Enhanced activity of streptomycin and chloramphenicol against intracellular Escherichia coli in the J774 macrophage cell line mediated by liposome delivery

M. Stevenson, A. J. Baillie, R. M.E. Richards

Research output: Contribution to journalArticle

49 Scopus citations


Streptomycin and chloramphenicol were entrapped within large neutral or anionic unilamellar vesicles of egg phosphatidylcholine prepared by an ether injection method. Both antibiotics in liposomal form were inactive against Escherichia coli in a simple tube dilution assay. A comparison was made of the activities of the free and liposomal forms of the antibiotics against E. coli located within the macrophages of the J774.2 murine cell line. The apparent intracellular antibacterial activity of both antibiotics was increased more than 10-fold by entrapment in neutral liposomes and in the case of chloramphenicol in anionic liposomes containing phosphatidylserine. Anionic liposomes containing phosphatidic acid were much less effective carriers than neutral liposomes for either antibiotic in this in vitro system. Incubation at 4° C of cells with liposomes containing antibiotic or carboxyfluorescein inhibited intracellular antibacterial activity and cell-associated fluorescence. The high intracellular activity of the liposomal antibiotics is consistent with their phagocytic uptake by the macrophages followed by intracellular liposomal degradation and antibiotic release. Liposomal modification of cellular uptake and intracellular distribution of antibiotics may be used to extend the activity of existing and new agents against intracellular infection of the reticuloendothelial system.

Original languageEnglish (US)
Pages (from-to)742-749
Number of pages8
JournalAntimicrobial agents and chemotherapy
Issue number5
StatePublished - Jan 1 1983
Externally publishedYes


ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

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