agr functionality affects clinical outcomes in patients with persistent methicillin-resistant Staphylococcus aureus...

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Epidemiology

Background:

• Methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) can persist despite treatment, leading to poor outcomes.
• Microbiological factors influencing persistent MRSAB (pMRSAB) and associated mortality remain incompletely understood.

Purpose of the Study:

• To identify clinical and microbiological risk factors for in-hospital mortality in patients with pMRSAB.

Main Methods:

• Prospective analysis of 152 pMRSAB cases (MRSAB ≥5 days despite effective antibiotics) from 11 Korean hospitals (2009-2016).
• Microbiological testing included SCCmec type, Spa type, agr type, PVL, PSM-mec genes, vancomycin MIC, vancomycin heteroresistance, and agr functionality.
• Clinical data included comorbidity scores (CCWI, Pitt, SOFA), septic shock, pneumonia, and infection foci.

Main Results:

• Univariable analysis identified CCWI, Pitt bacteremia score, SOFA score, septic shock, pneumonia, agr dysfunction, and vancomycin heteroresistance as mortality-associated factors.
• Bone and joint infections were associated with lower mortality.
• Multivariable analysis revealed CCWI score, Pitt bacteremia score, non-eradicated foci of infection, and agr dysfunction as independent predictors of in-hospital mortality.

Conclusions:

• Accessory gene regulator (agr) dysfunction is an independent risk factor for in-hospital mortality in persistent MRSAB.
• Clinical severity scores and uncontrolled infection sources also significantly contribute to mortality in pMRSAB.