Evaluation of Antimicrobial Sensitivity to Tetracycline Exposed to Non-Thermal Plasma

Abstract

Tetracyclines comprise a large group of broad-spectrum antibiotics used in human and veterinary medicine. Its mechanism of action, via oral ingestion, is to inhibit bacterial protein synthesis, but a large amount (70%) is eliminated without being metabolized, which presents a risk for the arising of antibiotic-resistant species. In this study, the degradation of Tetracycline TC by non-thermal plasma NTP and the antimicrobial sensitivity of the treated solution are investigated. The degradation was followed by chromatographic analysis while the efficiency of NTP in inhibiting the action of TC on bacteria was evaluated by antimicrobial sensitivity test by disk diffusion method. The results showed a high rate of TC degradation, over 90%, in 10 min of NTP treatment for a 60 mL (107 mg L-1) sample and very slow increase up to 94% in 30 min. The antimicrobial sensitivity test of TC after degradation by NTP showed no antibiotic activity. Therefore, our findings are encouraging, since the removal efficiency is below the minimum threshold require, to prevent with high probability, outgrowth of antibiotic-resistant bacteria. In addition, the results confirm that the NTP treated solution is safe to the environment.