LAUSR

ABSTRACT 1. The objective of this study was the isolation and morphological characterization of temperate bacteriophages induced from Staphylococcus aureus strains isolated from clinical samples from broiler chickens and turkeys. 2. Eighty-five S. aureus strains were tested for susceptibility to oxacillin in order to determine which were methicillin resistant (MRSA). A total of 24 strains showed resistance to methicillin. 3. Thirty-one bacteriophages that were lytic against S. aureus strains were isolated and the host range of the bacteriophages was evaluated. Based on the presence of a specific nucleotide sequence, molecular identification of bacteriophages was performed and the presence of genes responsible for the production of classical enterotoxins (A-E) was also analysed. 4. All the isolated bacteriophages had an icosahedral head and a long, thin, non-contractile flexible tail, characteristic of the family Siphoviridae of the order Caudovirales. Based on multiplex PCR results, the phages were found to belong to serogroups A, B and F (Fa, Fb subgroup), which include mostly temperate phages infecting S. aureus. 5. The titre of the phages ranged from 10–4 to 10–9 PFU/ml. The bacteriophages exhibited strong lytic properties against some of the strains of Staphylococcus. The broadest spectrum of activity against the strains was observed in the case of phages sa2, sa3, sa6, sa12, sa15 and sa21. 6. The PCR results showed that of the 31 bacteriophage DNA samples, 4 (12.9%) appeared to have enterotoxigenic genes.