Photodynamic inactivation of klebsiella pneumoniae and Escherichia coli bacteria using two symmetrical substituted zinc (II) phthalocyanines

CLEMENTI, R; MIRETTI, M; BAUMGARTNER, M. T; TEMPESTI, T. C

CORDOBA

Congreso; XI Congreso Argentino de Microbiología General-SAMIGE; 2015

Photodynamic inactivation of Klebsiella pneumoniae and E.coli bacteria using two symmetrical substituted zinc (II) phthalocyaninesRomina Clementi,b Mariana Mirettia, María T. Baumgartnera and Tomas C. Tempestia a INFIQC (CONICET). Dpto. Quimica Orgánica,, FCQ - UNC, Ciudad Universitaria, Córdoba, Argentina.b Departamento de microbiología, Hospital Policlínico Policial, Córdoba (5000), Córdoba, Argentina. The widespread occurrence of antibiotic-resistant microorganisms has necessitated considerable need for new antimicrobial modality treatment. Photodynamic therapy (PDT) as a method utilizes visible or ultraviolet light in combination with a photosensitizing agent to induce several phototoxic reactions, which results in cell damage or death. Photodynamic reaction involves a light absorption by a photosensitizer to excite the molecule to the excited singlet state. This excited state undergoes intersystem crossing to the long-lived triplet state, which can react with molecular oxygen inducing reactive species such as singlet oxygen, superoxide, and radicals. These reactive species can oxidize the surrounding bioorganic molecules leading to cell death.Phthalocyanines, which are characterized with far red wavelength absorption (>670 nm), long triplet life time (~1 ms), and high quantum yields of singlet oxygen generation (>0.2), have been studied as drugs in microbial photodynamic inactivation.The positively charged phthalocyanines can effectively photoinactivate both, gram-positive and gram-negative bacteria. The gram-positive are more susceptible to photoinactivation than gramnegative due to the morphology characteristics of their membranes.Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria are an emerging group of highly drug-resistant bacteria causing infections associated with significant morbidity and mortality.The photodynamic activity of two new cationic phthalocyanines (TMZnPc and TMAZnPc) and commercial ZnPc, was evaluated in KPC-producing bacteria and E. coli ATCC 25922 bacteria. Both KPC-producing as E. coli ATCC 25922 were incubated with photosensitizers for 30 minutes in the dark at 37 °C. The photoinactivation of the microorganism was determinated for different irradiation times (10, 15 and 30 minutes).