en
Scientific article
Case report
English

First detection of an invasive Staphylococcus aureus strain (D958) with reduced susceptibility to glycopeptides in Saudi Arabia

Published inJournal of clinical microbiology, vol. 48, no. 6, p. 2199-2204
Publication date2010
Abstract

Strain D958, a methicillin-resistant Staphylococcus aureus strain with reduced susceptibility to vancomycin, was isolated from a 69-year-old Saudi male patient presenting with severe sepsis immediately after admission. Despite high serum levels of vancomycin, the same S. aureus strain was isolated from five blood culture sets during 1 week. Treatment failure under therapeutic levels of vancomycin prompted us to investigate the resistance profile of this strain in further detail. The MIC values for vancomycin as determined by Etest and microdilution were 3.0 and 2.0 mg/liter, respectively, and remained unchanged during the treatment course. The macro-Etest method showed a MIC of 4 mg/liter. The strain showed liquid vancomycin and lysostaphin MBCs of 2.0 and 5.0 mg/liter, respectively. The isolates were confirmed as heterogeneously vancomycin-intermediate S. aureus (hVISA) by vancomycin population analysis profile. The areas under these curves were similar for Mu3 and D958 for vancomycin and teicoplanin (ratio values were 1 and 1.1 for vancomycin and teicoplanin, respectively). Extensive genotyping and molecular characterization demonstrated that the strain harbored a staphylococcal cassette chromosome mec element (SCCmec) type III cassette and was of sequence type ST241, a single-locus variant of the successful multiresistant clone ST239. Microarray results demonstrated that D958 contained numerous resistance determinants (generally plasmid or phage encoded). These results suggest that this strain is constitutively expressing an altered susceptibility to vancomycin. Further studies are warranted to assess the clonal distribution of such strains displaying reduced susceptibility to vancomycin prior to any antimicrobial therapy.

Keywords
  • Aged
  • Anti-Bacterial Agents/analysis/*pharmacology/therapeutic use
  • Bacterial Typing Techniques
  • Blood/microbiology
  • Chromosomes, Bacterial
  • Cluster Analysis
  • DNA Fingerprinting
  • DNA, Bacterial/genetics
  • Genes, Bacterial
  • Genotype
  • Humans
  • Lysostaphin/pharmacology
  • Male
  • Methicillin-Resistant Staphylococcus aureus/*drug effects/*isolation & purification
  • Microarray Analysis
  • Microbial Sensitivity Tests
  • Microbial Viability/drug effects
  • Plasmids
  • Saudi Arabia
  • Sepsis/*microbiology
  • Serum/chemistry
  • Staphylococcal Infections/*microbiology
  • Teicoplanin/pharmacology
  • Vancomycin/analysis/*pharmacology/therapeutic use
  • *Vancomycin Resistance
Citation (ISO format)
AL-OBEID, S. et al. First detection of an invasive Staphylococcus aureus strain (D958) with reduced susceptibility to glycopeptides in Saudi Arabia. In: Journal of clinical microbiology, 2010, vol. 48, n° 6, p. 2199–2204. doi: 10.1128/JCM.00954-09
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ISSN of the journal0095-1137
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