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Antimicrobial Agents and Chemotherapy, Mar 1995, 707-713, Vol 39, No. 3
C Pelletier, P Prognon and P Bourlioux
The antibacterial activity of nitroxoline (NIT), an antibiotic used in the
treatment of acute or recurrent urinary tract infections caused by
Escherichia coli, is decreased in the presence of Mg2+ and Mn2+ but not
Ca2+. In order to elucidate the interaction between this drug and the
divalent cations, spectrophotometric studies based on the natural
absorption of the nitroxoline moiety were conducted. In the presence of the
divalent metal ions, a shift in the NIT A448 suggested the formation of
drug-ion complexes, for which the stability followed the order Mn2+ >
Mg2+ > Ca2+. A clear correlation was found between the chelating
property and antibacterial activity of NIT; both were pH dependent. A
convenient colorimetric method for the determination of NIT uptake by
bacterial cells was also developed. Uptake was energy independent and
showed biphasic kinetics: a rapid association with cells and then a slower
increase in cell-associated NIT which reached a plateau. NIT uptake was
reduced in the presence of magnesium. The implications of metal ion
complexation and pH on the clinical efficacy of NIT are discussed.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Roles of divalent cations and pH in mechanism of action of nitroxoline against Escherichia coli strains
Department de Microbiologie et Immunologie, Centre d'Etudes Pharmaceutiques, Chatenay-Malabry, France.
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