Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study

Eur J Clin Microbiol Infect Dis. 2024 May;43(5):841-851. doi: 10.1007/s10096-024-04790-2. Epub 2024 Feb 27.

Abstract

Purpose: Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients.

Methods: We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes.

Results: Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia.

Conclusions: The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

Keywords: Staphylococcus aureus bacteraemia; Complicated bacteraemia; Metastatic infection; Methicillin-resistance; Risk stratification.

Publication types

  • Multicenter Study
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use
  • Bacteremia* / diagnosis
  • Bacteremia* / drug therapy
  • Bacteremia* / microbiology
  • Bacteremia* / mortality
  • Female
  • Humans
  • Male
  • Methicillin-Resistant Staphylococcus aureus* / isolation & purification
  • Middle Aged
  • Prospective Studies
  • Retrospective Studies
  • Risk Assessment
  • Risk Factors
  • Staphylococcal Infections* / diagnosis
  • Staphylococcal Infections* / drug therapy
  • Staphylococcal Infections* / microbiology
  • Staphylococcal Infections* / mortality