Abstract

Phage typing is currently used for typing of Staphylococcus aureus strains beyond the species level in epidemiological studies. A total of 168 Staphylococcus aureus isolates from chicken meat and chicken by-products were phage-typed using the international bacteriophage set for typing Staphylococcus aureus of human origin. One hundred and forty-eight (88.09%) strains were phage-typeable (at least one phage produced 20 or more plaques of lysis). Lysis by phages of group III was the most frequent with 99 (58.93%) sensitive strains. This fact coincides with results of other authors. Twenty-nine different phage patterns were observed and three (95, 75/84 and 6/1030/W57) were most common. One hundred and thirty-two (89.19% of typeable strains) showed these or indistinguishable (only one phage reaction difference) patterns. Twenty-six out of seventy chicken samples (37.14%) harboured more than one phage type of Staphylococcus aureus. This fact emphasizes the convenience of subtyping several Staphylococcus aureus isolates from the same sample in epidemiological studies. 80% of sausages and hamburgers contained the same Staphylococcus aureus phage types, which were not found in any of the other food types. This fact suggests a cross contamination during the processing of these foods. Phages 6, 75, 84, 1030 and W57 showed the greatest activity. None of the Staphylococcus aureus strains were sensitive to phages 47, 81 and 94.

• Keywords: Staphylococcus aureus; typing; phage typing; poultry; Spain