Influencing factors and benefits of repeated sampling for mycobacterial culture: A real-world study.

Abstract

Background: Bacterial culture plays a crucial role in diagnosing Mycobacterium-induced infections, and repeated sampling significantly improves positive rates in both culture and microscopy tests. However, the factors influencing repeated sampling and the benefits across different patient subpopulations remain unclear.

Methods: This retrospective study included patients suspected of respiratory-tract infections at a tertiary hospital between January 2010 and December 2023. Data on sampling frequency, culture results, clinical features, radiological examinations, and laboratory tests were extracted from the clinical records database.

Results: Of the 16,930 cases, 6.2% (1,047/16,930) had repeated specimens, which yielded a higher positivity rate (23.6%) than single samples (14.8%, P < 0.001). Repeated sampling was more common among patients with positive acid-fast bacilli (AFB), or T. spot assay results, or pulmonary cavities than those with negative results or without pulmonary cavities. However, repeated sampling did not significantly increase culture positivity in patients with positive AFB (P = 0.436), Gene Xpert (P = 0.688), or T. spot (P = 0.841) assay results, or chronic obstructive pulmonary disease (P = 0.269).

Conclusion: Repeated sampling is influenced by clinical features and laboratory findings. Although repeated sampling may enhance mycobacterial culture detection rates, its benefit appears limited in certain patient groups.