A survey of prevalence and antibiotic resistance pattern of Staphylococcus aureus strains isolated from eggs in Ardabil area, Iran

Staphylococcus aureus is one of the main causes of foodborne diseases globally. Eggs can contaminated with S.aureus when they make contact with dirty surfaces, litter materials as well as clothing and hands of poultry workers. Therefore, the purpose of this study was to determine the prevalence and antibiotic resistance of S. aureus strains isolated from eggs in Ardabil area located in the northwest of Iran. One hundred and fifty eggs were collected randomly from poultry farms (n=50) and retail outlets (n=50 native and n=50 bulk) in different parts of Ardabil. In terms of S. aureus contamination, eggs were examined using bacterial culture and biochemical tests. From 150 egg samples examined, 9 samples (9.3%) were infected with S. aureus. Out of these, the highest contamination rate of S. aureus was observed in native, industrial and bulk eggs 50%, 28.58% and 21.42%, respectively. There was the highest resistance to penicillin (78.57%), tetracycline (71.42%) and ampicillin (64.28%), while the lowest resistance was observed to chloramphenicol (21.42%), gentamicin (14.28%) and ciprofloxacin (7.14%). All the S. aureus isolates were susceptible to vancomycin (100%). The results of this study indicate the presence of S. aureus infection in eggs and the relatively high prevalence of S. aureus isolates  resistant to some antibiotics is a potential risk to human health. It is necessary to pay attention to hygienic points in storing and consuming eggs and monitoring the use of antibiotics.