Effects of acetyl salicylate and ibuprofen on fluoroquinolone MICs on Salmonella enterica serovar typhimurium in vitro

In this study, the effects of acetylsalicylate and ibuprofen at 2, 4 and 8 mM concentration were investigated on ofloxacin, ciprofloxacin, levofloxacin and pefloxacin minimum inhibitory concentrations (MICs) for 14 Salmonella enterica serovar typhimurium clinical isolates, one standard strain (SZH KUEN 557), SH7616 (acr mutant), SH5014 (parent strain of acr mutant) and PP120 (soxRS mutant) strains. All isolates were susceptible to the 4 fluoroquinolones. In the presence of 2, 4 and 8 mM acetylsalicylate and ibuprofen, 2- to 8-fold increases were observed in fluoroquinolone MICs. This rise was higher, especially in the presence of acetylsalicylate. In spite of this rise, none of the MICs were in the range of resistance limits in vitro. Except for a 2-fold increase in levofloxacin MICs, we did not observe any difference in MICs of ofloxacin, ciprofloxacin, and pefloxacin in the presence of 2, 4 and 8 mM acetylsalicylate and ibuprofen for SH7616 and PP120 strains. According to the in vitro results of this study, it can be suggested that use of acetylsalicylate or ibuprofen together with clinical treatment of bacteria, especially bacteria which show intermediate resistance, will cause resistance. However, since clinical data are insufficient, further studies are needed.