Molecular characterization of some food borne pathogens in soft cheese samples collected from Jeddah, Saudi Arabia

Abstract

The growing industrial attention toward rapid methods and the wide use of nucleic acid amplification techniques has led for developing and applying of PCR based methods for food-borne pathogens recognition. In the current study, 20 cheese samples, collected from a local supermarket of Jeddah, Saudi Arabia were examined for the presence of metals and some pathogenic bacteria. Cheese content of Na + and K + were found to be higher in fresh cheese than other elements. Cr 2+ , Ni 2+ , Zn 2+ and Al 3+ were detected at low concentrations in cheese. Additionally a multiplex PCR method was developed for detection of Salmonella spp., Listeria monocytogenes and Escherichia coli O157:H7 as the most common cheese borne pathogens. Bacterial enrichment was carried out and bacterial genomic DNA was extracted. A set of primers was designed based on specific genes for Salmonella spp. (invA), L. monocytogenes (prfA) and E. coli O157:H7(eaeA). Additionally, a universal –multiplex PCR based on the highly conserved sequences published on genbank database for the previous genes was used for detecting the previous cheese borne pathogenic bacteria. Three (15 %) out of 20 cheese samples, were contaminated with pathogenic bacteria. Finally, the used method is a promised method, simple, rapid and efficient for detecting pathogenic bacteria in contaminating cheese.