Abstract：
BACKGROUND: Abdominal tuberculosis (TB) is a common epitome of extrapulmonary TB (EPTB), wherein peritoneal and intestinal TB are the most prevalent forms. Diagnosis of abdominal TB is a daunting challenge owing to variable anatomical locations, paucibacillary nature of specimens and atypical clinical presentations that mimic other abdominal diseases, such as Crohn\'s disease and malignancies. In this review, we made a comprehensive study on the diagnosis of abdominal TB.
METHODS: Various modalities employed for abdominal TB diagnosis include clinical features, imaging, bacteriological tests (smear/culture), histopathological/cytological observations, interferon-gamma release assays and nucleic acid amplification tests (NAATs). Among NAATs, loop-mediated isothermal amplification assay, PCR, multiplex-PCR, nested PCR, real-time PCR and GeneXpert® MTB/RIF were discussed. Identification of circulating Mycobacterium tuberculosis cell-free DNA by real-time PCR within ascitic fluids is another useful approach.
CONCLUSIONS: Several novel molecular/immunological methods, such as GeneXpert Ultra, aptamer-linked immobilized sorbent assay, immuno-PCR (I-PCR) and nanoparticle-based I-PCR have recently been developed for detecting pulmonary TB and several EPTB types, which may also be explored for abdominal TB diagnosis. Precise and prompt diagnosis of abdominal TB may initiate an early therapy so as to reduce the complications, i.e. abdominal pain, ascites, abdominal distension, intestinal obstruction/perforation, etc., and avoid surgical involvement.Plain Language SummaryAbdominal tuberculosis (TB) is a manifestation of extrapulmonary TB (EPTB), where peritoneal and intestinal TB are two major forms. Diagnosis of abdominal TB is difficult owing to low bacterial load present in clinical samples and non-specific clinical presentations as it mimics other diseases such as inflammatory bowel diseases, abdominal malignancies, etc. Bacteriological tests (smear/culture) almost fail owing to poor sensitivities and it is not always possible to get representative tissue samples for histopathological and cytological observations. In recent years, molecular tests i.e. nucleic acid amplification tests (NAATs), such as PCR/multiplex-PCR (M-PCR), nested PCR and GeneXpert are widely employed. Markedly, PCR/M-PCR and nested PCR exhibited reasonable good sensitivities/specificities, while GeneXpert revealed low sensitivity in most of the studies but high specificity, thus it could assist in differential diagnosis of intestinal TB and Crohn\'s disease. Further, novel molecular/immunological tests employed for pulmonary TB and other EPTB types were described and those tests can also be utilized to diagnose abdominal TB. Reliable and rapid diagnosis of abdominal TB would initiate an early start of anti-tubercular therapy and reduce the severe complications.
METHODS: Various modalities employed for abdominal TB diagnosis include clinical features, imaging, bacteriological tests (smear/culture), histopathological/cytological observations, interferon-gamma release assays and nucleic acid amplification tests (NAATs). Among NAATs, loop-mediated isothermal amplification assay, PCR, multiplex-PCR, nested PCR, real-time PCR and GeneXpert® MTB/RIF were discussed. Identification of circulating Mycobacterium tuberculosis cell-free DNA by real-time PCR within ascitic fluids is another useful approach.
CONCLUSIONS: Several novel molecular/immunological methods, such as GeneXpert Ultra, aptamer-linked immobilized sorbent assay, immuno-PCR (I-PCR) and nanoparticle-based I-PCR have recently been developed for detecting pulmonary TB and several EPTB types, which may also be explored for abdominal TB diagnosis. Precise and prompt diagnosis of abdominal TB may initiate an early therapy so as to reduce the complications, i.e. abdominal pain, ascites, abdominal distension, intestinal obstruction/perforation, etc., and avoid surgical involvement.Plain Language SummaryAbdominal tuberculosis (TB) is a manifestation of extrapulmonary TB (EPTB), where peritoneal and intestinal TB are two major forms. Diagnosis of abdominal TB is difficult owing to low bacterial load present in clinical samples and non-specific clinical presentations as it mimics other diseases such as inflammatory bowel diseases, abdominal malignancies, etc. Bacteriological tests (smear/culture) almost fail owing to poor sensitivities and it is not always possible to get representative tissue samples for histopathological and cytological observations. In recent years, molecular tests i.e. nucleic acid amplification tests (NAATs), such as PCR/multiplex-PCR (M-PCR), nested PCR and GeneXpert are widely employed. Markedly, PCR/M-PCR and nested PCR exhibited reasonable good sensitivities/specificities, while GeneXpert revealed low sensitivity in most of the studies but high specificity, thus it could assist in differential diagnosis of intestinal TB and Crohn\'s disease. Further, novel molecular/immunological tests employed for pulmonary TB and other EPTB types were described and those tests can also be utilized to diagnose abdominal TB. Reliable and rapid diagnosis of abdominal TB would initiate an early start of anti-tubercular therapy and reduce the severe complications.
摘要：
背景：腹部结核（TB）是肺外结核（EPTB）的常见缩影，其中腹膜和肠TB是最普遍的形式。腹部结核的诊断是一个艰巨的挑战，由于不同的解剖位置，标本的小杆菌性质和模拟其他腹部疾病的非典型临床表现，如克罗恩病和恶性肿瘤。在这次审查中,我们对腹部结核的诊断进行了全面的研究。
方法：用于腹部结核病诊断的各种方式包括临床特征，成像,细菌学测试（涂片/培养），组织病理学/细胞学观察，干扰素-γ释放试验和核酸扩增试验（NAAT）。在NAAT中，环介导等温扩增试验,PCR,多重PCR，巢式PCR，实时PCR和GeneXpert®MTB/RIF进行了讨论。通过实时PCR在腹水中鉴定循环结核分枝杆菌无细胞DNA是另一种有用的方法。
结论：几种新的分子/免疫学方法，比如GeneXpertUltra,适体连接的固定化吸附剂测定，免疫PCR（I-PCR）和基于纳米颗粒的I-PCR最近已被开发用于检测肺结核和几种EPTB类型，这也可以探索腹部结核病的诊断。腹部结核的准确和及时的诊断可以开始早期治疗，以减少并发症。即腹痛,腹水,腹胀,肠梗阻/穿孔,等。,避免手术参与。腹部结核（TB）是肺外结核（EPTB）的一种表现，其中腹膜和肠道结核是两种主要形式。由于临床样本中存在低细菌载量和非特异性临床表现，腹部结核病的诊断很困难，因为它模拟了其他疾病，例如炎症性肠病。腹部恶性肿瘤,等。细菌学测试（涂片/培养）几乎由于敏感性差而失败，并且并不总是可能获得代表性的组织样品进行组织病理学和细胞学观察。近年来,分子测试，即核酸扩增测试(NAAT)，如PCR/多重PCR（M-PCR），巢式PCR和GeneXpert被广泛使用。很明显，PCR/M-PCR和巢式PCR表现出合理的良好敏感性/特异性，虽然GeneXpert在大多数研究中显示灵敏度低，但特异性高，从而有助于肠结核和克罗恩病的鉴别诊断。Further,描述了用于肺结核和其他EPTB类型的新型分子/免疫学测试，这些测试也可用于诊断腹部TB。腹部结核的可靠和快速诊断将启动抗结核治疗的早期开始，并减少严重的并发症。
方法：用于腹部结核病诊断的各种方式包括临床特征，成像,细菌学测试（涂片/培养），组织病理学/细胞学观察，干扰素-γ释放试验和核酸扩增试验（NAAT）。在NAAT中，环介导等温扩增试验,PCR,多重PCR，巢式PCR，实时PCR和GeneXpert®MTB/RIF进行了讨论。通过实时PCR在腹水中鉴定循环结核分枝杆菌无细胞DNA是另一种有用的方法。
结论：几种新的分子/免疫学方法，比如GeneXpertUltra,适体连接的固定化吸附剂测定，免疫PCR（I-PCR）和基于纳米颗粒的I-PCR最近已被开发用于检测肺结核和几种EPTB类型，这也可以探索腹部结核病的诊断。腹部结核的准确和及时的诊断可以开始早期治疗，以减少并发症。即腹痛,腹水,腹胀,肠梗阻/穿孔,等。,避免手术参与。腹部结核（TB）是肺外结核（EPTB）的一种表现，其中腹膜和肠道结核是两种主要形式。由于临床样本中存在低细菌载量和非特异性临床表现，腹部结核病的诊断很困难，因为它模拟了其他疾病，例如炎症性肠病。腹部恶性肿瘤,等。细菌学测试（涂片/培养）几乎由于敏感性差而失败，并且并不总是可能获得代表性的组织样品进行组织病理学和细胞学观察。近年来,分子测试，即核酸扩增测试(NAAT)，如PCR/多重PCR（M-PCR），巢式PCR和GeneXpert被广泛使用。很明显，PCR/M-PCR和巢式PCR表现出合理的良好敏感性/特异性，虽然GeneXpert在大多数研究中显示灵敏度低，但特异性高，从而有助于肠结核和克罗恩病的鉴别诊断。Further,描述了用于肺结核和其他EPTB类型的新型分子/免疫学测试，这些测试也可用于诊断腹部TB。腹部结核的可靠和快速诊断将启动抗结核治疗的早期开始，并减少严重的并发症。
