AAC
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
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 Piddock, L. J. V.
Right arrow Articles by Pumbwe, L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Piddock, L. J. V.
Right arrow Articles by Pumbwe, L.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, March 2002, p. 808-812, Vol. 46, No. 3
0066-4804/02/$04.00+0     DOI: 10.1128/AAC.46.3.808-812.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Expression of Efflux Pump Gene pmrA in Fluoroquinolone-Resistant and -Susceptible Clinical Isolates of Streptococcus pneumoniae

Laura J. V. Piddock,* Maggie M. Johnson, S. Simjee,{dagger} and L. Pumbwe

Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom

Received 7 May 2001/ Returned for modification 18 July 2001/ Accepted 11 December 2001

Thirty-four ciprofloxacin-resistant (MIC >= 2 µg/ml) and 12 ciprofloxacin-susceptible clinical isolates of Streptococcus pneumoniae were divided into four groups based upon susceptibility to norfloxacin and the effect of reserpine (20 µg/ml). The quinolone-resistance-determining regions of parC, parE, gyrA, and gyrB of all ciprofloxacin-resistant clinical isolates were sequenced, and the activities of eight other fluoroquinolones, acriflavine, ethidium bromide, chloramphenicol, and tetracycline in the presence and absence of reserpine were determined. Despite a marked effect of reserpine upon the activity of norfloxacin, there were only a few isolates for which the activity of another fluoroquinolone was enhanced by reserpine. For most isolates the MICs of acriflavine and ethidium bromide were lowered in the presence of reserpine despite the lack of effect of this efflux pump inhibitor on fluoroquinolone activity. The strains that were most resistant to the fluoroquinolones were predominantly those with mutations in three genes. Expression of the gene encoding the efflux pump PmrA was examined by Northern blotting (quantified by quantitative competitive reverse transcriptase PCR) and compared with that of S. pneumoniae R6 and R6N. Within each group there were isolates that had high-, medium-, and low-level expression of this gene; however, increased expression was not exclusively associated with those isolates with a phenotype suggestive of an efflux mutant. These data suggest that there is another reserpine-sensitive efflux pump in S. pneumoniae that extrudes ethidium bromide and acriflavine but not fluoroquinolones.

* Corresponding author. Mailing address: Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom. Phone: 0121-414-6966. Fax: 0121-414-3454. E-mail: l.j.v.piddock{at}bham.ac.uk.

{dagger} Present address: U.S. Food and Drug Administration, Center for Veterinary Medicine, Laurel, MD 20708.

Antimicrobial Agents and Chemotherapy, March 2002, p. 808-812, Vol. 46, No. 3
0066-4804/02/$04.00+0     DOI: 10.1128/AAC.46.3.808-812.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Clin. Vaccine Immunol. Clin. Microbiol. Rev.
J. Clin. Microbiol. ALL ASM JOURNALS

Copyright © 2002 by the American Society for Microbiology. All rights reserved.