Bacteria growing in vivo multiply much more slowly than in vitro. If the bactericidal activity of quinolones may be affected by an increase in generation time (g) was studied in batch cultures as well as under the well-controlled conditions of a continuous-flow culture. By limiting the nutrient supply, generation times were lengthened from approximately 0.45 to 1.5 h up to 3.9 h. Three recent clinical isolates each of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were exposed to twice the MIC of ciprofloxacin, norfloxacin, fleroxacin and ofloxacin. The ‘killing rates’ were calculated in analogy to the growth rate. The bactericidal activity of the quinolones tested against E. coli was minimally influenced by the reduced generation time and the effect against S.aureus was moderate. As compared to their rapidly growing counterparts (g = 0.4 h) slowly growing (g = 1.3 h) P. aeruginosa were killed even more effectively by ciprofloxacin (176% increase) fleroxacin (48% increase) norfloxacin (36% increase) and ofloxacin (86% increase). These changes may likely be due to adaptive responses of the outer membranes of the bacteria to the limited nutrient supply thereby sensitizing the bacteria to the bactericidal activity of quinolones.

This content is only available via PDF.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.