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中國兒童幽門(mén)螺桿菌感染與飲食習慣
| 江驥 北京協(xié)和醫院 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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幽門(mén)螺桿菌（Helicobacter pylori）與幽門(mén)螺桿菌感染 不同國家幽門(mén)螺桿菌感染情況的概述 幽門(mén)螺桿菌感染的途徑和飲食習慣 我國兒童幽門(mén)螺桿菌感染的初步調查 1 方法學(xué)：13C-尿素呼氣試驗（13C-urea Breath test）
原理, 過(guò)程 2 初步流調和結果 北京，山東，江蘇，貴州，廣東，西藏 3 幽門(mén)螺桿菌感染與胃癌的發(fā)生 4 父母幽門(mén)螺桿菌感染與兒童 摘要： 幽門(mén)螺桿菌研究概況 1983年，澳大利亞學(xué)者Warren和Marshall報告，在人胃粘膜活檢組織中分離這種細菌，即幽門(mén)螺桿菌（Helicobacter pylori, HP;原名幽門(mén)彎曲菌 Campylobacterpylori, CP） 并認為該菌可能是慢性胃炎和消化性潰瘍的病原菌。隨后各國學(xué)者相繼進(jìn)行了研究，短短幾年內，大量的研究資料表明，HP是慢性胃炎的主要病因，在消化性潰瘍，特別是十二指腸潰瘍的發(fā)病中可能起重要作用，與非潰瘍性消化不良和胃癌亦有一定關(guān)系，世界衛生組織認定，HP是導致胃癌的頭號因素。 國外的流行病調查結果提示，發(fā)展中國家比發(fā)達國家的感染率高，東方人感染率比西方人高，不少作者認為，這與東方人的飲食習慣有關(guān)（如共餐制，筷子等）。
HP是一種微需氧的革蘭氏陰性細菌，人的胃粘膜是HP的自然定植部位；另外，在Barrett食管，Meckel室和直腸的胃粘膜化生區也可檢出HP。但在正常腸粘膜上皮未能檢出HP定植。HP在電鏡下是一個(gè)小桿菌，長(cháng)約2-3mm,常有1-2彎曲呈S形或弧形，有鞭毛。
（三）HP的傳染途徑
主要為人—人之間的傳播，包括口—口傳播和糞—口傳播。 （四）HP的致病機理
HP能導致疾病的主要原因在于：1）其能產(chǎn)生有害的酶，包括尿素酶；產(chǎn)生氨，氨是細胞毒素，可損害上皮屏障，破壞胃泌素/胃酸反饋體系 2）過(guò)氧化氫酶； 3）HP菌體本身就是一種內毒素，可以刺激免疫系統，引起炎癥。 HP的診斷方法
診斷HP感染的方法數種：其中包括細菌培養、病理學(xué)染色、快速尿素酶試驗、血清免疫學(xué)檢查和同位素呼氣試驗等。前三種方法均需通過(guò)胃鏡來(lái)獲取一定數量的組織標本，故而有一定的創(chuàng )傷和痛苦，此外，由于HP在胃中的生長(cháng)呈斑塊狀分布，在通過(guò)胃鏡活檢時(shí)，即使事實(shí)上存在有HP的感染，但在取標本時(shí)也容易有漏診的可能，特別是近年來(lái)有一些報道發(fā)現這種細菌存在于胃體部，而不僅僅在幽門(mén)部位。故而取標本的不足容易導致假陰性的結果發(fā)生。 細菌培養
活檢組織尿素酶試驗
組織切片染色
血清學(xué)
 門(mén)螺桿菌感染與胃腸疾病關(guān)系的假說(shuō) 13C尿素呼氣試驗
該方法采用了穩定同位素以及質(zhì)譜學(xué)等技術(shù)，準確、特異、快捷。靈敏度和特異性都在95%左右，受檢查者無(wú)痛苦，無(wú)創(chuàng )傷，無(wú)放射性損傷。
2．原理
由于HP具有內源性、特異性的尿素酶，可將尿素分解為NH3和CO2，CO2在小腸上端吸收后進(jìn)入血液循環(huán)并隨呼氣排出。讓受檢查者口服13C標記的尿素后，如果胃中存在HP感染，就可以將13C標記的尿素分解為13C標記的CO2因此，通過(guò)用高精度的氣體同位素比值質(zhì)譜儀（Gas Isotopic Ratio Mass Spectrometer, GIRMS）來(lái)探測呼氣中的13C—CO2即可診斷HP的感染，由于口服的13C-尿素到達胃后呈均勻分布，只要在13C-尿素接觸的部位存在著(zhù)HP感染，就可靈敏地檢測到。
HP的流行病學(xué)
HP感染在世界各地都較為常見(jiàn)，有人估計約半數的人口其胃內有HP定居，人們已接受HP是慢性胃炎的主要病因。胃炎的發(fā)病率與HP的感染率均隨年齡的增長(cháng)而增高。一旦感染HP，多持續終生。在不同地區，不同種族，不同人群或同一人群的不同個(gè)體之間，HP的感染率差別很大，這與衛生習慣和設備有關(guān)。在經(jīng)濟不發(fā)達國家感染率較高，初次感染的年齡早，5歲兒童的感染率已達50%，成人感染率可達90%。在發(fā)達國家，HP的感染率與以往報道的慢性胃炎和消化不良新發(fā)病例的發(fā)病率大致相同，即隨年齡每年增加1-2%，在不同信仰、種族、道德標準和社會(huì )經(jīng)濟地位人群間差別也顯著(zhù)。該菌的傳播主要是人—人之間通過(guò)糞—口或口—口途徑。已有報道在家庭內通過(guò)密切接觸可造成傳播。另外，內鏡檢查也可傳播HP，具有活力的螺旋形HP在河水中至少可存活一周，而球形的HP則可存活一年多，但后者無(wú)致病力。HP的流行病學(xué)模式與甲型肝炎和疫苗預防問(wèn)世前的脊髓灰質(zhì)炎相似，后兩種病均經(jīng)糞—口途徑傳播，流行病學(xué)資料表明，胃粘膜病變與消化性潰瘍和胃癌相關(guān)，初次感染HP年齡較早的人群，胃癌的發(fā)病率也高。北京協(xié)和醫院和國內的有關(guān)單位合作，采用 13C-尿素呼氣試驗，對我國胃癌高發(fā)區和低發(fā)區部分正常兒童（3-12歲）的HP感染情況進(jìn)行了調查，結果如表所示：
表 我國部分地區兒童螺桿菌感染的流行病學(xué)調查結果
Helicobacter Pylori Infection and the Eating Habits of Chinese Children
Jiang Ji
Beijing Union Hospital
l Helicobacter pylori and its infection
l The overview of Helicobacter pylori infection in different countries
l The ways of Helicobacter pylori infection and the eating habits
l Preliminary survey of the Helicobacter pylori infection of children in China
1. Method: 13C-urea Breath test
Principle, procedure
2. Epidemiological study and result
Beijing, Shandong, Jiangsu, Guizhou, Guangdong, Tibet
3. Helicobacter pylori infection and gastric carcinoma
4. The Vertical transmission of Helicobacter pylori between parents and their children
Abstract:
Overview of research on H.P.
HP was separated from human gastric mucosa by Warren and Marshall in Australia in 1983. Extensive research studies have shown that HP is a chief etiological factor of chronic gastritis, and it may also play an essential role in the development of peptic ulcer, especially the duodenal ulcer. In addition, HP may associate with functional dyspepsia and gastric cancer. According to WHO, HP is the top-one etiological factor of gastric cancer.
The results of epidemiological studies indicated that the prevalence of HP infection was higher in developing countries than developed countries. Eastern people had a higher rate of infection than their western counterparts, which may be related to the eating habits of eastern people (e.g. sharing food, using chopstick).
HP is a gram-negative curved or spiral bacterium with a 2-6 Uni-polar sheathed flagella which is originally located in gastric epithelium (include the gastric mateplasiu in Barrett’s esophagus, Meckel’s diverticulum and rectum). It can’t be separated from the normal intestinal epithelium.
3. The transmission route of HP infection
Several ways of transmission from person to person have been confirmed. The predominant route of infection is considered to be vomit-oral in early life. The oral-oral route and the fetal-oral sent are also considered to be possible.
4. The pathogenic mechanism of HP infection
HP is able to colonize because of its adapted motility and its ability to form a neutral microenvironment with urease activity. Adhesions permit adherence to surface cells of the gastric epithelium and damage may be caused by enzymes such as protease, catalase, and etc., on the cytotonic proteins Cag A or Vac A.
The diagnosis of HP infection Non-endoscopic
Serology
13C urea breath test
Endoscopy
Biopsy urease test
Histology
Cell culture
Epidemiology of HP infection
The HP infection is very common worldwide. It is estimated that about half of the population has HP infection in their stomachs. It is believed that HP is the major risk factor for chronic gastritis. The older, the higher the incidence of chronic gastritis and the rate of HP infection. It will last for lifelong if it is infected. The infection rate varies significantly in different regions, races, and populations and between individuals which closely related to personal habit and sanitation equipment. It is more common in developing countries. The infection rate in children aged 5 years and in adults are 50% and 90% respectively. Epidemiological studies showed that the younger the HP infection, the higher the incidence of gastric cancer.
We conducted a survey of HP infection in children aged between 3-12 years in areas with high-prevalent and low-prevalent gastric cancer by using 13C-urea Breath Test.
Epidemiological Studies of HP infections in some areas of China
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