INVESTIGADORES
CASAS Adriana Gabriela
congresos y reuniones científicas
Título:
Photodynamic inactivation of Staphylococcus aureus employing PSs derived from plants
Autor/es:
GÁNDARA L; MAMONE L; VAINMAN, M.; ROSSETTI MV; DI VENOSA G; CALVO G.; BATLLE A; BUZZOLA F; CASAS, A.
Lugar:
Lucerna
Reunión:
Congreso; International Congress of Porphyrins and Porphyrias; 2013
Resumen:
Proposed clinical fields of interest of
antimicrobial Photodynamic Inactivation (PDI) include the treatment of chronic
ulcers, infected burns, acne vulgaris, cutaneous leshmaniasis, and a variety of
oral infections. PDI has been employed
in eradication of biofilms present in dental plaques, oral implants, prothesis
and infected catheters. On the other hand, PDI employing cationic (PS) are
particularly efficient in the treatment of S.
aureus and S. epidermidis
biofilms.
Among the bacteria, Staphylococcus aureus
is particularly clinically important since
the emergency of resistance to antibiotics leads to the need of new alternative
therapies.
In a screening
study, we have identified several plants with high photoactivity against
bacteria.
The aim of this work
was to evaluate the ability of natural and synthetic PSs to photoinactivate S. aureus (SH100 strain and RN6390
strain, deficient in sigB factor and thus impaired in its ability to produce
the antioxidant pigment Staphyloxanthyne).
The radiation
source was a set of two
tungsten halogen lamps of about 23 mW/cm2. Unirradiated and irradiated cells
were serially diluted with PBS and each dilution was plated on a solid growth
medium.
PDI of S. aureus RN6390 employing Solanum verbascifoliium flower extract (0.5 mg/ml) and Cissus
verticillata root (0.5 mg/ml); induce an impairment of 6 logs decrease of
CFU, Combretum fruticosum leaf (0.5
mg/ml) provoked 1 log decrease, whereas Scutia
buxifolia leaf (0,01mg/ml) induced 2 logs decrease. Suspensions exposed to
Toluidine blue-PDI (synthetic PS) induced 7 logs decrease employing 5 µM.
Mean ± SD were as follows: Control: 1.3x108 ± 8.7x107 CFU/ml vs
Cissus verticillata 0.5 mg/ml:
7.7x102 ± 9.2x102; Solanumverbascifollium 0.5 mg/ml: 1.9 x102 ± 2.1x102; Combretum fruticosum 0.005 mg/ml: 4.3x107
± 5.4 107; Scutia
buxifolia 0.01 mg/ml: 7.7x106 ± 1.0x107 and Toluidine
blue 5 µM: 9.08x101 ± 2.01x102 (p< 0.01, Mann-Whitney test). RN6911 strain was more resistant to PDI employing all the PSs as
compared to RN6390.
The most relevant conclusion is that S. aureus can be photoinactivated
employing both natural and synthetic PSs. We are carrying out studies to
photoinactivate biofilms.