Pathogenicity of Salmonella enteritidis in poultry.

Salmonella enteritidis is a common pathogen of all species of mammals and fowls. The recent increase in the number of outbreaks of food poisoning due to S. enteritidis in man was epidemiologically analysed, and it was considered that contaminated eggs or egg products were the major source of this infection. To assist in prevention and eradication of human food poisoning many investigators have studied the pathogenicity of S. enteritidis in poultry. Gross pathological observations after natural and experimental infections with S. enteritidis in poultry revealed that this organism may cause systemic infection in chicks and laying hens accompanied by prolonged faecal shedding. Some variations in the mortality rates, clinical symptoms, faecal shedding and frequency of production of contaminated eggs were observed in the chicks and hens experimentally infected with S. enteritidis isolates. Choice of bacterial strain, phage type, age of bird and inoculum size may affect the outcome of an infection. Moreover, isolation of the organisms from the ovaries, oviducts and egg contents indicates the possibility of transovarian infection of S. enteritidis in chickens. Some virulence factors associated with S. enteritidis are also reviewed in the present paper.