Inactivation of Staphylococcus aureus by pulsed UV-light sterilization

Pulsed UV light is a novel technology to inactivate pathogenic and spoilage microorganisms in a short time. The efficacy of pulsed UV light (5.6 J/cm2 per pulse) for the inactivation of Staphylococcus aureus as suspended or agar seeded cells was investigated. A 12-, 24-, or 48-ml cell suspension in buffer was treated under pulsed UV light for up to 30 s, and 0.1 ml of sample was surface plated on Baird-Parker agar and incubated at 37 degrees C for 24 h to determine log reductions. Also, 0.1 ml of cell suspension in peptone water was surface plated on Baird-Parker agar plates, and the plates were treated under pulsed UV light for up to 30 s. The treated and untreated plates were incubated in the conditions described above. A 7- to 8-log CFU/ml reduction was observed for suspended and agar-seeded cells treated for 5 s or longer. In the case of suspended cells, the sample depth, time, treatment, and interaction were significant (P < 0.05). In the case of agar-seeded cells, the treatment time was significant (P < 0.05). Our results clearly indicate that pulsed UV technology has potential for the inactivation of pathogenic microorganisms.