Maternal and infant Helicobacter pylori infections:
Correlation between Infected Mothers and Their Infants
Flor Puentes & Jason Astorga
Supervised and directed by
Thomas Redlinger, PhD
Bridges to the Future
University of Texas at El Paso
23 August 1999
Helicobacter pylori is a curved rod organism that lives in the human stomach, it is a gram negative spiral flagellate and the primary cause of gastric ulcers. Curved rod organisms were first reported in animal stomachs in 1893 .
Warren and Marshall were the first to report that they had seen a curved bacillus in the human stomach. They named the curved bacteria Camplyobacter pylori. In 1989 the decision was taken by international agreement that this organism in fact represented a whole new genus and it was called Helicobacter pylori.
Where does Helicobacter pylori live and what does it do? H. pylori live in the human gastric mucosa and have not been found to thrive elsewhere. H. pylori in peptic ulceration are the primary cause of ulcer disease. This infection in most cases is asymptomatic. But less than 20% of individuals harboring the infection will acquire gastric diseases such as gastritis, ulcer diseases, gastric-associated lymphoma, and potentially gastric cancer . Acquisition during childhood is common in the developing world. In the U.S. approximately 25% of children are infected with H. pylori. The overall H. pylori prevalence in the U.S. is 33% . The objective of the research study was to determine the prevalence of Helicobacter pylori in mothers and their children in Socorro, TX. Studies are being conducted around the world to understand the manner in which H. Pylori is transmitted.
II. Materials and Methods
A. Sample collection at clinic
The study was conducted at a Women Infant and Children (WIC) clinic in Socorro, TX. WIC mothers bring their babies to the clinic at 6 month for a scheduled exam. This exam consists of questionnaires, breath test, weigh and measurement of baby and a blood sample by heel stick. The breath test consists of obtaining two samples of breath. The first is a baseline sample breath test. The second is taken twenty minutes later after the baby is given 50 mg of urea mixed with a half ounce of juice. The blood sample is processed by centrifugation at 5,000 rpm for 3 minutes and removed to a clean tube.
B. Lab Analysis
Samples are transported to the laboratory at UTEP. The breathe samples are placed in the IRIS 13C (Infra Red Isotope Analyzer). This machine measures the 13CO2 and 12CO2 concentration from a breath sample and relates their ratio to the 13C stable isotope standard . Figure 1 shows how 13CO2 are produced from labeled urea. Helicobacter pylori IgG antibodies were determined in the samples using the EIA (Enzyme Immunoassay). The assay consists of pipeting 5ul of serum into a precoated microtiter plate containing the H. pylori antigen. It is incubated for 20 min., at 20° C. The microtiter wells are washed 3 times with wash buffer. The antibody/ antigen reaction is determined using a conjugated second antibody containing the enzyme peroxides.
A total of 100ul of conjugate is added to each well and incubated for 20 min. at 20° C. Adding 100ul of 1N H2SO4 to each well terminates the reaction and a plate reader measures color intensity at 450nm. Calculations of results for EIA are determined using cutoff values based on standard calibrator values of standards. Absorbency readings are converted into ELISA values using a best-fit linear regression program. ELISA values >2.2 were considered H. pylori positive and <1.8 negative. Those values between 2.2 and 1.8 are indeterminate and for purpose of this study are considered negative.
We tested 100 mothers for H. pylori antibodies and found that 47% were H. pylori positive and 53%were negative. We also tested their children at age 6 months and out of 103 children, 15.5% tested positive and 84.5% negative for H. pylori antibodies. Therefore, the prevalence of H. pylori antibodies in mothers and their children was 47% and 15.5% respectively. Figure 2 shows the percentages of the four combinations of positive/negative mothers and their babies.
Of the positive mothers, 35 (42.7%) had negative babies and 11(73.3%) had positive babies (Table 2). Of the H. pylori positive babies, 4 (26.7%) had negative mothers and 11 (73.3%) had positive mothers (Figure 3). This indicates that if the baby was H. pylori positive that the mother was most likely H. pylori positive. An odd ratio calculation indicates that mothers infected with Helicobacter pylori antibodies are 3.7 times more likely to have children who in the first six months of life will be infected with Helicobacter pylori (Table 3). Finally, a chi square test (Table 2) showed a significant relationship between H. pylori positive mothers and their infants (P=0.03).
This research has shown that mothers who live in Socorro, TX are 3.7 times more likely to have babies that are H. pylori positive. Since the mother is usually the person more closely associated with or in intimate contact with the baby, this suggests that
H. pylori may be transmitted from mother to baby after birth.
We also found that babies, who are H. pylori positive, 73.3% of the time had mothers who were positive. This indicates that if the baby is positive chances are that the mother is also positive. Again, the mother is usually the one in closest contact with the baby for the first six months and therefore is the most probable source of the baby's H. pylori is infection.
1. Heatley, R., The Helicobacter pylori Handbook. Second ed. 1998, Oxford: Blackwell Science. 64.
2. Marshall, B. and J. Warren, Unidentified curved bacilli in the stomach of patients with gastritis and peptic ulceration. Lancet, 1984. 1: p. 1311-1315.
3. Graham, D., H pylori-Associated Gastrointestinal Diseases. Vol. 1. 1998, Newton, Penn.: Health Care Co. 142.
4. Staat, M.A., et al., A population-based serologic survey of Helicobacter pylori infection in children and adolescents in the United States. Journal of Infectious Diseases, 1996. 174(5): p. 1120-3.
5. Wagner, G., IRIS Technical Data Sheet. 1999: p. 4.
Table 1. Positive and negative H. pylori infected percentage of mothers and infants.
H. pylori negative
Figure 1. Diagram showing how urea is broken down into ammonia and CO2 in the stomach .
Figure 2. Pie graph showing four possible mom and baby H.pylori combination
Figure 3. Bar graph showing H.pylori positive babies born to either negative or positive mothers.
Table 2. Cross tab table showing the percentage of mothers and babies that are H.pylori positive and negative.
(AD) / (BC) = ODDS RATIO
(47 x 11) / (35 x 4) = 3.7
Table 3. Relative Risk Calculation?