Chaudhary Jyoti, Chawla Divjot Singh, Gupta Veenu, Singh Akashdeep, Aggarwal Manisha
Department of Microbiology, Dayanand Medical College and Hospital, Ludhiana, Punjab, India.
Department of Medicine, Dayanand Medical College and Hospital, Ludhiana, Punjab, India.
Int J Appl Basic Med Res. 2023 Oct-Dec;13(4):224-229. doi: 10.4103/ijabmr.ijabmr_348_23. Epub 2023 Dec 8.
Xpert Ultra (Cepheid, USA) is recently introduced with an extra category of trace-positive results and higher sensitivity for tuberculosis (TB) diagnosis.
The objective of the study was to assess the diagnostic accuracy of Xpert Ultra for extrapulmonary samples using culture and composite reference standard (CRS) as the gold standard.
In a 1-year (March 2021-22) prospective observational study, samples of suspected extrapulmonary TB (EPTB) patients were subjected to Ziehl-Neelsen staining, culture, and Xpert Ultra (Cepheid, Sunnyvale, CA) tests. Relevant clinical and treatment information was noted. The diagnostic accuracy of Xpert Ultra compared with culture and CRS was calculated.
Out of 1720 suspected patients of EPTB, 223 (13%), predominantly males 135 (60%), with a mean age of 41.46 ± 19.81 years, were diagnosed as TB positive following CRS criteria. The maximum cases were of pleural TB (35.4%), followed by central nervous system TB (17.9%), gastrointestinal TB (17.5%), and lymph node TB (12.1%). Of all samples, 150 (8.7%) were microbiologically confirmed, including 141 detected by Xpert ultra, 67 culture positive, and only 16 smear positive. Among the Xpert Ultra-positive samples, 35 showed trace results, including six false-positive results. Considering culture and CRS as the gold standard, the sensitivity (86.57%, 59.64%) and specificity (94.98%, 99.47%) of Xpert Ultra were calculated, respectively. Rifampicin resistance was detected in 1 (0.70%) sample.
Diagnosis of EPTB is a challenge and Xpert Ultra may detect TB at a very early stage. However, it is essential to rule out false-positive results. Additional studies are needed on Xpert Ultra to interpret trace results better.
Xpert Ultra（美国赛沛公司）最近推出，具有额外的微量阳性结果类别，对结核病（TB）诊断具有更高的灵敏度。
本研究的目的是使用培养和综合参考标准（CRS）作为金标准，评估Xpert Ultra对肺外样本的诊断准确性。
在一项为期1年（2021年3月至2022年）的前瞻性观察研究中，对疑似肺外结核（EPTB）患者的样本进行萋-尼染色、培养和Xpert Ultra（美国赛沛公司，加利福尼亚州桑尼维尔）检测。记录相关的临床和治疗信息。计算Xpert Ultra与培养和CRS相比的诊断准确性。
在1720例疑似EPTB患者中，根据CRS标准，223例（13%）被诊断为TB阳性，其中男性占主导，有135例（60%），平均年龄为41.46±19.81岁。病例最多的是胸膜结核（35.4%），其次是中枢神经系统结核（17.9%）、胃肠道结核（17.5%）和淋巴结结核（12.1%）。在所有样本中，150例（8.7%）经微生物学确诊，其中141例通过Xpert Ultra检测到，67例培养阳性，仅16例涂片阳性。在Xpert Ultra阳性样本中，35例显示微量结果，包括6例假阳性结果。分别以培养和CRS作为金标准，计算Xpert Ultra的灵敏度（86.57%，59.64%）和特异性（94.98%，99.47%）。在1份样本（0.70%）中检测到利福平耐药。
EPTB的诊断具有挑战性，Xpert Ultra可能在非常早期阶段检测到TB。然而，排除假阳性结果至关重要。需要对Xpert Ultra进行更多研究以更好地解释微量结果。
