Antibiotic Resistance Among Staphylococcus aureus and Escherichia coli Isolated From Traditional and Industrial Food Samples

Foodborne diseases are one of the serious problems in the world. Every year, more than 100 million people are affected by foodborne and waterborne diseases particularly immunocompromised diseases.
The aim of the present study was to evaluate bacterial load and antibiotic resistance pattern in bacterial isolates from food samples of meat, dairy, and pastry products from west of Tehran, Iran, during April 2007 to March 2008.
A total of 1625 different food samples including dairy products, meat and pastries were collected randomly from different parts of the west of Tehran. All samples were kept at 4°C. The samples were first cultured according to the standard bacteriological methods and then Staphylococcus aureus and Escherichia coli isolates were identified using standard bacteriological tests. Antimicrobial susceptibility test was performed by disk diffusion method according to Clinical & Laboratory Standards Institute (CLSI) guidelines.
During 2007 and 2008, 2.8% and 3% of the food samples were contaminated with S. aureus. Similarly, 3.5% and 6.4% of the food samples were contaminated with E. coli. E. coli isolates were highly resistant to amikacin and cephotaxime and this resistance was increased in 2008. Similarly S. aureus isolates were resistant to ciprofloxacin, cephotaxime, gentamicin, and tetracyclin. There was no significant difference during 2007-2008.
The rate of contamination during 2007 was 2.8% and during 2008 was 3% for S. aureus. This strain was isolated from the food samples.
Further studies should be done to determine the changes of bacterial resistance pattern for various food samples. Thus, the baseline for comparison with future prospective studies should be established, enabling the determination of trends over time.