Department of Laboratory Medicine, Shanghai Geriatric Medical Center, Zhongshan Hospital Minhang Meilong, Fudan University, Shanghai, China.
Department of Laboratory Medicine, Shanghai Public Health Clinical Center, Shanghai, China.
BMC Infect Dis. 2024 Aug 1;24(1):770. doi: 10.1186/s12879-024-09684-4.
The GeneXpert MTB/RIF (Xpert) assay is a widely used technology for detecting Mycobacterium tuberculosis (MTB) in clinical samples. However, the study on the failure of the Xpert assay during routine implementation and its potential solutions is limited.
We retrospectively analyzed the records of unsuccessful tests in the Xpert and the GeneXpert MTB/RIF Ultra (Ultra) assays between April 2017 and April 2021 at the Shanghai Public Health Clinical Center. To further investigate the effect of prolonged preprocessing on clinical sputum, an additional 120 sputum samples were collected for Xpert testing after 15 min, 3 h, and 6 h preprocessing. The analysis was performed by SPSS version 19.0 software.
A total of 11,314 test records were analyzed, of which 268 (2.37%) had unsuccessful test results. Among these, 221 (1.95%) were reported as "Error", 43 (0.38%) as "Invalid", and 4 (0.04%) as "No result". The most common clinical specimen for Xpert tests was sputum, accounting for 114 (2.17%) unsuccessful tests. The failure rate of urine specimens was lower than that of sputum (OR = 0.12, 95% CI: 0.02-0.88, χ = 6.22, p = 0.021). In contrast, the failure rate of stool specimens was approximately twice as high as that of sputum (OR = 1.93, 95% CI: 1.09-3.40, χ = 5.35, p = 0.014). In the prolonged preprocessing experiment, 102 cases (85%) yielded consistent results in Xpert tests. Furthermore, 7 cases (5.83%) detected an increase in MTB load, 8 cases (6.67%) detected a decrease in MTB load, and 3 cases (2.5%) yielded incongruent results in MTB and rifampicin resistance detection.
The primary cause of unsuccessful tests in the Xpert assay was reported as "Error". Despite varying failure rates depending on the samples, the Xpert assay can be applied to extrapulmonary samples. For paucibacillary specimens, retesting the remaining preprocessed mixture should be carefully considered.
GeneXpert MTB/RIF（Xpert）检测是一种广泛用于检测临床样本中结核分枝杆菌（MTB）的技术。然而，关于 Xpert 检测在常规实施过程中的失败及其潜在解决方案的研究是有限的。
我们回顾性分析了 2017 年 4 月至 2021 年 4 月上海公共卫生临床中心 Xpert 和 GeneXpert MTB/RIF Ultra（Ultra）检测中未成功的检测记录。为了进一步研究延长预处理对临床痰液的影响，我们对 120 例预处理 15 分钟、3 小时和 6 小时后的痰液样本进行了 Xpert 检测。分析使用 SPSS 19.0 软件进行。
共分析了 11314 个检测记录，其中 268 个（2.37%）检测结果未成功。其中，221 个（1.95%）报告为“Error”，43 个（0.38%）为“Invalid”，4 个（0.04%）为“无结果”。Xpert 检测最常见的临床标本是痰液，占 114 例（2.17%）未成功检测。尿液标本的失败率低于痰液（OR=0.12，95%CI：0.02-0.88，χ²=6.22，p=0.021）。相比之下，粪便标本的失败率是痰液的近两倍（OR=1.93，95%CI：1.09-3.40，χ²=5.35，p=0.014）。在延长预处理实验中，102 例（85%）Xpert 检测结果一致。此外，7 例（5.83%）检测到 MTB 载量增加，8 例（6.67%）检测到 MTB 载量减少，3 例（2.5%）MTB 和利福平耐药检测结果不一致。
Xpert 检测未成功的主要原因报告为“Error”。尽管不同样本的失败率不同，但 Xpert 检测可应用于肺外样本。对于少菌标本，应慎重考虑重新检测剩余预处理混合物。
