Isolation of Salmonella resistant to hypochlorous acid from a poultry abattoir.

Salmonella is a Gram-negative bacterium that has been implicated in several food-borne poisoning outbreaks. Poultry products are considered to be the major vehicles of food-borne poisoning caused by Salmonella. The resistance of Salmonella, isolated from different stages in a local poultry abattoir, to hypochlorous acid (HOCl) was studied. Isolates cultured in quarter strength Tryptone Soya Broth were treated with 72 ppm HOCl, incubated at 30 degrees C with shaking, and absorbance was measured at 660 nm every 20 min. A number of resistant isolates, which carried on growing following HOCl addition, were obtained. All the isolates from the bleeding stage were sensitive to HOCl, whereas those from the scalding stage were resistant to HOCl. Other stages had a population of resistant and sensitive isolates. It is evident that some Salmonella will grow in the presence of concentrations of HOCl deemed to be inhibitory. Hence, an effective concentration of HOCl must be applied in poultry abattoirs to ensure that all the Salmonella are eradicated.