Helicobacter pylori seroepidemiology in risk groups

Helicobacter pylori gastritis in HIV-infected patients: a review

BACKGROUND

The risk factors for acquiring Helicobacter pylori and Human Immunodeficiency Virus (HIV) infections are different: H. pylori is transmitted by gastro- or fecal-oral routes and is associated with low socioeconomic conditions, while HIV is transmitted through sexual intercourse, infected body fluids, and transplacentally. If the host responses to these infections were independent, the prevalence of H. pylori should be similar in HIV-infected and non-infected patients. Yet, several studies have detected a lower prevalence of H. pylori in patients with HIV infection, whereas other studies found either no differences or greater rates of H. pylori infection in HIV-positive subjects.

OBJECTIVE

To review studies that addressed the issue of these two simultaneous infections and attempt to determine whether reliable conclusions can be drawn from this corpus of often contrasting evidence.

METHODS

Electronic literature search for relevant publications, followed by manual search of additional citations from extracted articles.

RESULTS

The initial search yielded 44 publications; after excluding case reports, reviews, narrowly focused articles, and duplicate reports, there remained 29 articles, which are the corpus of this review. With one exception, all studies reported higher rates of H. pylori infection in HIV-negative subjects. Five studies also examined the CD4 lymphocyte counts and found an inverse correlation between the degree of immunosuppression and the prevalence of active H. pylori infection.

CONCLUSIONS

Current evidence suggests that it is likely that H. pylori needs a functional immune system to successfully and persistently colonize the human gastric mucosa.

Does HIV infection alter the incidence or pathology of Helicobacter pylori infection?

Gastrointestinal (GI) discomfort is a common complaint among patients infected with HIV. GI symptoms can be caused by a myriad of factors including but not limited to coinfections, antiretroviral therapy, medications for opportunistic infections, and nutritional status. Some researchers have hypothesized that Helicobacter pylori infection may be more common among HIV-infected patients as a result of immune suppression. An increased incidence of H. pylori infection would contribute to the prevalence of GI complaints in this population. Several epidemiologic studies have examined the relationship between H. pylori infection and HIV. While studies have generally reported conflicting results that may be related to the use of varied study designs, some identifiable patterns can be discerned. It does appear that the incidence of H. pylori infection is lower among patients with AIDS compared to matched HIV-infected and -uninfected controls. This review discusses the various epidemiologic trials that have been conducted in this area and describes the potential physiologic mechanisms to explain these findings. The clinical applicability of these studies as well as limitations are also discussed. A greater number of well-designed and controlled trials are needed before any definitive conclusions regarding these diseases can be made, until such time clinicians should be aware of the potential issues regarding H. pylori screening and management in the context of HIV. Research in this area might also provide information relating to HIV-associated GI changes and the role of these changes in HIV pathogenesis.

High seroprevalence of Helicobacter pylori infection in non-institutionalised children with mental retardation

Eighty-four children with mental retardation (34 boys, 50 girls; age range 2-18 years, median 6 years) and 84 age- and gender-matched outpatient controls were studied. All children were living at home, had never stayed in an institution, and came from the same urban area. Seropositivity for Helicobacter pylori was found in 42 (50%) of 84 mentally retarded children and 16 (19%) of 84 controls (p < 0.01). Socio-economic factors did not differ between the two groups. The findings indicated that a higher prevalence of H. pylori infection occurs in children with mental retardation, regardless of whether they are institutionalised.

The prevalence and related symptomatology of Helicobacter pylori in children with recurrent abdominal pain

The aim of the study was to assess and compare the IgG seroprevalence of H. pylori in children with recurrent abdominal pain with healthy children and to investigate the related symptoms. IgG antibodies against low-molecular weight H. pylori antigens were assessed in 438 children with recurrent abdominal pain and in 91 healthy controls. Sera with an ELISA unit-value above the cut-off level were confirmed by Western immunoblot. Only seropositive children with recurrent abdominal pain were examined by an oesophago-gastro-duodenoscopy. Symptomatology was recorded according to the localization of the abdominal pain, presence of pyrosis, nocturnal pain, relation of pain to meals and bowel irregularities. The seroprevalence was 21% (95% CI: 17-25%) in the children with recurrent abdominal pain and 10% (95% CI: 5-18%) in the healthy controls (p = 0.30). In seropositive children with RAP H. pylori was found in 46/66 by culture and histology. The presence of H. pylori was significantly associated with active or inactive chronic gastritis. The presence of H. pylori was associated with both parents being born in a country with a high prevalence and a low social class. Helicobacter pylori-positive children had more often pain related to meals than the H. pylori-negative children. No differences among the two groups were seen according to the levels of haemoglobin, leucocytes, thrombocytes, weight and height. In conclusion, the seroprevalence of H. pylori is comparable in children with recurrent abdominal pain and healthy children. No specific symptomatology was seen in H. pylori-positive children with RAP.

Modification of Christensen urease test as an inexpensive tool for detection of Helicobacter pylori

About half the world population is infected with Helicobacter pylori. Most live in developing countries where clinical studies face the constraints of high costs of imported rapid diagnostic tests. In this work, we describe and validate a simple local urease test (LUT) to determine the presence of the bacterium in gastric biopsies, and report the incidence of infection among symptomatic patients in Caracas, Venezuela. Statistical comparison of LUT and CLOtest (Delta West, Bentley, Australia) (N = 216 patients) showed that the probability of 95% agreement between the two test was 0.936. Overall incidence of infection determined by the LUT was 65% (N = 229), and it was higher in patients from public (72%; N = 153) than from private (50%; N = 76) hospitals (p = .001). Therefore, the incidence of infection differs in two socioeconomic groups that coexist in the same city. LUT may represent an affordable tool in clinical studies needed to identify social factors that increase the risk of infection by H. pylori.