salmonella seems to be the consumption of contaminated poultry and meat products. Contamination of meat products particularly occurs when exposed to faecal matter during slaughter. Once the meat is contaminated, improper storage or undercooking allows Salmonella to proliferate. When Salmonella are excreted in faeces, contamination of food and water permits transmission of the infection to humans. Person-to-person, faecal–oral transmission does occur and has been a problem in health care facilities traced to inadequate hand washing. Moreover there are three clinically distinguishable forms of salmonellosis in humans. These include gastroenteritis, enteric fever and septicaemia. There is increasing evidence that Salmonella is associated with biofilms and that regrowth of salmonellae in the form of a biofilm in potable water distribution systems and water storage containers is possible. In light of the documented evidence, standard disinfection used in drinking water treatment procedures is active against salmonellae, although there is some evidence that these bacteria are more resistant to inactivation than coliforms.