研究のタイプ: 医学/生物学の研究 (experimental study)

[無線周波電流は細菌バイオフィルムに対する抗生物質の効力を高める] med./bio.

A Radio Frequency Electric Current Enhances Antibiotic Efficacy against Bacterial Biofilms.

掲載誌: Antimicrob Agents Chemother 2004; 48 (12): 4662-4664

この研究は、ゲンタマイシンおよびオキシテトラサイクリンで処理された大腸菌バイオフィルムに対する「生体電気効果」を確認し、これまで用いられてきた直流電流の代わりに無線周波交流電流(10 MHz)を用いた新しい「生体電気効果」を提案した。「生体電気効果」とは、バイオフィルムの周囲の液体に微弱な直流電流を連続通電すると抗生物質の効果が劇的に増加すると報告されている現象であるが、そのメカニズムは未解明で、最適な電気パラメータも不明である。検討の結果、直流電流による「生体電気効果」の説明として候補に挙げられているもの(バイオフィルム内でのイオン輸送、電気分解による追加の殺生物剤の生成など)は、無線周波電磁界による「生体電気効果」には適用不能である;この新しい現象は、バイオフィルムマトリックスを形成する分子極性部分への無線周波電磁界の特異的作用による可能性を示唆したい、と報告している。

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研究目的(著者による)

Bacterial biofilms are notably resistant to antibiotic. It has been found that the addition of a weak continuous electric direct current (DC) to the liquid surrounding the biofilm can increase the efficacy of the antibiotic. This phenomenon, known as the bioelectric effect, has only been partially elucidated.
The aim of this study was to confirm the DC bioelectric effect with Escherichia coli biofilms treated with either gentamycin or with oxytetracycline. After this confirmation the DC was replaced by radiofrequency current at 10 MHz with the same effective intensity as the DC. At this frequency there is no transport of ions between the electrodes, no creation of new ions, and no electrolysis.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1:
  • DC/static
ばく露時間: continuous for 24 h
ばく露2: 10 MHz
ばく露時間: continuous for 24 h

ばく露1

主たる特性
周波数
  • DC/static
タイプ
  • electric field
ばく露時間 continuous for 24 h
ばく露装置
ばく露の発生源/構造
  • stainless steel electrodes, 12 cm apart
チャンバの詳細 Biofilm treatment chamber (14 x 8 x 5 cm³); the biofilm supports were placed perpendicular to the electrodes and were held in place by Teflon stubs.
ばく露装置の詳細 Four slides were placed in the chamber which was filled with M56
パラメータ
測定量 種別 Method Mass 備考
電流密度 60 A/m² unspecified 指定なし - -

ばく露2

主たる特性
周波数 10 MHz
ばく露時間 continuous for 24 h
Modulation
Modulation type unspecified
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
電力 5 W unspecified 指定なし - -

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
調査の時期:
  • ばく露後

研究の主なアウトカム(著者による)

The differences between the treated groups and the control groups in both sets of experiments (DC and radiofrequency) are significant. The DC data are substantially the same as those reported in other studies of the DC bioelectric effect. In the radiofrequency experiments also a synergy effect between radiofrequency current and the antibiotics was observed. The phenonmen, which is less prononuced than that found in the DC experiments, is interesting because the proposed explanations of the DC bioelectric effect (transport of ions within the biofilm, production of additional biocides by electrolysis, etc.) do not seem to be applicable. The authors suggest that this new phenomenon may be due to a specific action of the radiofrequency electromagnetic field upon the polar parts of the molecules forming the biofilm matrix.

研究の種別:

研究助成

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