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

Abstract 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.