Molecular characterisation, genotyping and survival of Aeromonas hydrophila isolated from milk, dairy products and humans in Egypt

Two Aeromonas species, Aeromonas hydrophila and Aeromonas sobria, were isolated from raw milk (8% and 5.3% of samples tested, respectively), yoghurt (12% and 8% of samples tested, respectively) and cheese (4% and 2% of samples tested, respectively). Only A. hydrophila was isolated from human stool samples (18.8% of samples tested). Aerolysin and haemolysin associated genes were characterised in 12 and 3 isolates, respectively, while both genes were identified simultaneously in 9 isolates. Genotyping of the isolates by random amplified polymorphic DNA (RAPD) PCR revealed a high discriminatory index (D = 0.966). The storage of yoghurt samples inoculated with A. hydrophila showed the ability of the bacteria to survive for 14 days, resembling the shelf-life of yoghurt at 4 °C and 12 °C. To the best of our knowledge, this is the first study to assess the survival of A. hydrophila in yoghurt at refrigeration temperature.