In vitro efficacy of hyperbaric oxygen therapy against Leishmania tropica promastigotes and amastigotes

Aim: To assess the efficiency of hyperbaric oxygen (HBO) therapy on L. tropica, which is the major causative agent of cutaneous leishmaniasis in Turkey. Materials and methods: The effects of HBO on Leishmania tropica promastigote and amastigote forms were studied at a pressure of 2.5 atmosphere absolute (ata). We examined the cytotoxic effect of HBO on promastigotes using the trypan blue exclusion test and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye-reduction assay. To investigate the effects of HBO treatment on the growth of the promastigotes, HBO-treated and non-HBO-treated cell culture flasks were incubated at 26 degrees C for 3 days, while the effects of HBO on L. tropica amastigotes were detected using the acridine orange staining method. Results: We observed that the cytotoxic effect emerged after 2 h and reached a maximum at 6 h with both methods. The number of live promastigotes was monitored for 24 h after treatment and there was a slight elevation at 2 h of treatment, but significant suppression was seen after 4 and 6 h of treatment (P < 0.001). We detected that the effect of HBO on L. tropica amastigote forms increased by 3.3%, 17.2%, and 38.5% at 2, 4, and 6 h, respectively. Conclusion: The results presented here indicate that HBO treatment could be used as supportive therapy in association with chemotherapeutic agents against L. tropica infection.