Early Events in the Pathogenesis of Avian Salmonellosis

Abstract

Salmonellae are gastrointestinal pathogens of man and animals. However, strains that are host-specific avian pathogens are often avirulent in mammals, and those which are nonspecific are commensal in poultry. The objective of this study was to determine whether host specificity was exhibited by bacterial abilities to invade epithelial cells or resist leukocyte killing. In this study, leukocytes isolated from humans and chickens were used to kill Salmonella in vitro. Both Salmonella pullorum, an avian-specific serotype, and Salmonella typhimurium, a broad-host-range serotype, were sensitive to killing by polymorphonuclear leukocytes isolated from both species. Both serotypes replicated in cells of the MQ-NCSU avian-macrophage cell line. In contrast, S. pullorum was noninvasive for cultured epithelial Henle 407, chick kidney, chick ovary, and budgerigar abdominal tumor cells. In the bird challenge, however, S. typhimurium rapidly caused inflammation of the intestinal mucosa, but S. pullorumpreferentially targeted the bursa of Fabricius prior to eliciting intestinal inflammation. Salmonella serotypes which cause typhoid fever in mice have been shown to target the gut-associated lymphoid tissue. Observations from this study show that S. pullorum initiated a route of infection in chicks comparable to the route it takes in cases of enteric fever.

Quantitative distribution and interaction of Salmonella Zega with host cells in visceral organs of chickens infected orally, intraperitoneally and per cloaca

“…Shu-Xuan et al (2008) reported that quantitative studies of the regular distribution pattern for Salmonella Enteritidis in the internal organs of mice after oral challenge by a specific real-time polymerase chain reaction showed higher distribution in the liver and spleen. Salmonella organisms are known to replicate in the reticuloendothelial systems, while lymphoid tissues are targets for Salmonella invasion (Carter and Collins, 1974a and b;Henderson et al, 1999). It has been reported that Salmonella infection of lymphoid tissue can account for the depletion and necrosis of lymphoid follicles of the spleen seen in most Salmonella infections (Henderson et al, 1999).…”

Heterophils are associated with resistance to systemicSalmonella enteritidisinfections in genetically distinct chicken lines

“…This could be due, in part, because broilers typically have fewer numbers of mononuclear cells compared to other types of chickens [31]. It is also possible that the timing was not optimized for monitoring mononuclear migration into the abdominal cavity, since mononuclear cell migration does not peak until four days post-challenge [32] compared to 4 h post-challenge for heterophils. Henderson et al [32] also reported that macrophages were less efficient at killing various Salmonella spp.…”

Avian Colibacillosis and Salmonellosis: A Closer Look at Epidemiology, Pathogenesis, Diagnosis, Control and Public Health Concerns

“…In case of inadequate body defense mechanism, they may lead to second invasion and be localized in other organs, particularly ovary, oviduct, myocardium, pericardium, gizzard, yolk sac and/or lungs [177]. In the bird challenge, S. typhimurium rapidly caused inflammation of the intestinal mucosa, but S. pullorum preferentially targeted the bursa of Fabricius prior to eliciting intestinal inflammation [178]. Pullorum disease manifests itself predominantly as an enteric disease of chickens, while fowl typhoid shows signs of septicemic disease [78].…”