Simultaneous antibiotic levels in "breakthrough" gram-negative rod bacteremia

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Pharmacology

Background:

• Gram-negative rod bacteremia is a significant cause of hospital-acquired infections.
• Antibiotic resistance and treatment failure remain critical challenges in managing bacteremia.
• Breakthrough bacteremia, occurring despite antibiotic therapy, requires careful investigation.

Purpose of the Study:

• To investigate the characteristics and outcomes of breakthrough gram-negative rod bacteremia.
• To identify factors associated with treatment failure in patients with bacteremia receiving antibiotics.
• To analyze the relationship between antibiotic levels and treatment efficacy.

Main Methods:

• Retrospective analysis of 237 cases of gram-negative rod bacteremia at UCLA Medical Center.
• Assessment of antibiotic susceptibility testing (disc diffusion) and plasma antibiotic levels.
• Correlation of clinical data, including timing of sepsis, causative organism, antibiotic therapy, and treatment outcomes.

Main Results:

• 52% of breakthrough bacteremias occurred despite antibiotics inhibiting the organism in vitro.
• Subinhibitory antibiotic levels were detected in half of the plasma samples from patients with breakthrough bacteremia.
• Early-onset sepsis was often linked to antibiotic-sensitive Escherichia coli and inadequate levels, while late-onset sepsis involved resistant strains and other complications.

Conclusions:

• Inadequate antibiotic levels contribute to treatment failure in early breakthrough bacteremia.
• Late-onset breakthrough bacteremia failure is associated with factors like inadequate drainage and compromised host defenses.
• Optimizing antibiotic therapy and addressing underlying conditions are vital for improving outcomes in gram-negative rod bacteremia.