Aerobic bacteria isolated from eggs and day-old chicks and their antibacterial resistance in Shiraz, Iran

Document Type : Full paper (Original article)


1 Department of Food Hygiene and Public Health, School of Veterinary Medicine, University of Shiraz, Shiraz, Iran

2 Department of Avian Medicine, School of Veterinary Medicine, University of Shiraz, Shiraz, Iran

3 Food and Drug Control Laboratories, Ministry of Health and Medical Education, Tehran, Iran


To study the putative transfer of antibiotic resistance from broiler breeders to human, hen’s eggs and their
day-old chicks were examined for the presence of bacteria. The most frequently isolated organisms in
decreasing order were: Streptococcus spp., Bacillus spp., Staphylococcus spp., Klebsiella spp., Enterobacter
spp. and Escherichia coli followed by Citrobacter spp., Proteus spp. and Pseudomonas spp. from the eggs and E. coli, Enterobacter spp. and Citrobacter spp. followed by Klebsiella spp. and Bacillus spp. from the chicks. Different detection methods were evaluated which use various enrichment and plating media for bacteria in eggs and day-old chicks. Sensitivity tests showed the presence of antibacterial resistant strains of bacteria. In comparison, resistance to all antibiotics in chicks’ isolated bacteria were more frequent than eggs’ isolates, but statistically no significant differences between patterns of antibacterial resistance were seen (P ≤ 0.05). Twenty-three, 54, 55, 60, 24 and 10% of chicks’ isolates were resistant to chloramphenicol, enrofloxacin, erythromycin, furazolidone, trimethoprim and tylosin, respectively. Whereas these data about eggs’ isolates were as follows: 1, 12, 18, 18, 10 and 6%, respectively. This study revealed that eggs are often contaminated with different bacteria and could be potential vehicles for transmitting of these bacteria through their broilers. Our findings stress the need for increased implementation of hazard analysis of critical control points (HACCP) and consumer food safety education efforts.