Document Detail

Antimicrobial activity of quinupristin-dalfopristin (RP 59500, Synercid) tested against over 28,000 recent clinical isolates from 200 medical centers in the United States and Canada.
MedLine Citation:
PMID:  9635235     Owner:  NLM     Status:  MEDLINE    
A total of 200 medical center laboratories in the USA and Canada contributed results of testing quinupristin-dalfopristin, a streptogramin combination (formerly RP 59500 or Synercid), against 28,029 Gram-positive cocci. Standardized tests [disk diffusion, broth microdilution, Etest (AB BIODISK, Solna, Sweden)] were utilized and validated by concurrent quality control tests. Remarkable agreement was obtained between test method results for characterizing the collection by the important emerging resistances: 1) oxacillin resistance among Staphylococcus aureus (41.0 to 43.7%); 2) vancomycin resistance among Enterococcus faecium (50.0 to 52.0%); and 3) the penicillin nonsusceptible rate for pneumococci (31.1% overall, with 10.6% at MICs of > or = 2 micrograms/mL). The quinupristin-dalfopristin MIC90 for oxacillin-susceptible and -resistant S. aureus was 0.5 microgram/mL and 1 microgram/mL, respectively. The quinupristin-dalfopristin MIC90 for vancomycin-resistant E. faecium was 1 microgram/mL, and only 0.2% of isolates were resistant. Other Enterococcus species were generally not susceptible to the streptogramin combination but were usually inhibited by ampicillin (86 to 97% susceptible; MIC50, 1.0 microgram/mL) or vancomycin (86 to 95%; MIC50, 1.0 microgram/mL). Among all tested enterococci, the rate of vancomycin resistance was 16.2%. The quinupristin-dalfopristin MIC90 (0.75 microgram/mL) for 4,626 tested Streptococcus pneumoniae strains was not influenced by the penicillin or macrolide susceptibility patterns. When five regions in the USA and Canada were analyzed for significant streptogramin and other antimicrobial spectrum differences, only the Farwest region had lower numbers of streptogramin-susceptible E. faecium. Canadian strains were generally more susceptible to all drugs except chloramphenicol and doxycycline when tested against E. faecalis (73% and 89% susceptible, respectively). The U.S. Southeast region had S. pneumoniae strains less susceptible to macrolides (73%) but had more susceptibility among E. faecium isolates tested against vancomycin and ampicillin. The Northeast region of the USA had the greatest rate of vancomycin resistance among enterococci. Strains retested by the monitor because of quinupristin-dalfopristin resistance (MICs, > or = 4 micrograms/mL) were generally not confirmed (2.2% validation), and only 0.2% of E. faecium isolates were identified as truly resistant. The most common errors were: 1) species misidentification (28.0%); 2) incorrect susceptibility results (65.6%); and 3) mixed cultures (4.3%) tested by participants. Overall, quinupristin-dalfopristin was consistently active (> or = 90% susceptible) against major Gram-positive pathogens in North America, regardless of resistance patterns to other drug classes and geographic location of their isolation.
R N Jones; C H Ballow; D J Biedenbach; J A Deinhart; J J Schentag
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Publication Detail:
Type:  Journal Article; Multicenter Study; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Diagnostic microbiology and infectious disease     Volume:  31     ISSN:  0732-8893     ISO Abbreviation:  Diagn. Microbiol. Infect. Dis.     Publication Date:  1998 Jul 
Date Detail:
Created Date:  1998-08-27     Completed Date:  1998-08-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8305899     Medline TA:  Diagn Microbiol Infect Dis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  437-51     Citation Subset:  IM    
Medical Microbiology Division, University of Iowa College of Medicine, Iowa City 52242, USA.
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MeSH Terms
Academic Medical Centers / statistics & numerical data*
Anti-Bacterial Agents / pharmacology*
Drug Resistance, Microbial
Gram-Positive Bacteria / drug effects*,  isolation & purification
Microbial Sensitivity Tests
Species Specificity
United States
Virginiamycin / pharmacology*
Reg. No./Substance:
0/Anti-Bacterial Agents; 11006-76-1/Virginiamycin; 126602-89-9/quinupristin-dalfopristin

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