Background: Antimicrobial photodynamic therapy (aPDT) is a growing approach to treat skin and mucosal infections. Despite its effectiveness, investigators have explored whether aPDT can be further combined with antibiotics and antifungal drugs. Objective: To systematically assess the in vivo studies on the effectiveness of combinations of aPTD plus antimicrobials in the treatment of cutaneous and mucosal infections. Materials and methods: Searches were performed in four databases (PubMed, EMBASE, Cochrane library databases, ClinicaTrials.gov) until July 2018. The pooled information was evaluated according to the PRISMA guidelines. Results: 11 full-text articles were finally evaluated and included. The best aPDT combinations involved 5-aminolevulinic acid or phenothiazinium dye-based aPDT. In general, the combination shows benefits such as reducing treatment times, lowering drug dosages, decreasing drug toxicity, improving patient compliance and diminishing the risk of developing resistance. The mechanism of action may be that first aPDT damages the microbial cell wall or membrane, which allows better penetration of the antimicrobial drug. Limitations: The number of studies was low, the protocols used were heterogeneous, and there was a lack of clinical trials. Conclusions: The additive or synergistic effect of aPDT combined with antimicrobials could be promising to manage skin and mucosal infections, helping to overcome the microbial drug resistance.

Staphylococcus pseudintermedius is an opportunistic pathogen that has been identified as infectious agent or colonizer mainly in dogs. S. pseudintermedius has been also detected in humans and more specifically in people in contact with dogs. In this study, the possible S. pseudintermedius pet-to-human transmission was analyzed in four clinical human cases. Two patients were dog owners and S. pseudintermedius was also detected as colonizer in these healthy animals. S. pseudintermedius isolates from patients and dogs of the same household showed identical pulsed-field gel electrophoresis patterns, sequence types (STs), and antimicrobial resistance phenotypes and genotypes, and were methicillin susceptible. Resistance to erythromycin, clindamycin, tetracycline, trimetoprim-sulfamethoxazole, and/or ciprofloxacin was identified among S. pseudintermedius strains. The lineages ST241 and the new ST521 were detected in the strains of the two dog-owner patients, respectively. The strains from the other two patients presented two new STs, ST719 and ST720. To our knowledge, this is the first description of human infections caused by S. pseudintermedius in Spain.

Photoinactivation of Staphylococcus aureus has been achieved using a hexanuclear molybdenum cluster, [Mo ₆ I ₈ (CH ₃ COO) ₆ ] ²⁻ , supported on a polystyrene matrix.

Antimicrobial photodynamic therapy has been proposed as an alternative to suppress subgingival species. This results from the balance among Streptococcus sanguis, Streptococcus mutans and Candida albicans in the dental biofilm. Not all the photosensitizers have the same photodynamic effect against the different microorganims. The objective of this study is to compare in vitro the photodynamic effect of methylene blue (MB), rose Bengal (RB) and curcumin (CUR) in combination with white light on the cariogenic microorganism S. mutans, S. sanguis and C. albicans. Photodynamic therapy with MB, RB and CUR inhibited 6 log 10 the growth of both bacteria but at different concentrations: 0.31–0.62 μg/ml and 0.62–1.25 μg/ml RB were needed to photoinactivate S. mutans and S. sanguis, respectively; 1.25–2.5 μg/ml MB for both species; whereas higher CUR concentrations (80–160 μg/ml and 160–320 μg/ml) were required to obtain the same reduction in S. mutans and S. sanguis viability respectively. The minimal fungicidal concentration of MB for 5 log10 CFU reduction (4.5 McFarland) was 80–160 μg/ml, whereas for RB it ranged between 320 and 640 μg/ml. For CUR, even the maximum studied concentration (1280 μg/ml) did not reach that inhibition. Incubation time had no effect in all experiments. Photodynamic therapy with RB, MB and CUR and white light is effective in killing S. mutans and S. sanguis strains, although MB and RB are more efficient than CUR. C. albicans required higher concentrations of all photosensitizers to obtain a fungicidal effect, being MB the most efficient and CUR ineffective.

A hexanuclear molybdenum cluster [Mo₆I₈Ac₆]²⁻ (1) has been ionically bound onto macroporous (P_mp) and gel-type (P_gel) resins and their performance as materials for the photodynamic inactivation of microorganisms has been studied. It has been found that 1@P_mp in combination with light is able to reduce 99.999999% of the population of Gram-positive Staphylococcus aureus whereas the activity of 1@P_gel is limited to a 99.99% reduction at the same light dose. The same trend is observed with Gram-negative Pseudomonas aeruginosa. A comprehensive study of both materials has been performed using confocal laser scanning microscopy, thermogravimetric analysis, nitrogen porosimetry, steady state and time resolved fluorometries and diffuse reflectance spectroscopy. The photochemical generation of singlet oxygen (¹O₂) has been assessed using 9,10-dimethylanthracene as a trap for this reactive oxygen species. It can be concluded that the nature of the polymeric support is of paramount importance for the development of surfaces with bactericidal properties.