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Antimicrobial Agents and Chemotherapy, May 2005, p. 1753-1760, Vol. 49, No. 5
0066-4804/05/$08.00+0     doi:10.1128/AAC.49.5.1753-1760.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

In Vitro Assessment of the Further Potential for Development of Fluoroquinolone Resistance in Neisseria meningitidis

Tiffany R. Shultz,1,3 Peter A. White,2 and John W. Tapsall1,3*

Department of Microbiology, South Eastern Area Laboratory Service, The Prince of Wales Hospital, Sydney 2031,1 School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney 2052,2 School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney 2052, Australia3

Received 21 October 2004/ Returned for modification 31 October 2004/ Accepted 16 January 2005

We examined the potential for the development of fluoroquinolone resistance in Neisseria meningitidis by cultivating two clinical isolates of meningococci in the presence of concentrations of ciprofloxacin at and about the predetermined MIC. The quinolone resistance determining regions (QRDRs) of gyrA and parC of 50 stable quinolone-resistant mutants derived in vitro were sequenced and compared with QRDR alterations reported in clinical isolates of quinolone-resistant meningococci and gonococci. MICs to ciprofloxacin and trovafloxacin were determined and sequence changes were correlated with quinolone MICs. Ciprofloxacin and trovafloxacin MICs of the in vitro-derived quinolone-resistant mutants ranged up to 16 mg/liter. Single GyrA alterations were the first change detected and were accompanied by raised MICs, followed by double GyrA changes and still higher MICs. MICs increased further as single ParC substitutions appeared and these were always in the presence of a single or double GyrA change. GyrA changes occurred at positions 91 and 95 with substitutions of Asp-95->Asn and Thr-91->Ala and Ile. Changes in the parC QRDR occurred at positions 85, 86, and 91 with four substitutions, Gly-85->Asp, Asp-86->Asn, Glu-91->Gly, and Glu-91->Lys, detected. The nature of the individual QRDR substitution appeared to influence the level of quinolone resistance expressed, and this varied with the quinolone agent examined. Close similarities occurred between the sequence and nature of QRDR changes in clinical and in vitro-generated quinolone-resistant mutants and with those previously reported for clinical and in vitro-generated quinolone-resistant gonococci. This suggests that quinolone resistance in meningococci may arise in the same manner and reach similar levels in vivo to those seen in quinolone-resistant Neisseria gonorrhoeae.

* Corresponding author. Mailing address: Department of Microbiology, South Eastern Area Laboratory Service, The Prince of Wales Hospital, Sydney 2031, Australia. Phone: 612-9382-9079. Fax: 612-9398-4275. E-mail:j.tapsall{at}unsw.edu.au.

Antimicrobial Agents and Chemotherapy, May 2005, p. 1753-1760, Vol. 49, No. 5
0066-4804/05/$08.00+0     doi:10.1128/AAC.49.5.1753-1760.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Enriquez, R., Abad, R., Salcedo, C., Perez, S., Vazquez, J. A. (2008). Fluoroquinolone resistance in Neisseria meningitidis in Spain. J Antimicrob Chemother 61: 286-290 [Abstract] [Full Text]  
  • Mehta, G., Goyal, R. (2007). Emerging fluoroquinolone resistance in Neisseria meningitidis in India: cause for concern. J Antimicrob Chemother 59: 329-330 [Full Text]  
  • Jorgensen, J. H., Crawford, S. A., Fulcher, L. C., Glennen, A., Harrington, S. M., Swenson, J., Lynfield, R., Murray, P. R., Tenover, F. C. (2006). Multilaboratory Evaluation of Disk Diffusion Antimicrobial Susceptibility Testing of Neisseria meningitidis Isolates.. J. Clin. Microbiol. 44: 1744-1754 [Abstract] [Full Text]  


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