JB
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 Robertson, G. T.
Right arrow Articles by Winkler, M. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Robertson, G. T.
Right arrow Articles by Winkler, M. E.

 Previous Article  |  Next Article 

Journal of Bacteriology, December 2002, p. 6987-7000, Vol. 184, No. 24
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.24.6987-7000.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Vancomycin Tolerance Induced by Erythromycin but Not by Loss of vncRS, vex3, or pep27 Function in Streptococcus pneumoniae

Gregory T. Robertson,1 Jingyong Zhao,1 Bhushan V. Desai,2 William H. Coleman,2 Thalia I. Nicas,1 Raymond Gilmour,1 Leo Grinius,3 Donald A. Morrison,2 and Malcolm E. Winkler1*

Infectious Diseases Research Division, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285,1 University of Illinois at Chicago, Chicago, Illinois 60607,2 Procter and Gamble Pharmaceuticals, Mason, Ohio 450403

Received 30 May 2002/ Accepted 16 September 2002

Vancomycin-tolerant Streptococcus pneumoniae is a growing problem among drug-resistant human pathogens. Some vancomycin-tolerant pneumococci have been reported to carry mutations in loci encoding a two-component regulatory system designated VncRS or in a proximal ABC transporter, Vex. A model was advanced proposing that the tolerance phenotype resulted from the inability of a vncS mutant to respond to the Vex-transported Pep27 "death peptide" signal and dephosphorylate VncR, thereby preventing relief of repression of autolytic and other cell death functions in response to antibiotics. To explore this hypothesis, we constructed mutations in vncS, vncR, vex3, and pep27 in S. pneumoniae strain R6 and two additional genetic backgrounds. The lytic responses of the isogenic {Delta}vncS, {Delta}vex3, {Delta}vncR, and {Delta}pep27 mutants, but not a {Delta}lytA strain, to vancomycin were indistinguishable from that of the parent strain. {Delta}vncS strains also failed to exhibit tolerance to vancomycin at various doses in multiple media and showed wild-type sensitivity to other classes of autolysis-inducing antibiotics. In contrast, addition of subinhibitory levels of the antibiotic erythromycin led to tolerance to vancomycin during late, but not early, exponential-phase growth in a {Delta}vncS strain, in the parent strain R6, and in two other strains bearing erythromycin resistance markers, namely, a {Delta}vncR strain and an unrelated {Delta}comD strain that is defective in competence-quorum sensing. Thus, this tolerance effect resulted from changes in cell growth or other erythromycin-dependent phenomena and not inactivation of vncS per se. Consistent with these results, and in contrast to a previous report, we found that a synthetic form of Pep27 did not elicit lytic or nonlytic killing of pneumococci. Finally, microarray transcriptional analysis and ß-galactosidase reporter assays revealed VncS-dependent regulation of the vex123 gene cluster but did not support a role for VncRS in the regulation of autolytic or other putative cell death loci. Based on these findings, we propose that vancomycin tolerance in S. pneumoniae does not result from loss of vncS function alone.

* Corresponding author. Mailing address: Lilly Research Laboratories, Drop Code 1543, Lilly Corporate Center, Indianapolis, IN 46285. Phone: (317) 433-0095. Fax: (317) 276-9159. E-mail: Winkler_Malcolm_E{at}Lilly.com.

Journal of Bacteriology, December 2002, p. 6987-7000, Vol. 184, No. 24
0021-9193/02/$04.00+0     DOI: 10.1128/JB.184.24.6987-7000.2002
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]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

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