H pylori Flashcards
1
Q
what is H. pylori
A
-Gram-negative, curved
or spiral bacterium
-Flagellated – highly motile
-Ideally adapted to survive in the human stomach (Potent producer of urease, which breaks down urea in gastric juice – has a little cloud that protects it, Protected from highly acidic environment)
-H. pylori is a small, curved, highly motile, Gram-negative bacillus that colonizes the mucus layer of the human stomach where it is ideally adapted to survive. It is a potent producer of urease, which breaks down urea in the gastric juice to produce carbon dioxide and two ammonium ions. The ammonium protects it from the highly acidic gastric environment
2
Q
epidemiology of H. pylori infection
A
- Person-to-person passage of H. pylori, gastric-oral and fecal-oral, are likely modes of transmission. H. pylori infection is usually acquired in childhood and becomes chronic if not cleared or treated. It is likely that in developed countries H. pylori is picked up from siblings, other children, or parents, predominantly by the gastro-oral route. In developing countries, fecal-oral transmission is important in acquiring infection.
- H. pylori colonizes the human stomach, and various risk factors are associated with H. pylori infection: infection of family members; increased number of siblings (>2); crowded living conditions and clustering (eg, institutions, day-care centers, and health care facilities); poor sanitation (fecal contamination of water and food), and poor hygiene. Although day-care attendance appears to be moderately associated with H. pylori infection, the effect appears to be more substantial in areas with a high prevalence of infection.
- The prevalence of H. pylori infection has been consistently found to be higher in adults than in children, likely reflecting a birth cohort effect caused by a higher incidence in the past due to poor living conditions and sanitation.
- Most common mode of transmission is mother to child
- If you don’t have H pylori now, you wont get it – adult to adult transmission is very rare, adult to child is common
3
Q
worldwide geography of H. pylori infection
A
- Although H. pylori is estimated to inhabit more than half of the world’s population, prevalence rates vary widely between geographical regions and ethnic groups. While the map shown depicts a rough estimation of H. pylori prevalence, it should be noted that these data are derived from multiple studies in various populations/ethnicities across varying time periods and with significant methodologic differences (eg, method of diagnosis, number of patients).
- Overall, rates of H. pylori infection are markedly higher among developing countries than developed countries. Prevalence rates approaching or exceeding 90% have been observed among various populations in Bangladesh, Egypt, Russia, Siberia, and Africa. In contrast, the prevalence of H. pylori infection among developed countries is substantially lower, with recent estimates ranging from 6.8% to 79% in the United States, 7.3% to 70% in Europe, and 15.5% to 23% in Australia. The dramatic differences in prevalence of H. pylori infection appears to be inversely proportional to socioeconomic status.
4
Q
H pylori in adults and children in the US
A
- The highest rates of acquisition are before age 10 years3,4 and generally becomes a chronic infection without treatment5
- Why talk about H. pylori today?
- The actual prevalence of H. pylori among adults and children in the US may be higher than physicians realize.1,2
- H. pylori is a common chronic infection that affects adults and children1,2
- In the United States, approximately 25% of children had evidence of H. pylori infection (data from NHANES III survey of children aged 6 to 19 years) and approximately 30% of adults had evidence of H. pylori infection1,2
- Research shows that the highest rates of acquisition of the infection are before the age of 10 years3,4
- Without treatment, H. pylori may become a chronic infection that can last decades or be a lifelong infection5
- Rates of H. pylori are notably higher in minority groups, as high as 65% in Mexican Americans, 52% in nonblack Hispanics compared with 21% in non-Hispanic whites6
- A VA center study with 1200 patients aged 40-80 years showed higher prevalence among black males for any age group followed by Hispanic males and non Hispanic whites, respectively7
- Highest prevalence is seen among black males aged 50-59 years7
5
Q
race/ethnic disparities in H pylori
A
- Substantial disparities in the prevalence of H. pylori seropositivity exist among different racial/ethnic groups in the United States. In this analysis involving data from the National Health and Nutrition Examination Survey (NHANES) 1999‒2000, H. pylori status was determined using a commercially available enzyme-linked immunosorbent assay (ELISA). Among the 4145 participants aged 20 years or older with known H. pylori status, the age-standardized proportion of seropositivity was 30.7% (95% CI: 27.9‒33.6).
- As shown, there is a higher prevalence of seropositivity among non-Hispanic blacks and Mexican Americans compared with that of non-Hispanic whites. Moreover, multivariate logistical analysis indicated that non-Hispanic black and Mexican American races/ethnicities have a significantly higher odds of H. pylori infection even after adjustment for age, socioeconomic factors, and country of origin. Further, the seropositivity by age curves shown suggests a high incidence of seropositivity in youth and early adulthood among these populations, followed by a significant decline in incidence with age. The factors driving sustained prevalence of seropositivity among non-Hispanic blacks and Mexican Americans remain uncertain and require further understanding of how H. pylori infection is transmitted and about lifetime rates of seroconversion and seroreversion in these groups.
6
Q
H. pylori infection
A
- Acute H. pylori infection causes transient hypochlorhydria and is rarely diagnosed. Chronic gastritis will develop in virtually all persistently infected individuals, but 80-90% will not exhibit symptoms. The further clinical course is highly variable and depends on bacterial and host factors. Patients with higher acid output are likely to have antral-predominant gastritis, which predisposes them to duodenal ulcers (DU). Patients with lower acid output are more likely to have gastritis in the body of the stomach, which predisposes them to gastric ulcer (GU) and can initiate a sequence of events that, in rare cases, leads to gastric carcinoma. H. pylori infection induces the formation of mucosa-associated lymphoid tissue (MALT) in the gastric mucosa. Malignant lymphoma arising from such MALT tissue is a rare complication of H. pylori infection
- Can cause cancer in the stomach!!! This is why we care about ulcers
7
Q
long term consequences of H pylori
A
- If left untreated, infection with H. pylori can lead to serious long-term consequences.
- Most infected individuals experience asymptomatic gastritis, although peptic ulceration may occur in 10%–15% of the infected population1
- The incidence of gastric cancer is lower, with approximately 1% of infected individuals developing adenocarcinoma of the stomach (though in some countries the lifetime risk of gastric cancer is 11–12%2) and even fewer experiencing gastric mucosa-associated lymphoid tissue (MALT) lymphoma1
- H. pylori is recognized as the major trigger for a sequence of phenotypic changes in the gastric mucosa that may progress from inflammation to superficial gastritis, then onto chronic atrophic gastritis, intestinal metaplasia, dysplasia, and finally, carcinoma. In fact, the WHO and International Agency for Research on Cancer regard H. pylori as a Group 1 carcinogen3
- The link between H. pylori infection and nonulcer dyspepsia remains controversial4
8
Q
who do you test for H pylori
A
- All pts with positive test should be treated, so key issue is who to test?
- Patients with active or historical PUD
- Gastric mucosa-associated lymphoid tissue (MALT) lymphoma
- History of gastric cancer
- Uninvestigated dyspepsia <60 years and w/o alarm features
- ? Iron deficiency, pre-bariatric surgery, ITP, family hx gastric CA, prior to long-term NSAID Rx
- Patients with nonulcer dyspepsia
- Patients with gastroesophageal reflux disease
- Persons using NSAIDs
- Patients with unexplained iron deficiency anemia
- Populations at higher risk for gastric cancer
9
Q
Gastric cancer in the US
A
- An estimated 21,600 new cases of gastric cancer annually
- > 10,000 deaths per year
- Cancer incidence patterns among first-generation immigrants nearly identical to those of their native country
- Gastric cancer continues to pose considerable burden in the United States, and an estimated 21,600 new cases will be diagnosed in 2013 and almost 11,000 men and women will die of the disease in 2013.
- As shown (right), based on patients diagnosed in the United States from 2006‒2010, the age-adjusted incidence rates were highest among blacks (16.1 and 8.7 per 100,000 for males and females, respectively), followed by Asian/Pacific Islanders (15.5 and 9.3 per 100,000), Hispanics (14.9 and 8.6 per 100,000), American Indian/Alaska Natives (13.1 and 7.7 per 100,000), and whites (9.2 and 4.5 per 100,000).
10
Q
can H. pylori treatment reduce the risk for gastric cancer
A
-The effectiveness of H. pylori eradication in reducing risk for gastric cancer was also assessed in this meta-analysis of randomized controlled trials
-The pooled analysis of 6 studies that included a total of 6695 patients with
4–10 years of follow-up showed that eradication treatment reduced gastric cancer risk
-Notably, the majority of these trials were conducted in Asia
11
Q
test and treat strategy
A
- The American Gastroenterological Association (AGA) Medical Position Statement on Evaluation of Dyspepsia is outlined in this slide. The recommendation to test and treat is based on randomized controlled trials and the possible impact of eradication in preventing future gastric adenocarcinoma.
- Both the American College of Gastroenterology (ACG) and the American Gastroenterological Association (AGA) recognize alarm features, or “red flags,” that help identify patients who need early/prompt investigation with endoscopy in order to rule out peptic ulcer diseases, esophagogastric malignancy, and other rare GI tract diseases.
- Dyspeptic patients more than 55 years old, or those with alarm features, should undergo prompt endoscopy to rule out peptic ulcer disease, esophagogastric malignancy, and other rare upper gastrointestinal tract disease.
- In patients aged 55 years or younger with no alarm features, test and treat for H. pylori using a validated, non-invasive test and a trial of acid suppression if eradication is successful. H. pylori testing is optimally performed by a 13C-urea breath test or stool antigen test, which are discussed later. If symptoms do not resolve, an empiric trial of acid suppression with a PPI for 4 weeks is recommended. In patients who are H. pylori negative, a PPI trial of 4-6 weeks is recommended. The patient may need reassurance or a reassessment of diagnosis if there is no response, and an EGD may then be considered.
12
Q
helicobacter and functional dyspepsia
A
- Review of all well-designed studies indicates a statistically significant benefit in the successful eradication of HP in uninvestigated dyspepsia
- Unfortunately the magnitude of the benefit is small: 5-10% reduction in dyspepsia vs placebo
- The critical and unresolved issue is whether the marginal benefit of eradication of HP for dyspepsia is sufficient to justify antibiotic therapy in all patients
13
Q
ACG guidelines: preventing NSAID-related ulcers
A
-“H. pylori infection increases the risk of NSAID-related gastrointestinal (GI) complications”
-“There is potential advantage of testing for
H. pylori infection and eradicating the infection
if positive in patients requiring long-term NSAID therapy”
-“All patients regardless of risk status who are about to start long-term traditional NSAID therapy should be considered for testing for H. pylori and treated, if positive”
-This slide outlines the recent ACG practice guidelines on the prevention of NSAID-related ulcer complications. The guidelines discuss the results of a meta-analysis that concluded that H. pylori infection increases the risk of NSAID-related gastrointestinal complications. Thus, the ACG recommends that there is potential advantage to testing for H. pylori infection and eradicating the infection in H. pylori-positive-patients requiring long-term NSAID therapy
14
Q
are there possible benefits of H. pylori infection
A
- Despite the well-recognized associations of H. pylori infection with peptic ulcer disease, gastritis, and gastric carcinoma, a growing number of studies suggest that H. pylori infection may be protective of certain conditions
- GERD, obesity, diarrhea, Barrett’s esophagus, IBD, Asthma, Allergy, Dermatitis, Esophageal eosinophilia
15
Q
Options for H. pylori testing
A
- Endoscopic: Easy, accurate and inexpensive, IF endosopy appropriate (nut bot an appropriate sole indication for EGD)
- Non-Endoscopic (Passive: serology, Active: Urea breath test (UBT), Stool antigen test)
- Methods available for detecting current infection of H. pylori are divided into two groups: invasive (endoscopic) or non-invasive (non-endoscopic). Testing for H. pylori is routinely undertaken non-endoscopically using serology, UBT, or stool antigen detection. Testing can also be undertaken at endoscopy via biopsies, histology, or culture.
