Bloodstream infections are potentially life-threatening diseases. They can cause serious secondary infections, and may
result in endocarditis, severe sepsis or toxic-shock syndrome. <i>Pseudomonas aeruginosa</i> is an opportunistic pathogen and
one of the most important etiological factors responsible for nosocomial infections, mainly in immuno-compromissed
hosts, characteristic of patients with severe burns. Its multiresistance to antibiotics produces many therapeutic problems,
and for this reason, the development of an alternative method to antibiotic therapy is needed. Photodynamic inactivation
(PDI) may be an effective and alternative therapeutic option to prevent bloodstream infections in patients with severe
burns. In this study we report the use of PDI to prevent bloodstream infections in mice with third-degree burns. Burns
were produced on the back of the animals and they were infected with 10<sup>9</sup> cfu/mL of multi-resistant (MR) <i>P. aeruginosa</i>.
Fifteen animals were divided into 3 groups: control, PDT blue and PDT red. PDT was performed thirty minutes after
bacterial inoculation using 10μM HB:La<sup>+3</sup> and a light-emitting diode (LED) emitting at λ=460nm±20nm and a LED
emitting at λ=645 nm±10nm for 120s. Blood of mice were colected at 7h, 10h, 15h, 18h and 22h pos-infection (p.i.) for
bacterial counting. Control group presented 1×10<sup>4</sup> cfu/mL in bloodstream at 7h p.i. increasing to 1×10<sup>6</sup> at 22h, while
mice PDT-treated did not present any bacteria at 7h; only at 22h p.i. they presented 1×10<sup>4</sup>cfu/mL. These results suggest
that HB:La<sup>+3</sup> associated to blue LED or red LED is effective to delay and diminish MR <i>P.aeruginosa</i> bloodstream
invasion in third-degree-burned mice.
In this work we described the potentiality of the Hypocrellin B (HB) modified with the presence of lanthanum (La<sup>3+</sup>)
ions, in eliminate <i>Candida albicans</i> in suspension. The results showed that the presence of lanthanum ions promotes a
red shift of the HB absorption band and an enhancement in singlet oxygen quantum yield in 32%. Also in this work we
obtained that the best molar ration between HB and La concentrations was 1:2. No photobleaching was observed in our
experimental conditions. Antimicrobial activity was studied exciting <i>C. albicans</i> suspension with a 460 nm LED and a
660 nm laser both with 330 mW/cm<sup>2</sup> irradiance. Best irradiation time, PS concentration and ROS production profile
were determined showing that using 460 nm LED with 10 μM of PS, only 30 s of irradiation time was sufficient to
reduce 100 % <i>C. albicans</i> colonies.
Burns are frequently contamined by pathogenic microorganisms and the widespread occurrence of antibiotic resistant
strains of Pseudomonas aeruginosa in hospitals is a matter of growing concern. Hypocrellin B (HB) is a new generation
photosensitizer extracted from the fungus Hypocrella bambusae with absorption bands at 460, 546 and 584 nm.
Lanthanide ions change the HB molecular structure and a red shift in the absorption band is observed as well as an
increase in the singlet oxygen quantum yield. In this study, we report the use of HB:La<sup>+3</sup> to kill resistant strain of P.
aeruginosa infected burns. Burns were produced on the back of mice and wounds were infected subcutaneously with
1x10<sup>9</sup> cfu/mL of P. aeruginosa. Three-hours after inoculation, the animals were divided into 4 groups: control, HB:La<sup>+3</sup>,
blue LED and HB:La<sup>+3</sup>+blue LED. PDT was performed using 10μM HB:La+3 and 500mW light-emitting diode (LED)
emitting at λ=470nm±20nm during 120s. The animals of all groups were killed and the infected skin was removed for
bacterial counting. Mice with photosensitizer alone, light alone or untreated infected wounds presented 1x10<sup>8</sup> cfu/g while
mice PDT-treated showed a reduction of 2 logs compared to untreated control. These results suggest that HB:La<sup>+3</sup>
associated to blue LED is effective in diminishing antibiotic resistant strain P. aeruginosa in infected burns.