engleski

Nickel released during orthodontic treatment induces different effects on antimicrobial susceptibility of various commensal bacteria

AIM: To explore the interaction effect of antibiotic ciprofloxacin and nickel on the growth of Enterococcus faecalis and Staphylococcus aureus. MATERIALS AND METHODS: Staphylococcus aureus strain ATCC (American Type Cell Culture) 29213 and Enterococcus faecalis ATCC 29212 were used. Solutions of NiCl2 x 6H2O and ciprofloxacin were prepared. After determining the Minimum Inhibitory Concentrations (MIC) for nickel and ciprofloxacin, a checkerboard method was used to assess their cumulative effect on bacterial growth. Microtiter plates were read with a microplate reader. Exponential phase of bacterial growth was evaluated by constructing a logarithmic line and determining the linear function y=ax+b, where “a” is the slope of the line, i.e. growth rate. Interaction between the metal and antibiotic was assessed by Fractionary Inhibitory Concentration (FIC). RESULTS: MIC for ciprofloxacin for E. faecalis was 0.31 μg/ml and 0.62 μg/ml for S. aureus respectively. MIC for nickel was 1000 μg/ml for both bacteria. Concentration of ciprofloxacin significantly decreases growth rate of S. aureus with very large effect size and threshold concentration 0.62 μg/ml in comparison to 0.31 μg/ml (0.037±0.032 vs. 0.149±0, 024 ; p<0.001 ; η2=0.938). For E. faecalis the threshold concentration was 0.31 μg/ml (0.043±0.075 ; p<0.001 ; η2=0.729). FIC ranged from 1–2 for S. aureus, demonstrating an additive effect, and 2 – 5 for E. faecalis, demonstrating antagonism. CONCLUSION: An antagonistic effect of nickel and antibiotic ciprofloxacin was observed in E. faecalis, while an additive effect of same agents was seen in S. aureus.

nickel ; bacteria ; antibiotic ; resistance

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