Intensive Reprocessing of Reusable Bronchoscopes Can Reduce the False Positive Rate of Xpert MTB/RIF Caused by Nucleic Acid Residue

Background/purpose: Tuberculosis remains a leading cause of infectious death worldwide, The potential for nucleic acid residue on bronchoscopes to cause false positive results in molecular diagnostic methods and subsequently lead to tuberculosis misdiagnosis has long perplexed clinical.

Methods: We utilized Xpert MTB/RIF to analyze the liquid collected after bronchoscope washing, employed by patients either with or without active pulmonary tuberculosis, and subjected to standard reprocessing (SR) or intensive reprocessing (IR) procedures. The IR procedure included specialized training and the provision of patient information to cleaning staff before the SR procedure, and repeated washing and suction of the bronchoscope with sterilized water post SR procedure.

Results: 55 participants enrolled in the study were divided into three groups: SR group (n = 28), IR group(n = 14), and the control group(n = 13). Among the 55 enrolled patients, neither Mycobacterium tuberculosis nor contamination was detected by MIGT 960 liquid culture in the washing liquid. The positive rate of MTB/RIF in the SR group (12/28) was significantly higher than that in the IR group (1/14), with a statistically significant difference observed between them (42.86 % vs. 7.14 %, P=0.018).

Conclusions: Nucleic acid residue on reusable bronchoscopes cleaned via the SR procedure was found to potentially cause false positives in MTB/RIF tests. Reprocessing bronchoscopes via the IR procedure was effective in significantly reducing nucleic acid residue, although complete elimination was not achieved.