Photodynamic inactivation (effect of laser with and without photosensitizer) on viability of streptococcus pyogenes

Abstract

Abstract:
 Burns wounds infection is the high most frequent complications of burns as a result of penetration of bacteria from neighboring tissue. Because of expanded utilization of antibiotics, the spread of multi-drug resistance bacteria emerge as one of alarming hazard to public health.
 Photodynamic inactivation is the technique that can be used to prohibit these organisms. This study focused on bactericidal potency of toluidine blue (TBO) photosensitizer and red laser radiation of 635nm with different doses against multi-drug resistant streptococcus pyogenes (S. pyogenes) isolated from infected burns wounds to see if it is susceptible to photodynamic inactivation .
 A total of 45 isolates were collected from 38 patients with infected burns wounds samples were collected from September to December 2019.Burns wounds swabs were employed using standard procedure of swab collection. Among these, eleven isolates were multidrug resistant S.pyogenes. More resistant isolate that has been proved to all antibiotics used. This multidrug resistant isolate used in all experiments. Bacterial suspension was diluted by using serial dilution. The suspension of S. pyogenes in normal saline was treated with red laser radiation at a wavelength 635nm with and without TBO, and investigated the effect of changing laser doses (3.6 ,7 and 10.8 J/cm2) corresponding to laser exposure time (5,10 and 15 minutes and different photosensitizer concentrations on viability of S. pyogenes isolated from infected burns wounds. The results of this study suggest that multi- drug resistance S pyogenes isolated from infected burns wounds inhibited by using photodynamic inactivation mediated by TBO and red laser at a wavelength 635 nm. The effective technique for killing or inhibiting S. pyogenes isolated from infected burns wounds is the combination of red laser at a wave length 635nm and TBO. Combination of TBO and red laser light prohibit S. pyogenes, the optimum results of bacterial inhibition obtained at 50µg/ml, and laser dose 7 J/cm2 corresponding to exposure time 10 minutes.