Riordan S M, McIver C J, Walker B M, Duncombe V M, Bolin T D, Thomas M C
Department of Gastroenterology, Prince of Wales Hospital, Sydney, Australia.
Am J Gastroenterol. 1996 Sep;91(9):1795-803.
To i) document the sensitivity and specificity of a combined scintigraphic/lactulose breath hydrogen test for small intestinal bacterial overgrowth and ii) investigate the validity of currently accepted definitions of an abnormal lactulose breath hydrogen test based on "double peaks" in breath hydrogen concentrations.
Twenty-eight subjects were investigated with culture of proximal small intestinal aspirate and a 10-g lactulose breath hydrogen test combined with scintigraphy. Gastroduodenal pH, the presence or absence of gastric bacterial overgrowth, and the in vitro capability of overgrowth flora to ferment lactulose were determined.
Sensitivity (16.7%) and specificity (70.0%) of the lactulose breath hydrogen test alone for small intestinal bacterial overgrowth were poor. Combination with scintigraphy resulted in 100% specificity, because double peaks in serial breath hydrogen concentrations may occur as a result of lactulose fermentation by cecal bacteria. Sensitivity increased to 38.9% with scintigraphy, because a single rise in breath hydrogen concentrations, commencing before the test meal reaches the cecum, may occur in this disorder. Sensitivity remained suboptimal irrespective of the definition of small intestinal bacterial overgrowth used, the nature of the overgrowth flora, favorable luminal pH, the presence of concurrent gastric bacterial overgrowth, or the in vitro ability of the overgrowth flora to ferment lactulose.
Definitions of an abnormal lactulose breath hydrogen test based on the occurrence of double peaks in breath hydrogen concentrations are inappropriate. Not even the addition of scintigraphy renders this test a clinically useful alternative to culture of aspirate for diagnosing small intestinal bacterial overgrowth.
i）记录联合闪烁扫描/乳果糖呼气氢试验对小肠细菌过度生长的敏感性和特异性；ii）研究基于呼气氢浓度“双峰”的目前公认的异常乳果糖呼气氢试验定义的有效性。
对28名受试者进行近端小肠抽吸物培养以及10克乳果糖呼气氢试验并结合闪烁扫描。测定胃十二指肠pH值、胃细菌过度生长的有无以及过度生长菌群体外发酵乳果糖的能力。
单独的乳果糖呼气氢试验对小肠细菌过度生长的敏感性（16.7%）和特异性（70.0%）较差。与闪烁扫描相结合可使特异性达到100%，因为盲肠细菌发酵乳果糖可能导致连续呼气氢浓度出现双峰。闪烁扫描使敏感性提高到38.9%，因为在这种疾病中，在试验餐到达盲肠之前呼气氢浓度可能会出现单次升高。无论所使用的小肠细菌过度生长的定义、过度生长菌群的性质、有利的管腔pH值、同时存在的胃细菌过度生长情况，还是过度生长菌群体外发酵乳果糖的能力如何，敏感性仍然不理想。
基于呼气氢浓度出现双峰的异常乳果糖呼气氢试验定义是不合适的。即使加上闪烁扫描，该试验也不能成为一种临床上有用的替代抽吸物培养来诊断小肠细菌过度生长的方法。
