Screening of antibacterial drugs for antimicrobial activity against Pythium insidiosum.

We tested 25 isolates of Pythium insidiosum to investigate their susceptibility to antibacterial drugs that act through inhibition of protein synthesis or other mechanisms of action. We observed that tetracycline, erythromycin, linezolid, nitrofurantoin, Synercid (quinupristin and dalfopristin), chloramphenicol, clindamycin, cetrimide, and crystal violet had inhibitory activity against P. insidiosum. Those in vitro results suggest that antibacterials that inhibit protein synthesis should be the primary antimicrobials investigated for the treatment of pythiosis in animals and humans.

In vitro combination between antifungals and diphenyl diselenide against Cryptococcus species.

Cryptococcus species are an encapsulated fungal pathogen that cause cryptococcal meningitis. There are limited therapeutic options for this infection. The management includes the use of different antifungals such as amphotericin B, flucytosine, or fluconazole, either alone or in combination. However, numerous therapeutic failures, as well as the limited effectiveness of such therapeutics, have been described. Diphenyl diselenide is a chemically synthesised molecule with was found to have antimicrobial activity. In this study, we evaluated the antifungal activities of fluconazole, amphotericin B and flucytosine, in combination with diphenyl diselenide against 30 clinical isolates of Cryptococcus spp. using CLSI M27-A3 method and the checkerboard microdilution technique. Our results show that the combination of flucytosine and diphenyl diselenide displayed 100% of synergism. However, when we analysed (PhSe)2 plus AMB or FLZ we observed around 70% of indifference. Our results suggest that the combination of diphenyl diselenide with other antifungal agents deserves attention as a new option for the development of alternative therapies for cryptococcosis.