Photodynamic Inactivation Of Staphyloccus Aureus Biofilms By Carboxypterin

A. G. MIÑAN; C. LORENTE; A. H. THOMAS; M. A. FERNÁNDEZ LORENZO DE MELE; P. L. SCHILARDI

Congreso; 16th International Congress on Photobiology; 2014

Staphylococcus aureus is a major cause nosocomial infection of surgical wounds and infections associated with indwelling medical devices [1]. Unfortunately, emerging multiresistant S. aureus strains produce many therapeutic complications; for this reason, is of vital importance the development of novel strategies for the treatment of infections. Photodynamic inactivation (PDI) of bacteria has recently emerged as a promising and innovative approach for the erradication of pathogenic microorganisms [2]. The aim of this study was to evaluate the antibacterial photodinamic properties of carboxipterin (CPT) against S. aureus biofilms, since it is well known that biofilms are highly tolerant to antimicrobial agents. Planktonic and sessile bacteria were challenged with CPT (0,1 - 200 M) and UV-A radiation for 2 h at 28 ºC. In vitro results showed that CPT exhibited antimicrobial activity on planktonic and sessile bacteria of S. aureus. The MBC (minimal bacterial concentration) of CPT was 0.1 M for irradiated planktonics cells, and the bacterial viability was reduced at least 5 log10 units compared with the initial inoculums. Biofilms of S. aureus were grown? on microtiters plates. After PDI treatment, the number of viable sessile cells deacreased 3 log10 unit at 50 M of CPT. . The comparison of the MBC values for planktonic and sessile cells shows that sessile bacteria exhibited an increased resistance to PDI (near 500-fold. However, CPT at low concentration (50 M) has bactericidal activity on S. aureus biofilms. These results encourage further investigation on the potential use of PDI based on CPT for the treatment of localized infections.