Pathak C M, Bhasin D K, Khanduja K L
Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India.
Trop Gastroenterol. 2004 Oct-Dec;25(4):156-61.
Helicobacter pylori (H. pylori) is the commonest bacterial pathogen found worldwide and more than half the world population aged 40 years and above is colonized with it. The infection rate is >95 % in some African countries. In 1994, the International Agency for Research on cancer classified H. pylori as a class I carcinogen in humans. It causes chronic active gastritis, duodenal and gastric ulcer and gastric malignancy, and is thought to be associated with coronary artery disease, cerebral stroke, vitamin B12 and iron-deficiency anaemia, etc. Therefore, non-invasive test-and-treatment strategies are widely recommended in primary care settings. Conventionally, H. pylori infection can be diagnosed by invasive techniques using an upper gastrointestinal endoscope for obtaining multiple biopsies from different sites of the stomach for RUT, culture, histological examination, polymerase chain reaction (PCR), etc. and by non-invasive tests such as Urea breath test (UBT), stool antigen test and blood serology. At present, 13/14C-UBT is considered the test of choice for confirmation of H. pylori infection. The UBT is based on the principle, that isotopically labelled urea ingested by an H. pylori--infected patient is rapidly hydrolysed by the microbial urease. The released 13/14CO2 is absorbed across the mucous layer to the gastric mucosa and hence, excreted via the systemic circulation in the breath which is collected and measured. The non-hydrolysed urea is excreted completely in the urine within 3-4 days. 13C-UBT being non-radioactive, 13C-UBT can be used in pregnant women and children, and a user's license is not required. There is still no standard protocol accepted and followed internationally for this test. Although the methods are almost similar, various laboratories/clinics use variable tracer doses, test meals, timings and methods for breath collection, and different cut-off values, which make formal validation studies necessary. This review describes the present status of the UBT and its application in the detection of H. pylori infection.
幽门螺杆菌（H. pylori）是全球范围内最常见的细菌病原体，全球40岁及以上人群中超过一半都感染了这种细菌。在一些非洲国家，感染率超过95%。1994年，国际癌症研究机构将幽门螺杆菌列为人类I类致癌物。它会引发慢性活动性胃炎、十二指肠和胃溃疡以及胃癌，还被认为与冠状动脉疾病、脑卒、维生素B12和缺铁性贫血等有关。因此，在基层医疗环境中广泛推荐采用非侵入性检测和治疗策略。传统上，幽门螺杆菌感染可通过侵入性技术诊断，即使用上消化道内窥镜从胃的不同部位获取多个活检样本进行快速尿素酶试验（RUT）、培养、组织学检查、聚合酶链反应（PCR）等，也可通过非侵入性检测，如尿素呼气试验（UBT）、粪便抗原检测和血液血清学检测。目前，13/14C-UBT被认为是确认幽门螺杆菌感染的首选检测方法。尿素呼气试验基于这样的原理：幽门螺杆菌感染患者摄入的同位素标记尿素会被微生物尿素酶迅速水解。释放出的13/14CO2穿过黏液层被胃黏膜吸收，进而通过呼吸经体循环排出，收集并测量呼出的气体。未水解的尿素在3 - 4天内会完全通过尿液排出。13C-UBT无放射性，可用于孕妇和儿童，无需使用许可证。目前该检测在国际上仍没有被广泛接受和遵循的标准方案。尽管方法几乎相似，但不同实验室/诊所使用的示踪剂剂量、试验餐、时间和呼气收集方法各不相同，且截断值也不同，这使得进行正式的验证研究很有必要。本综述描述了尿素呼气试验的现状及其在幽门螺杆菌感染检测中的应用。
