In vitro influence of photodynamic antimicrobial chemotherapy on staphylococcus aureus by using phenothiazines derivatives associated with laser/LED Light Susana C. P. S. de Oliveira a,b , Juliana S. C. Monteiro a,b,e , , Gustavo M. Pires-Santos c ,Fernando J. P. Sampaio a,b , Rafael Araújo Gomes Júnior c , Maria F. M. Gesteira a,b , Aldo Brugnera a,b,d Fátima A. A. Zanin a,b,d , Marcos A. Vannier-Santos c e Antônio L. B. Pinheiro* a,b,d a Center of Biophotonic, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil, 40110-150; b National Institute of Optics and Photonics, São Carlos, SP, Brazil, 13560-970 c Laboratory of Parasite Biology, Centro de Pesquisas Gonçalo Muniz, Fundação Oswaldo Cruz FIOCRUZ, Salvador, BA, INCT-INPeTAM, Brazil. d Brugnera & Zanin Institute, São Paulo, SP, Brazil 01434-000 e Department of Biology, Estate University of Feira de Santana, Feira de Santana, BA, Brazil, 44036-900. ABSTRACT The aim of this study was to evaluate the effect of photodynamic antimicrobial chemotherapy (PACT) using phenothiazinium dyes - PTZ irradiated with red laser (ʎ660nm) or red-orange LED (ʎ632±2nm) on Staphylococcus aureus in vitro. triplicate tests were performed in 10 groups: control, Laser (L1 + P - and L2 + P - ) bacterial suspensions were irradiated only with laser energy 2.4 and 4.8 J/cm 2 respectively, (Led1 + P - and Led2 + P - ) irradiated only with LED energy 2.4 and 4.8 J/cm 2 respectively, (L1 + P + and L2 + P + ) irradiated with laser in the presence of 1μg/ml of photosensitizer, (Led1 + P + and Led2 + P + ) irradiated with LED in the presence of 1μg/ml of photosensitizer and finally (L - P + ) only in the presence of PTZ dye. Bactericidal effect of the PACT was assessed by counting colony-forming units. The results showed no significant difference on regards different energy densities on group PACT for both lights. PACT groups (L2 + P + and Led2 + P + ) compared to the Control showed significant reduction of CFUs. LED/Laser groups (L2 + P - and Led2 + P - ) compared to control and PTZ groups showed also significant differences as groups LED/Laser (4.8J/cm 2 ) increased the average of CFUs. Although the results of this study have shown a reduction in average number of colony- forming units by the appropriate Laser or LED-dye treatment combination, it this topic requires further investigation. Keywords: Photodynamic antimicrobial chemotherapy; Staphylococcus aureus; Light emitting-diodes. 1. INTRODUCTION In the last decades the total worldwide rise in antibiotic resistance has driven research to the development of new anti-microbial strategies. Much is already known about the photodynamic inactivation of microorganisms: both antibiotic-sensitive and resistant strains can be successfully photoinactivated and there is the additional advantage that repeated photosensitization of bacterial cells does not induce a selection of resistant strains 1,2 . In particular, staphylococcal resistance to methicillin and closely related penicillin was noted since the introduction of penicillinase-stable β-lactam antibiotics like methicillin or cloxacillin 3 . The formation of a biofilm, observed in Staphylococcus strains, increases their resistance to antibiotics and protects the cells against the action of the immune system 4 . • albp@ufba.br; phone 55 71 3283-9010; fax 55 71 3283-9010; www.laser.odontologia.ufba.br Mechanisms for Low-Light Therapy IX, edited by Michael R. Hamblin, James D. Carroll, Praveen Arany, Proc. of SPIE Vol. 8932, 89320H · © 2014 SPIE · CCC code: 1605-7422/14/$18 · doi: 10.1117/12.2038576 Proc. of SPIE Vol. 8932 89320H-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/06/2014 Terms of Use: http://spiedl.org/terms