Potassium selenocyanate potentiates both antimicrobial blue light and antimicrobial photodynamic inactivation against Gram-negative bacteria

This study investigated the potentiation of KSeCN for both antimicrobial blue light (aBL,405nm) and antimicrobial photodynamic inactivation (aPDI) against different species of Gram-negative bacteria. For planktonic (108CFU/ml) E.coli, with KSeCN treatment (50mM concentration and 60J/cm2 aBL) demonstrated an increase of 4- to 5-log10 CFU reduction compared to aBL alone. E. coli, with KSeCN treatment (50mM,100uM Verteporfin and 20J/cm2 aBL) demonstrated an increase of 4- to 6-log10 CFU reduction compared to aPDI (100uM concentration of Verteporfin and 20J/cm2 aBL, 30min incubation time) alone. K. Pneumoniae and A. Baumannii show similar results. For biofilm (106 CFU/mL), an obvious CFU reduction of 5- to 7-log10 could be seen with KSeCN treatment (50mM and 100J/cm2 aBL) compared to aBL alone. CFU reduction of 6.5- to 8-log10 could be seen with KSeCN treatment (50mM,100uM Verteporfin and 40J/cm2 aBL) compared to aPDI alone (100uM concentration of Verteporfin and 40J/cm2). Confocal results (live/dead) made these findings solid which highlight the KSeCN function to potentiate aBL and aPDI against G-bacteria, offering a novel approach for antibiotic resistance infections.