Comparative activity of ciprofloxacin, ofloxacin, levofloxacin, and erythromycin against Legionella species by broth microdilution and intracellular susceptibility testing in HL-60 cells

Diagn Microbiol Infect Dis. 1998 Jan;30(1):37-43. doi: 10.1016/s0732-8893(97)00174-0.

Abstract

Animal lung macrophages or human peripheral blood mononuclear cells have been used for testing intracellular activity of anti-Legionella antibiotics; such studies are labor intensive such that comparative antibiotic studies for the many Legionella species are few. We evaluated a human monocyte cell line (HL-60) as an alternative model. HL-60 (1.5 x 10(6) cells/well) was differentiated into adherent cell and infected with 1.5 x 10(7) CFU of Legionella pneumophilia (L. pneumophilia). Erythromycin and quinolones, ciprofloxacin, ofloxacin, and levofloxacin were added to cells at 1 and 8 x MIC. Percent (%) inhibition ratios equal to total L. pneumophila with agent divided by L. pneumophila without agent x 100 were determined at 48 h; lower ratios implied greater potency. By broth dilution in buffered yeast extract broth, the most potent agents against L. pneumophila were (MIC): ciprofloxacin (0.015-0.03), ofloxacin (0.015-0.03), levofloxacin (0.015-0.03), erythromycin (0.125-1.0 microgram/mL). In the intracellular model, the most potent inhibitors of L. pneumophila multiplication at 8 x MIC were (in order of potency) levofloxacin (24.2%), ciprofloxacin (30.6%), ofloxacin (37.1%), and erythromycin (55.0%). All the quinolones were highly active and significantly more potent against L. micdadei and L. bozemanii when compared to L. pneumophila.

Publication types

  • Comparative Study

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Anti-Infective Agents / pharmacology*
  • Ciprofloxacin / pharmacology
  • Erythromycin / pharmacology*
  • HL-60 Cells
  • Humans
  • Legionella / drug effects*
  • Legionella / growth & development
  • Legionella / isolation & purification
  • Legionella pneumophila / drug effects
  • Legionnaires' Disease / microbiology
  • Levofloxacin
  • Microbial Sensitivity Tests / methods*
  • Ofloxacin / pharmacology
  • Reproducibility of Results

Substances

  • Anti-Bacterial Agents
  • Anti-Infective Agents
  • Ciprofloxacin
  • Erythromycin
  • Levofloxacin
  • Ofloxacin