Enhancing effect on alkalinization of the medium on the activity of erythromycin against gram-negative bacteria.

L. D. Sabath, V. Lorian, D. A. Gerstein, P. B. Loder, M. Finland

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The antibacterial activity of erythromycin was markedly enhanced by alkalinization of the culture medium or urine within the clinical range (pH 6.0 to 8.2). This effect was demonstrated against recent isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter sp., and Pseudomonas aeruginosa, as well as against Staphylococcus aureus and Streptococcus faecalis. The urine of normal volunteers was made alkaline by ingestion of sodium bicarbonate or acetazolamide (Diamox) during administration of 1.0 g of erythromycin every 8 hr; such urine was capable of inhibiting E. coli and K. pneumoniae even when diluted up to (in one instance) 128 times with broth of the same pH as the urine. Undiluted urine of the same subjects, without alkalinization, was seldom capable of inhibiting these organisms. The range of pH (6.6 to 8.6) over which the antibacterial effect was enhanced coincided with that over which there was decreasing ionization of a basic group.
Original languageUndefined/Unknown
Pages (from-to)1288-1292
Number of pages5
JournalApplied Microbiology
Issue number9
StatePublished - 1968


  • Bacteria/de [Drug Effects]
  • Culture Media
  • Enterobacter/de [Drug Effects]
  • Enterococcus faecalis/de [Drug Effects]
  • Erythromycin/pd [Pharmacology]
  • Erythromycin/ur [Urine]
  • Escherichia coli/de [Drug Effects]
  • Humans
  • Hydrogen-Ion Concentration
  • Klebsiella/de [Drug Effects]
  • Proteus/de [Drug Effects]
  • Pseudomonas aeruginosa/de [Drug Effects]
  • Staphylococcus/de [Drug Effects]

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