Investigation of Antibiotic Resistance in Bacteria Isolated from the Contents and Shell of Industrial Eggs in Qom City, Iran

Background and Objectives: Egg directly affects family nutrition health. The main contaminants of this product is presence of pathogenic bacteria. The purpose of this study was to evaluate the antibiotic resistance of Salmonella, Escherichia coli, and Staphylococcus aureus. Methods: After culturing and isolation processes, S. aureus, E. coli, and Salmonella bacteria were isolated from contents and shell of eggs. Then, antibiotic resistance was determined by agar disk diffusion method. Results: In this study, 22% of the egg shell samples were infected with S. aureus, 4% with E. coli, and 5% with Salmonella, also, 2% of contents samples were infected with S. aureus, 1% with E. coli, and 1% with Salmonella. In evaluation of antibiotic resistance patterns of bacteria isolated from content, the highest resistance in S. aureus was to ampicillin and gentamicin and in E. coli isolates was to ampicillin, clindamycin, and penicillin. Salmonella isolates showed resistance to all the antibiotics used. In evaluation of antibiotic resistance patterns of bacteria isolated from shell, S. aureus isolates showed the highest resistance to clindamycin, and penicillin, in E. coli it was to ampicillin, cefotaxime, and piperacillin. Salmonella isolates had a very high mean resistance to all the disks used. Conclusion: The results of this study indicated that lack of attention to important points in the use and storage of egg can lead to the transmission of pathogenic bacteria. Also, due to the high antibiotic resistance of isolated bacteria, excessive and unconscious use of antibiotics in chickens' diet, which increases antibiotic resistance, must be prevented.