Linezolid-resistant staphylococcal bacteraemia: A multicentre case-case-control study in Italy

Area of Science:

• Infectious Diseases
• Microbiology
• Clinical Medicine

Background:

• Linezolid is a crucial antibiotic for treating serious Gram-positive bacterial infections.
• Emergence of linezolid resistance in Staphylococcus species poses a significant threat to patient care.
• Understanding the characteristics and risk factors for linezolid-resistant infections is vital for effective management.

Purpose of the Study:

• To analyze the clinical features and risk factors associated with linezolid-resistant (LIN-R) Staphylococcus bloodstream infections.
• To compare LIN-R infections with linezolid-susceptible (LIN-S) infections and identify differentiating factors.
• To investigate the molecular mechanisms of linezolid resistance in Staphylococcus strains.

Main Methods:

• Retrospective case-case-control study involving patients from three Italian teaching hospitals.
• Comparison of patients with LIN-R Staphylococcus, LIN-S Staphylococcus, and control groups.
• Molecular typing and genetic analysis of LIN-R Staphylococcus strains to identify resistance mechanisms.

Main Results:

• Central venous catheters were a more frequent source of infection in the LIN-R group compared to the LIN-S group.
• Patients with LIN-R infections had a higher 30-day mortality rate.
• Independent risk factors for LIN-R strains included previous linezolid therapy, prolonged antibiotic use, and recent hospitalisation.
• The G2576T mutation in 23S rRNA was the primary resistance mechanism.

Conclusions:

• Linezolid-resistant Staphylococcus strains are associated with severe clinical conditions and poor patient outcomes.
• Effective infection control measures are essential to prevent the spread of these resistant infections.
• Identifying and managing risk factors like prior antibiotic exposure can help mitigate the emergence of linezolid resistance.