Functions of natural killer cells (NK cells) can be modulated by environmental stimuli. However, the role of bacterial components in this modulation remains an area of ongoing research. This study investigates how bacterial supernatants influence NK cell function-including cytotoxicity, phenotype, and cytokine and mRNA production-following co-culture. These parameters were measured by flow cytometry and RT-PCR. We found that NK cells express TLR2 and TLR5, and that exposure to supernatants from ESKAPE group bacteria modified their cytotoxicity against JEG-3 and K-562 cell lines and their NKG2A and IL-10 mRNA levels. Our findings indicate that bacteria can modify NK cell features and their interactions with other cells in the microenvironment.