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In order to study the dynamics of avian colibacillosis, commercial broiler chickens were inoculated with a pathogenic Escherichia coli strain (01:K1:H7) into the left caudal thoracic air sac. Chickens were euthanatized at different times from 3 to 48 hr postinoculation and examined for bacterial counts and macroscopic and microscopic lesions. The E. coli strain colonized the air sacs, lungs, and trachea and was recovered from blood and all tested extrarespiratory organs of inoculated birds. A gradual increase in bacterial counts in the trachea, lungs, air sacs, and liver was observed from 3 to 12 hr. Clinical signs and macroscopic lesions of colibacillosis were observed in all inoculated birds. Moderate to severe lesions of airsacculitis, pericarditis, perihepatitis, and splenic hypertrophy were observed. Microscopically, inflammatory cell infiltration, serious to fibrinous exudate, and cellular debris on serosal surfaces were present in the liver, spleen, and air sacs. In air sacs, heterophils were present in low numbers perivascularly 3 hr after inoculation and became more numerous by 24 hr postinoculation. Ultrastructurally, epithelial cells in the air sacs and in air capillary regions of the lung were swollen and vacuolated beginning at 3 hr postinoculation. Bacteria were adherent to and present within the epithelial cells at 3 hr postinoculation and were also seen in phagocytic cells and, rarely, in the connective tissue of these organs at 24 hr postinoculation. These results indicate that both air sacs and lungs can be the portal of entry for E. coli into the systemic circulation, probably via damaged epithelium.

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A total of 645 samples of raw and cooked foods were examined for the presence of Salmonella spp. Salmonella was detected in 43 (6.66%) of the samples. Salmonella was isolated from 24/134 (17.91%) of raw poultry, 3/56 (5.35%) of cooked poultry, 8/101 (7.92%) of raw meat, 2/118 (1.69%) of cooked meat, 1/3 (33.3%) of turkey, 2/5 (40.00%) of quail and 3/38 (7.89%) of vegetables. All samples taken from fish, yogurt, ready‐to‐eat olovieh salad, hamburger, mayonnaise souse and smallgoods were free of Salmonella. Of the 31 strains of Salmonella, 11 different serotypes were separated; among them S. enteritidis (29%) and S. baibouknown (29%) were the most frequent in raw foods. Furthermore, a high proportion of poultry was contaminated with Salmonella. Salmonella spp. were present in a small proportion of cooked foods, that is, they were not killed during the cooking process, or the contamination might have occurred after thermal treatment. These findings have a clear implication for public health, indicating the needs for improvement of hygienic condition in food processing centers. PRACTICAL APPLICATIONS To control and reduce human salmonellosis, periodic surveillance is necessary to determine the occurrence of Salmonella in various foods.Therefore, this study investigated the presence of Salmonella serovar in raw and cooked foods in one of the most populated provinces in Iran. The data presented here will help the food industry, regulatory agencies and health policymakers target sectors which need additional monitoring or more effective control. As no documented information is provided on the sources of disease in Iran, this report may assist in further assessment of the sources of Salmonella in the human population. The number of salmonellosis cases will decrease following the introduction of mandatory Hazard Analysis and Critical Control Point (HACCP) in food industries. Hence, this study may convince governmental authority and private sectors to apply the HACCP system to ensure food safety. This study also underlines the need for adequate consumer protection against pathogens transmitted by foods in Iran.