Increasing Linezolid-resistant Enterococcus in a Children's Hospital

Area of Science:

• Antimicrobial resistance
• Infectious diseases
• Clinical microbiology

Background:

• Linezolid is a critical antibiotic for treating infections caused by multidrug-resistant Gram-positive bacteria.
• Emergence of linezolid resistance is a growing concern in clinical settings.
• Enterococcus species are common causes of nosocomial infections and can develop resistance to antibiotics.

Purpose of the Study:

• To investigate trends in linezolid susceptibility among Enterococcus isolates over a defined period.
• To explore potential associations between linezolid usage patterns and the prevalence of nonsusceptible isolates.
• To identify contributing factors, including patient exposure and potential transmission routes, for reduced linezolid susceptibility.

Main Methods:

• Retrospective analysis of Enterococcus isolates collected between 2007 and 2014.
• Antimicrobial susceptibility testing to determine linezolid resistance.
• Review of patient data to assess linezolid exposure history and identify potential nosocomial transmission.

Main Results:

• A significant reduction in linezolid susceptibility was observed in Enterococcus isolates, decreasing from 98% in 2007 to 46% in 2014.
• A five-fold increase in linezolid utilization was recorded during the study period.
• The majority of patients harboring linezolid-nonsusceptible isolates had no documented prior exposure to linezolid.

Conclusions:

• The rise in linezolid-nonsusceptible Enterococcus isolates is a significant clinical concern.
• While increased linezolid use is noted, direct patient exposure does not fully explain the observed resistance trends.
• Nosocomial transmission of linezolid-nonsusceptible Enterococcus strains is a likely contributing factor requiring further investigation and control measures.