Molecular detection and genetic relatedness of enteric bacteria from Iraqi dairy products

Raw milk and unpasteurized dairy products are still widely consumed in Iraq, particularly in rural areas. These products may carry harmful bacteria, including those resistant to antibiotics. Although many studies have focused on common pathogens, few have used molecular methods to detect and compare local bacterial strains with international strains. This lack of data creates a gap in understanding the public health risk and genetic diversity of these bacteria in Iraqi dairy products.

This study aimed to detect bacteria in local dairy products from Al-Diwaniyah City, Iraq.

This study was observational. Milk, yogurt, and cheese samples were taken. A total of 150 samples were collected: 60 milk, 45 yogurts, and 45 cheese samples. They were collected from farms, markets, and shops. Each sample was tested in the laboratory. The objectives of this study were to detect and identify the presence of bacteria in local dairy products, including milk, yogurt, and cheese, collected from Al-Diwaniyah City, Iraq. This study aimed to use both biochemical methods, such as the VITEK^®2 system, and molecular tools, such as polymerase chain reaction and 16S rRNA sequencing, to accurately classify the bacterial species. Another goal was to compare the genetic sequences of local isolates with those of international strains using Basic Local Alignment Search Tool analysis and phylogenetic tree construction. In addition, we evaluated the protein patterns of the bacterial isolates using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to understand their enzymatic activity. These objectives were designed to highlight the risks of contamination in unpasteurized dairy products and support better food safety practices using molecular evidence.

Klebsiella pneumoniae, Klebsiella aerogenes, Enterobacter cloacae, Escherichia coli, and Enterococcus cecorum were found. These bacteria were very similar to those from other countries, such as India and Egypt. Gene sequences were matched with those in the GenBank database. Some gene regions were the same in all bacteria. Other regions exhibited changes. SDS-PAGE showed clear protein bands between 20 and 70 kDa, confirming diverse peptide profiles among the bacterial isolates. These changes help to separate the bacterial species.

Dairy products can carry serious bacteria. These bacteria can be studied by examining their genes. Regular checking of food is needed. Molecular tools can help identify and track these bacteria.