In Vitro Activities of Moxifloxacin, 127I-Moxifloxacin and 131I-Moxifloxacin Against Staphylococcus Aureus Biofilms

Objective: The aim of the study was to investigate the antimicrobial effect of Moxifloxacin (MXF), radio (Na131I) and cold\ud(K127I) iodinated MXF on methicillin susceptible Staphylococcus aureus ATCC 35556 (MSSA) biofilms.\udMethods: MXF was labeled with Na131I using the iodogen method. The optimum radiodination conditions for 131I-MXF\udwas determined by thin-layer radio chromatography studies. Thin-layer radio chromatography (TLRC) chromatograms were\udobtained by using Cyclone Plus Storage Phosphor System. The MICs of MXF, 127I-MXF and 131I-MXF were determined using\udthe microdilution broth method according to CLSI criteria. Time kill curves were performed over 24 h using an inoculum of\ud2×105 (CFU/mL). Biofilms were grown in microtitre plates, dyed with crystal violet and the mean optical density (OD630) was\udused for quantification. Biofilms were incubated MXF, 127I-MXF and 131I-MXF at various concentration (0.03 to 64 µg/mL).\udResults: MXF was labeled with 131I iodogen method. 131I-MXF was obtained with high a yield 95±3%. The MIC values for\udMXF, 127I-MXF and 131I-MXF was 0.06 µg/mL. Bactericidal activity was demonstrated at 0.25 µg/mL 4 hour for MXF, 127I-MXF\udand 131I-MXF. At MIC levels, MXF, 127I-MXF and 131I-MXF was not showed a marked reduction of metabolic activity in the S.\udaureus biofilm. The ODs of biofilm after incubation with an increasing antibiotic concentration were significantly lower than\udthe ODs of biofilms without antibiotic p≤005. The radiolabeled MXF was most effective than MXF, 127I-MXF in reducing the\udnumber of bacteria in biofilm. After 24 h incubation Log10 CFU/mL values for 32 µg/mL antibiotic concentration: Control,\udMXF, 127I-MXF and 131I-MXF were 9.5, 4.3, 4.8 and 3.1, respectively.\udConclusion: 131I and 127I were used alone there was no penetration of the S. aureus biofilm and no damage. In contrast\udour results demonstrate that the radiolabeled Moxifloxacin (131I-MXF) have potent anti-biofilm activity against S. aureus\udcompare to MXF, 127I-MXF and media control. This is suggested that, 131I labeled antibiotic may have harmful effect on\udbiofilm structure