Quality of Sputum Specimen Samples Submitted for Culture and Drug Susceptibility Testing at the National Tuberculosis Reference Laboratory-Uganda, July-October 2013.

Abstract

Setting: The Uganda National Tuberculosis Reference Laboratory (NTRL) in Kampala.

Objective: The proportion of poor quality specimens received for drug susceptibility testing (DST) at the NTRL and factors contributing to poor specimen quality were assessed.

Design: A cross-sectional study was conducted of sputum samples received at the NTRL from patients at high risk for multidrug-resistant tuberculosis (MDR TB) during July-October 2013. Demographic, clinical, and bacteriological data were abstracted from laboratory records. A poor quality sample failed to meet any one of four criteria: ≥3 milliliter (ml) volume, delivered within 72 hours, triple packaged, and non-salivary appearance.

Results: Overall, 365 (64%) of 556 samples were of poor quality; 89 (16%) were not triple packaged, 44 (8%) were <3 mls, 164 (30%) were not delivered on time, and 215 (39%) were salivary in appearance. Poor quality specimens were more likely to be collected during the eighth month of TB treatment (OR = 2.5, CI = 1.2 - 5.1), from the East or Northeast zones (OR = 2.2, CI = 1.1 - 4.8), and from patients who previously defaulted from treatment (OR = 1.9, CI = 1.1 - 3.2).

Conclusion: The majority of sputum samples had poor quality. Additional efforts are needed to improve quality of samples collected at the end of treatment, from East and Northeast zones, and from patients who had previously defaulted.