This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pan, X.-S.
Right arrow Articles by Fisher, L. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Pan, X.-S.
Right arrow Articles by Fisher, L. M.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, August 2002, p. 2498-2506, Vol. 46, No. 8
0066-4804/02/$04.00+0     DOI: 10.1128/AAC.46.8.2498-2506.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Small-Colony Mutants of Staphylococcus aureus Allow Selection of Gyrase-Mediated Resistance to Dual-Target Fluoroquinolones

Xiao-Su Pan,1 Penelope J. Hamlyn,1,{dagger} Raquel Talens-Visconti,1,{ddagger} Fabiana L. Alovero,1,2 Ruben H. Manzo,2 and L. Mark Fisher1*

Molecular Genetics Group, Department of Biochemistry and Immunology, St. George's Hospital Medical School, University of London, London SW17 0RE, United Kingdom,1 Departamento de Farmacia, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Cordoba, Argentina2

Received 28 January 2002/ Returned for modification 30 March 2002/ Accepted 8 May 2002

Fluoroquinolones acting equally through DNA gyrase and topoisomerase IV in vivo are considered desirable in requiring two target mutations for emergence of resistant bacteria. To investigate this idea, we have studied the response of Staphylococcus aureus RN4220 to stepwise challenge with sparfloxacin, a known dual-target agent, and with NSFQ-105, a more potent sulfanilyl fluoroquinolone that behaves similarly. First-step mutants were obtained with both drugs but only at the MIC. These mutants exhibited distinctive small-colony phenotypes and two- to fourfold increases in MICs of NSFQ-105, sparfloxacin, and ciprofloxacin. No changes were detected in the quinolone resistance-determining regions of the gyrA, gyrB, grlA, or grlB gene. Quinolone-induced small-colony mutants shared the delayed coagulase response but not the requirement for menadione, hemin, or thymidine characteristic of small-colony variants, a subpopulation of S. aureus that is often defective in electron transport. Second-step mutants selected with NSFQ-105 had gyrA(S84L) alterations; those obtained with sparfloxacin carried a gyrA(D83A) mutation or a novel gyrB deletion ({Delta}RKSAL, residues 405 to 409) affecting a trypsin-sensitive region linking functional domains of S. aureus GyrB. Each mutation was associated with four- to eightfold increases in MICs of NSFQ-105 and sparfloxacin, but not of ciprofloxacin, which we confirm targets topoisomerase IV. The presence of wild-type grlB-grlA gene sequences in second-step mutants excluded involvement of topoisomerase IV in the small-colony phenotype. Growth revertants retaining mutant gyrA or gyrB alleles were quinolone susceptible, indicating that resistance to NSFQ-105 and sparfloxacin was contingent on the small-colony mutation. We propose that small-colony mutations unbalance target sensitivities, perhaps through altered ATP or topoisomerase levels, such that gyrase becomes the primary drug target. Breaking of target parity by genetic or physiological means eliminates the need for two target mutations and provides a novel mechanism for stepwise selection of quinolone resistance.

* Corresponding author. Mailing address: Molecular Genetics Group, Department of Biochemistry and Immunology, St. George's Hospital Medical School, University of London, Cranmer Terrace, London SW17 0RE, United Kingdom. Phone: 44 208 725 5782. Fax: 44 208 725 2992. E-mail: lfisher{at}sghms.ac.uk.

{dagger} Present address: Astex Technology Ltd., Cambridge CB4 0WE, United Kingdom.

{ddagger} Present address: Department of Pharmacy and Pharmaceutical Technology, University of Valencia, 46100 Valencia, Spain.

Antimicrobial Agents and Chemotherapy, August 2002, p. 2498-2506, Vol. 46, No. 8
0066-4804/02/$04.00+0     DOI: 10.1128/AAC.46.8.2498-2506.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Couto, I., Costa, S. S., Viveiros, M., Martins, M., Amaral, L. (2008). Efflux-mediated response of Staphylococcus aureus exposed to ethidium bromide. J Antimicrob Chemother 62: 504-513 [Abstract] [Full Text]  
  • Black, M. T., Stachyra, T., Platel, D., Girard, A.-M., Claudon, M., Bruneau, J.-M., Miossec, C. (2008). Mechanism of Action of the Antibiotic NXL101, a Novel Nonfluoroquinolone Inhibitor of Bacterial Type II Topoisomerases. Antimicrob. Agents Chemother. 52: 3339-3349 [Abstract] [Full Text]  
  • Robertson, G. T., Bonventre, E. J., Doyle, T. B., Du, Q., Duncan, L., Morris, T. W., Roche, E. D., Yan, D., Lynch, A. S. (2008). In Vitro Evaluation of CBR-2092, a Novel Rifamycin-Quinolone Hybrid Antibiotic: Studies of the Mode of Action in Staphylococcus aureus. Antimicrob. Agents Chemother. 52: 2313-2323 [Abstract] [Full Text]  
  • Vergison, A., Denis, O., Deplano, A., Casimir, G., Claeys, G., DeBaets, F., DeBoeck, K., Douat, N., Franckx, H., Gigi, J., Ieven, M., Knoop, C., Lebeque, P., Lebrun, F., Malfroot, A., Paucquay, F., Pierard, D., Van Eldere, J., Struelens, M. J. (2007). National survey of molecular epidemiology of Staphylococcus aureus colonization in Belgian cystic fibrosis patients. J Antimicrob Chemother 59: 893-899 [Abstract] [Full Text]  
  • Oyamada, Y., Ito, H., Inoue, M., Yamagishi, J.-i. (2006). Topoisomerase mutations and efflux are associated with fluoroquinolone resistance in Enterococcus faecalis.. J Med Microbiol 55: 1395-1401 [Abstract] [Full Text]  
  • Wetzstein, H.-G. (2005). Comparative Mutant Prevention Concentrations of Pradofloxacin and Other Veterinary Fluoroquinolones Indicate Differing Potentials in Preventing Selection of Resistance. Antimicrob. Agents Chemother. 49: 4166-4173 [Abstract] [Full Text]  
  • Campion, J. J., McNamara, P. J., Evans, M. E. (2004). Evolution of Ciprofloxacin-Resistant Staphylococcus aureus in In Vitro Pharmacokinetic Environments. Antimicrob. Agents Chemother. 48: 4733-4744 [Abstract] [Full Text]  
  • Masselot, F., Boulos, A., Maurin, M., Rolain, J. M., Raoult, D. (2003). Molecular Evaluation of Antibiotic Susceptibility: Tropheryma whipplei Paradigm. Antimicrob. Agents Chemother. 47: 1658-1664 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»