Antibiotic-Resistant and Non-Resistant Bacteria Display Similar Susceptibility to Dielectric Barrier Discharge Plasma.

Akikazu Sakudo,Tatsuya Misawa

doi:10.3390/ijms21176326

Abstract

Here, we examined whether antibiotic-resistant and non-resistant bacteria show a differential susceptibility to plasma treatment. Escherichia coli DH5α were transformed with pPRO-EX-HT-CAT, which encodes an ampicillin resistance gene and chloramphenicol acetyltransferase (CAT) gene, and then treated with a dielectric barrier discharge (DBD) plasma torch. Plasma treatment reduced the viable cell count of E. coli after transformation/selection and further cultured in ampicillin-containing and ampicillin-free medium. However, there was no significant difference in viable cell count between the transformed and untransformed E. coli after 1 min- and 2 min-plasma treatment. Furthermore, the enzyme-linked immunosorbent assay (ELISA) and acetyltransferase activity assay showed that the CAT activity was reduced after plasma treatment in both transformed and selected E. coli grown in ampicillin-containing or ampicillin-free medium. Loss of lipopolysaccharide and DNA damage caused by plasma treatment were confirmed by a Limulus test and polymerase chain reaction, respectively. Taken together, these findings suggest the plasma acts to degrade components of the bacteria and is therefore unlikely to display a differential affect against antibiotic-resistant and non-resistant bacteria. Therefore, the plasma method may be useful in eliminating bacteria that are recalcitrant to conventional antibiotic therapy.

Highlights

In recent years, the emergence of antibiotic-resistant bacteria has become a global problem
To obtain antibiotic-resistant bacteria, Escherichia coli DH5α was transformed with pPRO-EX-HT -CAT, which contains an ampicillin resistance gene and chloramphenicol acetyltransferase (CAT) gene
The viable cell number for E. coli transformed/selected with pPRO-EX-HT-CAT and cultured in LB liquid medium supplemented with ampicillin was lower than the control (2.40 × 106 ± 1.38 × 106 colony forming units per mL (CFU/mL), 0 min) (Figure 2)

Summary

Introduction

The emergence of antibiotic-resistant bacteria has become a global problem. One of the main drivers for the emergence of antibiotic-resistant bacteria is the excessive or inappropriate use of antibiotics [1,2]. Multiple resistant bacteria are a major problem in human and veterinary medicine, especially for nosocomial infections [3,6]. These antibiotic resistance genes are found on plasmids that carry genes conferring resistance to other non-β-lactam antibiotics such as aminoglycosides and trimethoprim-sulfamethoxazole [4]. E. coli harboring these plasmids are only susceptible to carbapenems and colistin

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Discussion

Conclusion