Pseudobacteremia caused by Clostridium sordellii

Area of Science:

• Microbiology
• Clinical Pathology
• Infectious Diseases

Background:

• Clostridium sordellii, a spore-forming anaerobe, is rarely identified as a human pathogen.
• An unusual rate of positive blood cultures for C. sordellii was observed over a 12-day period.
• Nosocomial bacteremia and contamination of blood culture materials were initially investigated as potential sources.

Purpose of the Study:

• To identify the source of spurious Clostridium sordellii blood culture positivity.
• To determine the cause of pseudobacteremia in a clinical microbiology setting.
• To implement corrective actions and prevent recurrence.

Main Methods:

• Systematic investigation of the blood culture collection and processing workflow.
• Exclusion of patient-related bacteremia and intrinsic contamination of culture media.
• Identification of contaminated thimerosal tincture as the source of C. sordellii.

Main Results:

• Thirteen out of 280 blood cultures (4.6%) yielded positive results for Clostridium sordellii.
• The source was traced to contaminated thimerosal tincture used for swabbing bottle stoppers.
• Pseudobacteremia was confirmed and not related to patient infection.
• Implementation of safeguards eliminated further C. sordellii contamination.

Conclusions:

• Contaminated thimerosal tincture is a potential source of pseudobacteremia with Clostridium sordellii.
• Routine laboratory procedures, even seemingly minor steps, require rigorous quality control.
• Attention to less conspicuous steps in culture material processing is crucial for accurate diagnostic results.