Avaliação in vitro do sinergismo da cetamina com derivados azólicos em micro-organismos na forma planctônica e em isolados formadores de biofilme

Abstract

The emergence of Candida spp. with resistance to antifungal compounds, mainly the azoles class, is a growing problem in hospitals around the world and are associated with a high morbidity and mortality, in addition to being related to a high economic burden at the hospital level. In this way combined drug therapy has become one of the most widely used and effective strategies to alleviate this problem. In the present work, we evaluated the synergistic effect of ketamine with two azole derivatives, itraconazole (ITRA) and fluconazole (FLC), against strains of Candida spp. resistant to fluconazole and to the biofilm formed of C. albicans and we decided to evaluate the genotoxic and mutagenic effects of ketamine on peripheral blood leukocytes (PBLs) and Salmonella typhimurium (TA98, TA97a, TA100, and TA102) through several well-established experimental protocols based on different parameters in the presence or not of exogenous metabolizing S9 fraction. The evaluation of the drug interaction was determined by calculating the fractional inhibitory concentration and flow cytometry techniques. We conclude that ketamine, when administered in combination with fluconazole or itraconazole, exhibited activity against strains of Candida spp. resistant to fluconazole, which probably occurs through changes in membrane integrity of yeast cells and generation of reactive oxygen species, mitochondrial dysfunction and DNA damage that could lead to death by apoptosis. The evaluation of biofilm forming isolates after treatment showed statistically significant reductions in biofilm cell activity (P <0.05). Our data revealed that ketamine induces a weak cytotoxic effect on PBLs after 24 h and is devoided of hemolytic effects. A small amount of DNA strand breaks levels were detected in the modified comet assay (employment of FPG enzyme) only at highest concentrations (500 and 700 µg/mL) of ketamine, highlighting our pro-oxidant data regarding ketamine. However, the oxidative DNA lesions were almost completely repaired which reflects in the lack of mutagenesis (micronuclei and chromosomal aberrations) on PBLs and no increases in revertants numbers on S. typhimurium/microsome test (500 to 5,000 µg/plate). In summary, ketamine is a weak oxidative DNA damaging agent and is devoid of mutagenic properties on eukaryotic and prokaryotic models.