The glycopeptides (GP) vancomycin (Vm) and teicoplanin (Tco) are the agents of choice in treating infections caused by methicillin-resistant staphylococci which are often multiply resistant to other commonly used agents. GP resistance has been recognized among the less-pathogenic coagulase-negative staphylococcal species for many years. Of great concern has been the recent emergence of intermediate GP resistance in methicillin-resistant S. aureus isolates obtained from patients who did respond to Vm therapy in Japan and the United States. Although many biochemical correlates of GP resistance among staphylococci have been identified, the mechanism of resistance is still unclear. Moreover, techniques for identifying resistant isolates in the clinical laboratory have proved insufficient and unreliable. Therefore, random approaches to scan the genome of GP-resistant clinical isolates for determinants of GP resistance may prove to be an effective means to identify the resistance mechanism. We propose to perform several complementary random genomic scanning techniques, transposon (Tn) mutagenesis, screening of plasmid DNA libraries produced from GP-resistant clinical isolates and mRNA differential display. Tn mutagenesis of GP-resistant isolates may lead to identification of factors essential for GP resistance. Screening plasmid libraries will identify loci sufficient for resistance and mRNA differential display will lead to the identification of genes that are differentially expressed between GP susceptible and resistant strains. Putative determinants identified by these techniques will be used in complementation analyses and insertional inactivation experiments to establish their role in resistance. We have already isolated a Vm-susceptible Tn551 mutant from a laboratory-derived Vm-resistant strain, 523k. We propose to identify the locus flanking the Tn551 insertion in 523k responsible for decreasing the resistance phenotype. The GP-resistant clinical isolates will also be used directly in the Tn mutagenesis studies, library screening and mRNA differential display. These strategies could reveal the mechanism of resistance leading to identification of novel targets for antimicrobial therapy and detection of resistant isolates.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Small Research Grants (R03)
Project #
1R03AI044999-01
Application #
2833389
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Program Officer
Heyse, Stephen P
Project Start
1999-09-01
Project End
2002-08-31
Budget Start
1999-09-01
Budget End
2000-08-31
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Chicago
Department
Pediatrics
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
Yin, Shaohui; Daum, Robert S; Boyle-Vavra, Susan (2006) VraSR two-component regulatory system and its role in induction of pbp2 and vraSR expression by cell wall antimicrobials in Staphylococcus aureus. Antimicrob Agents Chemother 50:336-43
Mongkolrattanothai, Kanokporn; Boyle, Susan; Murphy, Trudy V et al. (2004) Novel non-mecA-containing staphylococcal chromosomal cassette composite island containing pbp4 and tagF genes in a commensal staphylococcal species: a possible reservoir for antibiotic resistance islands in Staphylococcus aureus. Antimicrob Agents Chemother 48:1823-36
Boyle-Vavra, Susan; Yin, Shaohui; Challapalli, Mamatha et al. (2003) Transcriptional induction of the penicillin-binding protein 2 gene in Staphylococcus aureus by cell wall-active antibiotics oxacillin and vancomycin. Antimicrob Agents Chemother 47:1028-36
Daum, Robert S; Ito, Teruyo; Hiramatsu, Keiichi et al. (2002) A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds. J Infect Dis 186:1344-7
Hussain, Farid M; Boyle-Vavra, Susan; Shete, Priya B et al. (2002) Evidence for a continuum of decreased vancomycin susceptibility in unselected Staphylococcus aureus clinical isolates. J Infect Dis 186:661-7
Boyle-Vavra, S; Labischinski, H; Ebert, C C et al. (2001) A spectrum of changes occurs in peptidoglycan composition of glycopeptide-intermediate clinical Staphylococcus aureus isolates. Antimicrob Agents Chemother 45:280-7
Boyle-Vavra, S; Carey, R B; Daum, R S (2001) Development of vancomycin and lysostaphin resistance in a methicillin-resistant Staphylococcus aureus isolate. J Antimicrob Chemother 48:617-25
Boyle-Vavra, S; Hahm, J; Sibener, S J et al. (2000) Structural and topological differences between a glycopeptide-intermediate clinical strain and glycopeptide-susceptible strains of Staphylococcus aureus revealed by atomic force microscopy. Antimicrob Agents Chemother 44:3456-60