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Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry
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Metabolic and ultrastructural effects induced by ciprofloxacin in Staphylococcus aureus during the postantibiotic

M Gottfredsson1, H Erlendsdóttir, R Kolka

  • 1Department of Microbiology, Reykjavik City Hospital, Iceland.

Scandinavian Journal of Infectious Diseases. Supplementum
|January 1, 1990
PubMed

Insights

New quinolone antibacterials cause a postantibiotic effect (PAE) in bacteria. Increased DNA synthesis and bacterial swelling observed during PAE suggest a potential common mechanism for this effect.

Area of Science:

  • Microbiology
  • Pharmacology

Background:

  • New quinolone antibacterial agents exhibit a postantibiotic effect (PAE) lasting 1-4 hours in bacteria.
  • The precise mechanism underlying this bacterial PAE remains largely unknown.

Purpose of the Study:

  • To investigate the mechanism of the postantibiotic effect (PAE) induced by ciprofloxacin in Staphylococcus aureus.
  • To examine the impact of ciprofloxacin exposure on bacterial DNA synthesis and ultrastructure during the PAE.

Main Methods:

  • Exposure of S. aureus ATCC 25923 to ciprofloxacin (1-16x MIC) for 1 hour.
  • Measurement of DNA synthesis (3H-thymidine incorporation) post-drug removal.
  • Ultrastructural analysis using electron microscopy after exposure to 2x MIC ciprofloxacin.

Main Results:

  • DNA synthesis per organism increased progressively after ciprofloxacin removal, peaking at 1.5 hours.
  • Maximal 3H-thymidine incorporation correlated directly with PAE duration.
  • Electron microscopy revealed bacterial swelling and cytoplasmic vacuolization during the PAE.

Conclusions:

  • Increased DNA synthesis and metabolic activity during the PAE suggest a potential common underlying mechanism.
  • The physiological significance of enhanced DNA synthesis post-ciprofloxacin exposure requires further investigation.

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