ABSTRACT
Specific obligatory bacterial pathogens may be limited to a relatively small number of bacteria, and even these frequently exploit damage to the intestinal mucosa in terms of clinically relevant infections and disease. For example, clinically asymptomatic salmonellae in poultry, which cause small reductions in growth rate and feed efficiency that are impossible to measure under commercial conditions, are largely relegated to a category of ‘opportunistic’ pathogens by most poultry veterinarians. Nevertheless, these salmonellae are obligatory pathogens, deriving nutrients and energy sources primarily from the host. In fact, the relatively unusual characteristic of Salmonella spp. to utilize tetrathionate as an energy source allows salmonellae to prosper in the context of enteric inflammatory secretions, regardless of the cause of the inflammatory insult. This ability of salmonellae to exploit the intestinal mucosa of a host with any type of inflammatory bowel disease has been described, showing that tetrathionate leakage led to markedly increased proliferation and disease within the enteric mucosa and submucosa (Thiennimitr et al., 2012; Santos et al., 2003; Winter and Bäumler, 2011; Winter et al., 2010). Nevertheless, the principal problem for poultry producers in regard to infections with salmonellae are those of food-borne illness in humans, linked to origins of undercooked or mishandled poultry products. The large numbers of serotypes have limited the efficacy of currently available vaccines to protect from all Salmonella serotypes (Kuttappan et al., 2013; Boyle et al., 2007; Ohl and Miller, 2001). These topics have been well reviewed elsewhere and the reader is referred to several excellent reviews on this subject (Holt et al., 1999; Cox and Pavic, 2010; Thiennimitr et al., 2012). Moreover, the highly pathogenic serotypes/ biotypes of salmonellae for poultry, Salmonella Pullorum and Salmonella Gallinarum, causing pullorum disease and fowl typhoid, respectively, are largely controlled by constant surveillance and eradication in developed countries (Shivaprasad and Barrow, 2008; Gast, 2008). While these particular salmonellae are capable of causing non-zoonotic but severely pathogenic salmonellosis in poultry without predisposing conditions, they are well reviewed in a variety of sources (Shivaprasad and Barrow, 2008; Gast, 2008; HernándezReyes and Schikora, 2013).
