Blue 470   nm light suppresses the growth of @entity11621 and methicillin-resistant @entity794 ( XXXX ) in vitro.

@entity2491 @entity11621 @entity794
BACKGROUND AND OBJECTIVE: Emerging evidence suggests that blue light can photo-inactivate some bacteria of clinical importance. Consequently, we tested the hypothesis that 470   nm light can suppress growth of two recalcitrant bacteria, @entity794 and @entity2491 . MATERIALS AND METHODS: We plated 5   *   10(6) and 7   *   10(6) CFU/ml USA300 strain of @entity794 and 1   *   10(6) CFU/ml of @entity11621 serovars Typhimurium and Heidelberg. Plates were irradiated with 55, 110, 165 and 220   J/cm(2) of blue light, incubated at 37  C for 24 hours and colony counts determined. RESULTS: Compared with controls, blue light irradiation produced a significant dose-dependent reduction in the number of colonies formed by each bacterial strain (P   <   0.001). Irradiation of 5   *   10(6) and 7   *   10(6) CFU/ml @entity794 with 55   J/cm(2) produced 92% (4.6   *   10(6) CFU/ml) and 86% (6   *   10(6) CFU/ml) inactivation respectively, while 110 and 220   J/cm(2) suppressed each @entity794 density 100%. Irradiation of @entity2491 with 55 and 110   J/cm(2) suppressed bacterial growth 31% (3.1   *   10(5) CFU/ml) and 93% (9.3   *   10(5) CFU/ml) respectively; while @entity2491 Heidelberg was inhibited 11% (1.1   *   10(5) CFU/ml) and 84% (8.4   *   10(5) CFU/ml) respectively by the two fluences. Complete inactivation of each @entity2491 strain was achieved using 165 or 220   J/cm(2) . CONCLUSION: The observed inhibition of Gram-positive ( @entity794 ) and Gram-negative ( @entity2491 ) bacteria suggests the versatility of blue light in bacteria eradication, making it a viable intervention strategy for decontamination of food and environments that harbor such bacteria. Lasers Surg. Med.    2015 Wiley Periodicals, Inc.
