The prevalence of some pathogenic bacteria in traditional cheese sold in local markets in Sulaimani, Iraq

• Zhwar Abdullah Mohammed1, Khulod Ibraheem Hassan2

  Author

Cheese is an important dairy product that is widely consumed worldwide. However, it can become contaminated with foodborne pathogens during production, processing, handling, or storage, posing a potential risk to public health. The aim of the present current study was to investigate the occurrence of major foodborne pathogens, including Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp., in some cheese samples sold in Sulaimaia city of Iraq. To achieve this, sixty-three cheese samples were collected from retail markets and analyzed using conventional culture methods. The results confirmed using  biochemical tests (VITEK 2), and Molecular based method using  polymerase chain reaction (PCR)targeting species specific primers targeting hlyA ,16S rRNA genes in Listeria monocytogenes  , Nuclease genes ,16S rRNA genes in staphylococcus aureus and invA , hilA(SPI-1) gene in salmonella spp. .The results showed that Staphylococcus aureus had the highest prevalence (42.85%) among the tested pathogens in cheese samples, followed by Listeria monocytogenes (4.8%)), while Salmonella spp. showed the lowest prevalence (3.17%). Identification of S. aureus using VITEK 2 AST-GP79 card was successfully done with a good to acceptable level of confidence (90 – 99%), and for L. monocytogenes the rate of probability of identification was 97% , and for Salmonella was 98%. Identification of the studied bacteria and assessment of their virulence potential was successfully confirmed by PCR analysis .S. aureus isolates were identified by the amplification of 16S rRNAgene (750 bp) and nuc gene (276bp). L. monocytogenes, were identified by the amplification of 16S rRNA gene (938bp) and hlyA genes (701bp). PCR assay also confirmed the presence of Salmonella spp. by amplification of the invA  (275bp) and hilA gene(768bp).All these techniques provided a reliable and complementary approach for the identification of bacterial pathogens in the studied cheese samples. The present results indicated that traditional cheeses manufactured in Sulaimani were not safe microbiologically. Regular bacterial detection of food born bacteria in cheese is needed by combining culturing method with more accurate rapid molecular detection technique.

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