Photodynamic therapy controls of Staphylococcus aureus intradermal infection in mice

Infections caused by Staphylococcus aureus lead to skin infections, as well as soft tissues and bone infections. Given the communal resistance to antibiotics developed by strains of this bacterium, photodynamic therapy emerges as a promising alternative treatment to control and cure infections. Females of the Balb/C mice were infected with 10⁸ CFU of methicillin-resistant S. aureus (MRSA) and divided into four distinct groups: P-L- (negative control group), P+L- (group exposed only to curcumin), P-L+ (group exposed only to LED incidence of 450 nm, 75 mW/cm², and 54 J/cm² for 10 min), and P+L+ (group exposed to curcumin followed by 10 min of LED irradiation) (n = 24). The mice were euthanized 48 and 72 h after infection, and biologic materials were collected for analysis of the bacterial load, peripheral blood leukocyte counts, and draining lymph nodes cell counts. The normalization of data was checked and the ANOVA test was applied. The bacterial load in the draining lymph node of P+L+ group was lower when compared to the control groups 72 h post infection (p < 0.0001), indicating that the LED incidence associated with curcumin controls of the staphylococci intradermal infection. The number of the total lymph node cells shows to be lower than control groups in the two availed times (p < 0.01). The histological analysis and the counting of white blood cells did not show differences among cells in the blood and in the tissue of infection. This is the first report showing that photodynamic therapy may be effective against MRSA infection in a murine model of intradermal infection.