Abstract: Objective: To investigate the prevalence and toxin genes profile of Staphylococcus aureus in infant milk powder and infant rice cereal marketed in Shaanxi province, China. Methods: Totally 367 various samples from 18 regions in Shaanxi province were tested by the national standard method to isolate Staphylococcus aureus; the nuc genes were examined to confirm Staphylococcus aureus status; Staphylococcus aureus enterotoxin genes, exfoliative toxins genes, toxic-shock syndrome toxin-1 gene and Panton-Valentine Leukocidin gene were detected by PCR. Results: Of 367 samples examined, 30 were positive for Staphylococcus aureus, result in a positive rate of 8.17% (30/367), including 11.19% (16/143) milk powder samples and 6.25% (14/224) rice cereal samples. From these positive samples, 29 and 25 strains were isolated from milk powder and rice cereal samples respectively. Among all identified Staphylococcus aureus isolates, 34 strains harbored at least one of the tested toxin genes. The toxins gene profiles detected in S. aureus from infant milk powder samples were pvl, sea, seb, sec, sed, seg, seb＋seg, sec＋seg and seb＋sed＋seg, and their positive rates were 44.82% (13/29), 10.34% (3/29), 13.79% (4/29), 17.24% (5/29), 6.89% (2/29), 41.38% (12/29), 10.34% (3/29), 10.34%(3/29) and 3.45% (1/29) respectively; The toxin gene profiles in S. aureus from infant rice cereal samples were pvl, sea, sec, sed, see, seg, sea＋seg, sec＋seg and sec＋see＋seg, and the positive rates were 36% (9/25), 4% (1/25), 20% (5/25), 4% (1/25), 12% (3/25), 36% (9/25), 4%(1/25), 16% (4/25) and 8% (2/25), respectively. Neither ets,tsst-1, seh, sei nor sej genes were detected in infant milk powder or infant rice cereal. Conclusion: Infant milk powder and infant rice cereal in Shaanxi province were contaminated with S. aureus, some of which contained various toxin genes. The existence of the pathogen in these food products may constitute a potential risk for infants, health.

Key words: infant milk powder, infant rice cereal, Staphylococcus aureus, toxins genes