Investigation of contamination to Salmonella and Staphylococcus aureus in native and industrial hen’s eggs in Qhom areas

AbstractAmong foods with animal origin, the egg always has the potential ability to transfer foodborne pathogens which may cause diseases in human. In food industries, eggs is used for different purposes such as production of mayonnaise, spices foods, ice creams and other food products which could be consumed directly without any heating, cooking or half cooking. Salmonella is one of the most common causes of enteritis and food poisoning worldwide. Staphylococcus aureus is one of the three major causes of food borne illnesses around the world and a popular cause of food poisoning in public. The present investigation was performed to determine the probably transferring Salmonella and Staphylococcus aureus to consumers by hen’s eggs. In this research, totally 120 (60 native and 60 industrial) eggs were collected from different part of Qhom areas. The eggs immediately were transferred to microbiology laboratory in the aseptic condition. In order to determine Salmonella, after culturing the internal content of eggs (albumin and yolk) according to the reference conventional methods, the suspected colonies were inoculated in TSI, Urea and LD agar. Then the differential and serological tests were carried out and the Salmonella positive eggs were distinguished. Also about Staphylococcus aureus, after enriching the content of eggs (albumin and yolk) in 10% salt cooked meat medium at 37˚C for 24 hours and inoculation on Baird Parker agar, incubated at 37˚C for 48 hours. Then the suspected colonies were selected and the tube coagulase test was carried out on them. The results showed that one sample of 60 laying eggs (1/66%) was contaminated to salmonella enteritidis, but there was no any contamination in industrial eggs, while 24 (40%) samples of 60 native eggs were contaminated to coagulase positive Staphylococcus aureus, but there were only 2 (3/3%) samples contamination in industrial eggs, therefore according to the obtained results, the consumption of native hen’s eggs could be a threat for public health especially in raw consumption in some foods like mayonnaise, desserts etc. So more seriously monitoring of native egg producers should be considered by responsible authorities.