Avaliação da atividade antimicrobiana da terapia fotodinâmica no tratamento da microbiota bucal

Abstract

Photodynamic Therapy (PDT) is based on the interaction of light with a photosensitizer capable of promoting microbial destruction. In the present work, the antimicrobial activity of aPDT was evaluated in vitro using two photosensitizers (phenothiazine and annatto) and different times of treatment of oral biofilm, as well as microorganisms were identified and bacterial resistance and sensitivity to certain antibiotics were evaluated. For this, antimicrobial samples of oral biofilm (tongue) were collected from patients without and with pneumonia admitted to the ICU, who were intubated for a period of at least 24 and at most 48 hours, using swabs soaked in saline solution (NaCl 0.5 %) and later cultivated in agarized media. Samples from patients without pneumonia were randomized into: non-pneumonia control group (NP - C): microorganisms without intervention; non-pneumonia chlorhexidine group (NP - CLX): used 0.12% chlorhexidine; non-pneumonia group red PDT (NP - PDTV): used aPDT using 630 nm LED and phenothiazine photosensitizer; non-pneumonia blue PDT group (NP - PDTA): used the use of aPDT using 450 nm LED and annatto photosensitizer, both using a single application. And control pneumonia group (P - C): microorganisms without intervention; group with chlorhexidine pneumonia (P ¬ CLX): used 0.12% chlorhexidine; group with red PDT pneumonia (P - PDTV): used the use of PDT using 630 nm LED and phenothiazine photosensitizer; group with blue PDT pneumonia (P - PDTA): used the use of PDT using 450 nm LED and annatto photosensitizer. They were irradiated with the following parameters: red LED (λ630 ± 10ηm) or blue LED (λ450 ± 10ηm), both at 100 mW power and treated for 150, 300 or 600 seconds. After 24 hours, colony forming units (CFU) and antibiogram were counted. The results showed that the NP – CLX and P – CLX groups promoted total CFU reduction. The PDT groups in oral biofilm without and with pneumonia showed that the CFU reduction was dependent on the treatment time, being better at 600 seconds of treatment. Through the genetic code, Gram-negative microorganisms such as Pseudomonas aeruginosa and Gram-positive microorganisms such as Bhargavaea sp., Desemzia incerta, Kocuria rosea, Micrococcus sp. ,Micrococcus luteus, Agrococcus carbonis, Microbacterium paraoxydans, Corynebacterium sp., Dietzia aurantiaca, Enterococcus faecalis and Staphylococcus saprophyticus.The antibiogram performed evaluated the multiple antimicrobial resistance index (IRMA) characterizing multiresistance to all. Conclusion: Despite being composed of multidrug-resistant microorganisms, aPDT showed potential for the treatment of oral biofilm in patients with and without pneumonia.