Bacterial isolates exhibiting multidrug resistance, hemolytic activity, and high 16S rRNA gene similarity with well-known pathogens found in camel milk samples of Riyadh region.

Customary consumption of unpasteurized milk by the population in the central Najed region of Saudi Arabia may pose a health risk. Therefore, 80 camel milk samples were collected aseptically from seven different stations of Riyadh region. The biochemical and microbiological properties of these milk samples were determined. Nutrient agar and brain heart infusion agar were used to determine mesophilic aerobic counts (MACs). The MAC in each mL of milk varied from 60 to 16 × 104  CFU/mL on nutrient agar. Based on the colony morphology, 176 colonies were collected from different samples, and these isolates were de-replicated into 80 unique isolates using rep-PCR analysis. Surprisingly, the 16S rRNA sequence analysis of these strains revealed that more than one-third of the collected milk samples contained strains that share maximum sequence similarities with well-known pathogens, such as Brucella, Bacillus anthracis, Listeria monocytogenes, and MRSA. Furthermore, many strains exhibit 16S rRNA gene similarity with opportunistic pathogens such as Citrobacter freundii and Kytococcus schroeteri. Many strains exhibit β-hemolytic activity and resistant to six different antibiotics. Our study suggested that consumption of raw camel milk from this region constitutes a great health risk.