Tuberculosis diagnostics in Fiji: how reliable is culture?

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• Acid-fast bacilli (AFB) smear microscopy and Mycobacterium tuberculosis culture are primary diagnostic methods for tuberculosis (TB).
• TB culture contamination compromises diagnostic accuracy and reliability.

Purpose of the Study:

• To identify factors contributing to TB culture contamination in Fiji.
• To compare the diagnostic performance of TB culture versus microscopy.

Main Methods:

• A retrospective review of TB diagnostic tests performed at the Daulakao Mycobacterium Reference Laboratory (DMRL) in Fiji between 2010 and 2012.
• Analysis of variables including AFB smear results, TB culture results, specimen type and age, referring center, and patient age.

Main Results:

• Out of 5708 specimens, 421 (7.4%) were contaminated, and 2.7% had no or degraded results.
• Moderate agreement (κ = 0.577) was observed between AFB smear and TB culture.
• Culture contamination was associated with increased distance from the DMRL, older specimen age, and operator-related factors.

Conclusions:

• Faster specimen referral and sputum preservation may decrease TB culture contamination rates.
• Implementing liquid culture techniques alongside Ogawa media culture is expected to improve TB diagnostic sensitivity in Fiji.