Effect of antibiotic class and concentration on the release of lipopolysaccharide from Escherichia coli.
The ability of six antibiotics from different classes to release radiolabeled lipopolysaccharide (LPS) from a phenotypically smooth galE mutant of Escherichia coli O111:B4 was examined. Antibiotic concentrations were 0.0625-512 micrograms/mL. LPS release increased as a function of the antibiotic concentration, reaching a limit at or near the concentration that killed the majority of bacteria. The maximum amount of LPS released by polymyxin B was 40.6% +/- 0.9%, by gentamicin 58.2% +/- 2.5%, by ciprofloxacin 65.8% +/- 2.5%, by ceftazidime 73.1% +/- 0.9%, by tetracycline 75.3% +/- 10.0%, and by imipenem 79.7% +/- 2.3%. In timed experiments, ceftazidime released 61.9% +/- 1.2%, imipenem 51.1% +/- 8.8%, and tetracycline 39.7% +/- 4.4% of the LPS within the first hour of incubation, whereas polymyxin B released 13.5% +/- 1.9%, gentamicin 9.8% +/- 3.6%, and ciprofloxacin 12.7% +/- 2.6% of the LPS (P < .05). Fluoro-radiography and immunoblot analyses revealed similar migration patterns for antibiotic-released and cell-bound LPS on SDS-PAGE gels, suggesting similar O-polysaccharide content in the two LPS fractions. The amount and rate of LPS release from an E. coli strain was dependent upon antibiotic class and concentration.
Evans
M E
ME
Department of Medicine, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, Bethesda, MD 20814-4799.
Pollack
M
M
D000900:Anti-Bacterial Agents / Q000145:classification / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D005839:Gentamicins / Q000494:pharmacology; D015378:Imipenem / Q000494:pharmacology; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000378:metabolism*; D011112:Polymyxin B / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008070:Lipopolysaccharides; D002939:Ciprofloxacin; D015378:Imipenem; D002442:Ceftazidime; D013752:Tetracycline; D011112:Polymyxin B