Photodynamic and antibiotic therapy in combination against bacterial infections: efficacy, determinants, mechanisms, and future perspectives.

Antibiotic treatment, the mainstay for the control of bacterial infections, is greatly hampered by the global prevalence of multidrug-resistant (MDR) bacteria. Photodynamic therapy (PDT) is effective against MDR infections, but PDT-induced bacterial inactivation is often incomplete, causing the relapse of infections. Combination of PDT and antibiotics is a promising strategy to overcome the limitation of both antibiotic treatment and PDT, exerting increased disinfection efficacy on MDR bacterial pathogens versus either of the monotherapies alone. In this review, we present an overview of the therapeutic effects of PDT/antibiotic combinations that have been developed. We further summarize the influencing factors and the governing molecular mechanisms of the therapeutic outcomes of PDT/antibiotic combinations. In the end, we provide concluding remarks on the strengths, limitations, and future research directions of PDT/antibiotic combination therapy to guide its appropriate usage and further development.

Atividade antifúngica do a-terpinen sobre Candida albicans / Antifungal activity of a-terpinen on Candida albicans

Objetivo: avaliar a atividade antifúngica do a- terpinen sobre culturas planctonicas e biofilme de Candida albicans. Material e Métodos: Primeiramente, foi determinada a Concentração Inibitória Mínima (CIM) e a Concentração Fungicida Mínima (CFM) do a-terpinen sobre microrganismos planctônicos. A Nistatina foi utilizada como controle positivo. Biofilme de Candida albicans foi desenvolvido e, após o tratamento com diferentes concentrações de α-terpinen, foi quantificado em UFC/mL, além da atividade metabólica das células ser avaliada por XTT. Resultados: a menor concentração capaz de inibir o crescimento (CIM) foi 0,2 % para o a-terpinen e 4 µg/mL para a Nistatina. Na CIM, os resultados mostraram que a partir da concentração 0,05 % de α-terpinen e 2 µg/mL de Nistatina houve diminuição de C.albicans quando comparado ao controle. A CFM foi para a-terpinen 0,2 % e Nistatina 8 µg/mL. Na quantificação as concentrações eficazes foram de α-terpinen (0,1%) e Nistatina (128µg/mL), e no teste do XTT, observou-se que α -terpinen (0,1%) e Nistatina (256µg/mL) diminuem a viabilidade quando comparado com o controle. Conclusão: Assim, pode-se afirmar que α -terpineol pode ser uma alternativa para tratamento de infecções fúngicas.

Objective: to evaluate the antifungal activity of a-terpinen on planktonic cultures and biofilm of Candida albicans. Material and Methods: first, Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (CFM) of a-terpinen were determined. Nystatin was used as a positive control. Biofilm of Candida albicans was developed and, after treatment with different concentrations of a-terpinen, was quantified in CFU/mL, in addition to metabolic activity of the cells being evaluated by XTT. Results: the lowest concentration able to inhibit the growth (MIC) was 0.2% for a-terpinen and 4 µg / mL for Nystatin. Results showed that from the concentration 0.05% of α -terpinen and 2 µg / mL of Nystatin, there was a decrease of Candida albicans when compared to the control, in planktonic culture. CFM was 0.2% for α -terpinen and 8 µg / mL for Nystatin. Regarding the quantification, effective concentrations were α-terpinen (0.1%) and Nystatin (128 µg/mL), and in the XTT test, α-terpinen (0.1%) and Nystatin (256 µg/mL) decreased metabolic activity when compared to control. Conclusion: Thus, it can be stated that a-terpineol may be an alternative for the treatment of fungal infections.