Blood culture technique: current controversies.

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Diagnostic Laboratory Science

Background:

• Determining optimal blood culture volume and system is crucial for accurate pathogen identification.
• Controversies exist regarding the best practices for blood culture diagnostics.

Purpose of the Study:

• To provide recommendations on optimal blood volume for culture.
• To identify the most suitable blood culture systems for rapid and reliable pathogen detection.

Main Methods:

• Discussion and recommendation of blood culture volumes (10-30 ml per set).
• Evaluation of routine systems (diphasic/anaerobic broths) and alternative systems (infrared Bactec, lysis-centrifugation).
• Consideration of specific patient populations (febrile, immunocompromised, infective endocarditis) and organism types ('difficult organisms').

Main Results:

• Recommends culturing at least 10 ml, ideally up to 30 ml, of blood per set.
• Suggests a routine system with two aerobic diphasic media and one anaerobic broth for 20 ml blood per set, including blind subcultures.
• Proposes the infrared Bactec system as a practical alternative for high-volume laboratories.
• Advocates for lysis-centrifugation systems for isolating difficult organisms.
• Recommends including a non-Liquoid bottle in routine systems to avoid inhibiting sensitive organisms.

Conclusions:

• Optimal blood volume and appropriate culture systems significantly impact the detection of pathogens.
• Laboratory capacity and specific clinical needs should guide the choice of blood culture methodology.
• Careful consideration of media composition, such as avoiding Liquoid, is essential for comprehensive pathogen recovery.