The Department of Pathology and Laboratory Medicine

HELICOBACTER PYLORI: The role of serology in the diagnosis and management of ulcer disease Author: Paul Hurtubise, Ph.D., Professor

Interest in the role of Helicobacter pylori in gastric pathology dates back to 1983 when Warren and Marshall reported successful in vitro cultivation of this organism from gastric epithelium of patients with chronic active gastritis.(1) Since then this organism, formerly called Campylobacter pyloridis, has been implicated to be a cause of duodenal and gastric ulceration(2), and a major cofactor in the development of gastric carcinoma and possibly gastric lymphoma.(3) H. pylori is a gram negative, spiral shaped organism that colonizes the mucosa of the stomach creating constant microscopic inflammation which can be clinically silent in patients for a long time. When the infection is eliminated, the inflammation subsides. The organism is reported to be present in 95% of patients with duodenal ulcers, and 60-90% of those with gastric ulcers. Studies have demonstrated that elimination of the organism significantly reduces the risk of recurrence of peptic ulcers. Individuals with gastrointestinal symptoms and with evidence of H. pylori colonization are considered to be infected, whereas individuals without gastrointestinal symptoms but with evidence of the presence of the organism are said to be colonized. Diagnostic methods to detect the presence of H. pylori are divided into two groups, direct and indirect which are summarized in the table below.

Guides to Using H. pylori Serological Testing Serologic testing should be performed only on patients with gastrointestinal symptoms and should not be used as a screen for H. pylori colonization or infection due to the high frequency of positive serologic tests in asymptomatic individuals. Serologic detection of IgG antibodies to H. pylori has been shown to be an accurate indicator of both current and past H. pylori colonization. The prevalence of H. pylori antibody is equal in both sexes and increases with age peaking between the ages of 30-60+ years. Blacks, Hispanics and persons born outside the United States show higher rates of colonization and presence of antibody. Virtually all infected individuals possess this antibody, however, the intensity of antibody response is not correlated with the presence of severity of symptoms. Interpretation The serological test for H. pylori is available from the Diagnostic Immunology Laboratory (Test #8416). Results are reported as seronegative, equivocal, or seropositive. Equivocal results indicate that it may be too early in the infection for the patient to have developed a strong antibody response. Follow-up testing in three weeks is recommended in these cases. Because of the high prevalence of H. pylori antibodies there are limitations to the interpretation of positive serologic results. While a positive result indicates the patient has developed antibodies to H. pylori, it does not prove that existing symptoms are due to infection or colonization, nor can it differentiate between active and past infection. A clinical diagnosis of gastritis or ulcers related to the presence of H. pylori antibodies depends, in addition to a positive serology, upon the patient's clinical signs, symptoms and history. The assay also has limitations if it is used to monitor the results of antibiotic therapy since it may take months before there is a decrease in the titer of H. pylori antibody. References Warren JR, Marshall BJ, Unidentified Curved Bacilli on Gastric Epithelium in Active Chronic Gastritis. Lancet 1983;1:1273-1275. Nomura A, Stemmermann GN, Chyou P-H, Perez-Perez G, Blaser MJ. Helicobacter pylori Infection and the Risk for Duodenal and Gastric Ulceration. Ann Int Med 1994;120:977-981. Normura A, Stemmermann GN, Chyou P-H, Kato I, Perez-Perez GI, Blaser MJ. Helicobacter pylori Infection and Gastric Carcinoma among Japanese Americans in Hawaii. N Engl J Med 1991;325:1132-6. Brown KE, Peura DA. Diagnosis of Helicobacter pylori Infection. Gastroenterology Clinics of North America. 1993;22(1):105-115.