Impact of psm-mec in the mobile genetic element on the clinical characteristics and outcome of SCCmec-II methicillin-resistant Staphylococcus aureus bacteraemia in Japan

Tetsuji Aoyagi, C. Kaito, K. Sekimizu, Y. Omae, Y. Saito, H. Mao, S. Inomata, M. Hatta, S. Endo, H. Kanamori, Y. Gu, K. Tokuda, H. Yano, M. Kitagawa, M. Kaku

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13 Citations (Scopus)

Abstract

Over-expression of alpha-phenol-soluble modulins (PSMs) results in high virulence of community-associated methicillin-resistant Staphylococcus aureus (MRSA). The psm-mec gene, located in the mobile genetic element SCCmec-II, suppresses PSMαs production. Fifty-two patients with MRSA bacteraemia were enrolled. MRSA isolates were evaluated with regard to the psm-mec gene sequence, bacterial virulence, and the minimum inhibitory concentration (MIC) of vancomycin and teicoplanin. Fifty-one MRSA isolates were classified as SCCmec-II, and 10 had one point mutation in the psm-mec promoter. We compared clinical characteristics and outcomes between mutant MRSA and wild-type MRSA. Production of PSMα3 in mutant MRSA was significantly increased, but biofilm formation was suppressed. Wild-type MRSA caused more catheter-related bloodstream infections (30/41 vs. 3/10, p 0.0028), whereas mutant MRSA formed more deep abscesses (4/10 vs. 3/41, p 0.035). Bacteraemia caused by mutant MRSA was associated with reduced 30-day mortality (1/10 vs. 13/41, p 0.25), although this difference was not significant. The MIC90 of teicoplanin was higher for wild-type MRSA (1.5 mg/L vs. 1 mg/L), but the MIC of vancomycin was not different between the two groups. The 30-day mortality of MRSA with a high MIC of teicoplanin (≥1.5 mg/L) was higher than that of strains with a lower MIC (≤0.75 mg/L) (6/10 vs. 6/33, p 0.017). Mutation of the psm-mec promoter contributes to virulence of SCCmec-II MRSA, and the product of psm-mec may determine the clinical characteristics of bacteraemia caused by SCCmec-II MRSA, but it does not affect mortality.

Original languageEnglish
Pages (from-to)912-919
Number of pages8
JournalClinical Microbiology and Infection
Volume20
Issue number9
DOIs
Publication statusPublished - Sep 1 2014
Externally publishedYes

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Keywords

  • Clinical characteristics
  • MRSA
  • Phenol-soluble modulins
  • Teicoplanin
  • Vancomycin
  • psm-mec mutation

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

Cite this

Aoyagi, T., Kaito, C., Sekimizu, K., Omae, Y., Saito, Y., Mao, H., Inomata, S., Hatta, M., Endo, S., Kanamori, H., Gu, Y., Tokuda, K., Yano, H., Kitagawa, M., & Kaku, M. (2014). Impact of psm-mec in the mobile genetic element on the clinical characteristics and outcome of SCCmec-II methicillin-resistant Staphylococcus aureus bacteraemia in Japan. Clinical Microbiology and Infection, 20(9), 912-919. https://doi.org/10.1111/1469-0691.12575