Abstract
Due to the overuse of antibiotics in medicine and food production, and their targeted mechanism of action, an increasing rate in spreading of antibiotic resistance genes has been noticed. This results in inefficient therapy outcomes and higher mortality all over the world. Pseudomonas aeruginosa (carbapenem-resistant) is considered one of the top three critical species according to the World Health Organization’s priority pathogens list. This means that new drugs and/or treatments are needed to tackle infections caused by this bacterium. In this context search for new/alternative approaches that would overcome resistance to classical antimicrobials is of prime importance. The use of antimicrobial photodynamic inactivation (aPDI) and antimicrobial peptides (AMPs) is an efficient strategy to treat localized infections caused by multidrug-resistant P. aeruginosa. In this study, we have treated P. aeruginosa cells photodynamically in the presence and in the absence of AMP (CAMEL or pexiganan). The conditions for aPDI were as follows: rose bengal (RB) as a photosensitizing agent at 1–10 μM concentration, and subsequent irradiation with 514 nm-LED at 23 mW/cm2 irradiance. The analysis of cell number after the treatment has shown that the combined action of RB-mediated aPDI and cationic AMPs reduced the number of viable cells below the limit of detection (<1log10 CFU/ml). This was in contrast to no reduction or partial reduction after aPDI or AMP applied separately. Students t-test was applied to test the statistical significance of the results. Noteworthy, our treatment proved to be effective against all 35 clinical isolates of P. aeruginosa tested within this study, including those characterized as multiresistant. Moreover, we demonstrated that such treatment is safe and does not violate the growth dynamics of human keratinocytes (77.3–97.64% survival depending on the concentration of the studied compounds or their mixtures).
Highlights
Since the discovery of penicillin in 1929, followed by a great success in the control of bacterial infections, a golden era of antibiotics has begun
We examined the combined action of rose-bengal-based antimicrobial photodynamic inactivation (aPDI) and two antimicrobial peptides (AMPs), namely pexiganan and CAMEL, showing significantly enhanced effect of the studied combination
We showed in our study that inactivation of the Gramnegative bacterium is efficient and can be exploited as potential antimicrobial therapy for treatment of local infections caused by multiresistant P. aeruginosa
Summary
Since the discovery of penicillin in 1929, followed by a great success in the control of bacterial infections, a golden era of antibiotics has begun. Pseudomonas aeruginosa is a chief opportunistic pathogen that can cause nosocomial infections in susceptible persons in medical institutions This bacterium can spread via human-tohuman direct distribution, and via water systems (up to 50%) in hospital wards (Blanc et al, 2004). P. aeruginosa is responsible for the complicated infections, in people with compromised immunity, e.g., oncological patients, people after transplantation, elderly people, that are frequently hospitalized This bacterium causes skin and soft tissue infections, which can be fatal for people with burns and after surgeries. The most dangerous population among P. aeruginosa isolates constitute those producing metallo-β-lactamases, conferring resistance to all penicillins, cephalosporins, and carbapenems The latter has been known as the last resort drugs in the treatment of Gram-negative infections (Potron et al, 2015). Being in-line with this trend, photodynamic inactivation of multiresistant pathogens has emerged as a promising alternative to antibiotics
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