Kasa Tom Sharon, Welch Henry, Kilalang Cornelia, Tefuarani Nakapi, Vince John, Lavu Evelyn, Johnson Karen, Magaye Ruth, Duke Trevor
a School of Medicine and Health Science , University of Papua New Guinea , Port Moresby , Papua New Guinea.
b Port Moresby General Hospital , Port Moresby , Papua New Guinea.
Paediatr Int Child Health. 2018 May;38(2):97-105. doi: 10.1080/20469047.2017.1319898. Epub 2017 May 11.
The Gene Xpert MTB/ RIF assay (Xpert) is used for rapid, simultaneous detection of Mycobacterium tuberculosis (MTB) and rifampicin resistance. This study examined the accuracy of Xpert in children with suspected pulmonary tuberculosis (PTB).
Children admitted to Port Moresby General Hospital with suspected PTB were prospectively enrolled between September 2014 and March 2015. They were classified into probable, possible and TB-unlikely groups. Sputum or gastric aspirates were tested by Xpert and smear microscopy; mycobacterial culture was undertaken on a subset. Children were diagnosed with TB on the basis of standard criteria which were used as the primary reference standard. Xpert, smear for acid-fast bacilli (AFB) and the Edwards TB score were compared with the primary reference standard.
A total of 93 children ≤14 years with suspected PTB were enrolled; 67 (72%) were classified as probable, 21 (22%) possible and 5 (5.4%) TB-unlikely. Eighty were treated for TB based on the primary reference standard. Xpert was positive in 26/93 (28%) MTB cases overall, including 22/67 (33%) with probable TB and 4/21 (19%) with possible TB. Three (13%) samples identified rifampicin resistance. Xpert confirmed more cases of TB than AFB smear (26 vs 13, p = 0.019). The sensitivity of Xpert, AFB smear and an Edwards TB score of ≥7 was 31% (25/80), 16% (13/80) and 90% (72/80), respectively, and the specificity was 92% (12/13), 100% (13/13) and 31% (4/13), respectively, when compared with the primary reference standard.
Xpert sensitivity is sub-optimal and cannot be relied upon for diagnosing TB, although a positive result is confirmatory. A detailed history and examination, standardised clinical criteria, radiographs and available tests remain the most appropriate way of diagnosing TB in children in resource-limited countries. Xpert helps confirm PTB better than AFB smear, and identifies rifampicin resistance. Practical guidelines should be used to identify children who will benefit from an Xpert assay.
Gene Xpert MTB/RIF检测（Xpert）用于快速、同时检测结核分枝杆菌（MTB）和利福平耐药性。本研究考察了Xpert在疑似肺结核（PTB）儿童中的准确性。
2014年9月至2015年3月期间，前瞻性纳入莫尔斯比港总医院收治的疑似PTB儿童。他们被分为很可能、可能和不太可能患结核病组。痰液或胃抽吸物采用Xpert和涂片显微镜检查；对一部分样本进行分枝杆菌培养。根据标准标准诊断儿童结核病，该标准用作主要参考标准。将Xpert、抗酸杆菌（AFB）涂片和爱德华兹结核病评分与主要参考标准进行比较。
共纳入93名≤14岁的疑似PTB儿童；67名（72%）被归类为很可能，21名（22%）可能，5名（5.4%）不太可能。根据主要参考标准，80名儿童接受了结核病治疗。总体上，Xpert在93例MTB病例中有26例（28%）呈阳性，包括67例很可能患结核病的儿童中有22例（33%），21例可能患结核病的儿童中有4例（19%）。3份样本（13%）检测出利福平耐药。Xpert确诊的结核病病例比AFB涂片更多（26例对13例，p = 0.019）。与主要参考标准相比，Xpert、AFB涂片和爱德华兹结核病评分≥7时的敏感性分别为31%（25/80）、16%（13/80）和90%（72/80），特异性分别为92%（12/13）、100%（13/13）和31%（4/13）。
Xpert的敏感性欠佳，不能依靠其诊断结核病，不过阳性结果具有确诊意义。详细的病史和检查、标准化的临床标准、X光片和现有检测方法仍然是资源有限国家诊断儿童结核病的最合适方法。Xpert比AFB涂片能更好地确诊PTB，并能检测出利福平耐药性。应使用实用指南来确定能从Xpert检测中受益的儿童。
