In vitro study of the antimicrobial effects of radiological contrast agents used in arthrography

Area of Science:

• Orthopedics
• Microbiology
• Radiology

Background:

• Aspiration arthrography with iodinated contrast media aids in diagnosing joint prosthesis complications and septic arthritis.
• Concerns exist that contrast media may cause false-negative microbial cultures due to iodine's potential bactericidal effects.
• Previous reports on this interference have been inconclusive.

Purpose of the Study:

• To investigate the impact of older high-osmolar and current low-osmolar iodinated contrast media on microbial growth.
• To determine if these agents affect the accuracy of synovial fluid cultures for diagnosing joint infections.

Main Methods:

• Ten clinically relevant microorganisms were tested against five contrast media.
• Disc diffusion and time-killing curve assays were employed using varying microbial inocula.
• Incubation was performed in undiluted contrast media to simulate clinical conditions.

Main Results:

• Bactericidal effects were minimal, observed only with low inocula of specific bacteria (E. coli, P. aeruginosa) in an older ionic contrast agent (ioxithalamate).
• Current low and iso-osmolar iodinated contrast media did not impede the growth of tested microorganisms.
• The risk of contrast media-induced false-negative cultures appears negligible with contemporary agents.

Conclusions:

• Modern low and iso-osmolar iodinated contrast media are suitable for aspiration arthrography without compromising synovial fluid culture results.
• These agents do not impede microbial growth, supporting their continued use in diagnosing septic arthritis and prosthesis loosening.
• Further research should explore other causes of false-negative cultures and methods to enhance microbial recovery.