Evaluation of a human monocytic cell line THP-1 model for assay of the intracellular activities of antimicrobial agents against Legionella pneumophila

Hiromu Takemura, Hiroyuki Yamamoto, Hiroyuki Kunishima, Hideaki Ikejima, Takashi Hara, Keiji Kanemitsu, Shigemi Terakubo, Yoko Shoji, M. Kaku, Mitsuo Shimada

研究成果: Article査読

20 被引用数 (Scopus)

抄録

We examined the intracellular activities of 11 antimicrobial agents against Legionella pneumophila using a human monocyte-derived cell line, THP-1. Colony counting and microscopic examination of L. pneumophila co-incubated with THP-1 cells (5 x 105 cells/well) were performed. Both extra- and intra-cellular multiplication of L. pneumophila were observed and were dependent on the inoculum of L. pneumophila in the culture; L. pneumophila did not grow in the cell culture medium alone. Light microscopic examination confirmed that extracellular L. pneumophila originated from THP-1 cells disrupted by bacterial multiplication. L. pneumophila multiplied by 3-4 logs after 24 h incubation with THP-1 cells and their number remained stable at 106-107 cfu/mL until 72 h. The results of viability studies using four antimicrobial agents-ciprofloxacin, erythromycin, minocycline and rifampicin-demonstrated that our system was suitable for the intracellular activity assay. We used a concept of 'minimum extracellular concentration inhibiting intracellular multiplication' (MIEC) to evaluate the intracellular activity of antimicrobial agents. The MIECs of three β-lactams were markedly higher than their conventional MICs while those of macrolides, quinolones, rifampicin and minocycline were similar to their MICs. Our results suggest that evaluation of the clinical efficacy of drugs against L. pneumophila should include determination of their intracellular activity against the bacteria, which could be measured using our assay system in THP-1 cells.

本文言語English
ページ(範囲)589-594
ページ数6
ジャーナルJournal of Antimicrobial Chemotherapy
46
4
DOI
出版ステータスPublished - 2000

ASJC Scopus subject areas

  • 薬理学
  • 微生物学(医療)
  • 感染症
  • 薬理学(医学)

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