Epidemiological and Clinical-Pathological Aspects of Helicobacter pylori Infection in Brazilian Children and Adults

Aim To evaluate the prevalence and risk factors of H. pylori infection in the pediatric and adult population seen at a public hospital in São José do Rio Preto, SP, Brazil. Methods This is a retrospective study that evaluated 2406 medical records of children, adolescents, and adults with dyspeptic symptoms who underwent upper gastrointestinal endoscopy. H. pylori diagnosis and demographic and clinical-pathological features were recorded. Results A total of 852 subjects were H. pylori positive, with an overall prevalence of infection of 35.4%, occurring mainly in adults over 40 years of age, and a 24.7% prevalence considering only children and adolescents. No association was observed between H. pylori infection and risk factors. However, the H. pylori positive individuals showed a higher frequency of pangastritis (p < 0.01), severe lesions (p = <0.001), and erosive lesions (p = 0.04). The bacterium was eradicated in 83.5% (127) of the patients who received the standard therapy. Conclusions The prevalence of H. pylori detected in a public service in São José do Rio Preto, SP, Brazil, is as expected for developed countries, showing growing rates with increasing age. As H. pylori infection occurs during childhood, screening programs for detection and prevention in the pediatric population are important to reduce the prevalence of this infection in adults.


Introduction
The infection by Helicobacter pylori (H. pylori), a gramnegative bacterium, is among the most frequent infections worldwide, affecting about 50% of the global population and an estimated 4.4 billion individuals likely to be infected in 2015 worldwide [1].
H. pylori infection causes chronic inflammation and is the main etiologic agent associated with chronic gastritis, peptic and duodenal ulcer, MALT (mucosa-associated lymphoid tissue) lymphoma, and gastric adenocarcinoma [2]. Having been recognized as a risk factor for stomach cancer, H. pylori was classified by the International Agency for Research on Cancer [3] as a class I carcinogen, which was involved in 90% of all gastric malignancies [4]. The clinical consequences of H. pylori infection are determined by multiple factors, including genetic predisposition of the host, especially certain cytokine polymorphisms, environmental factors, such as high dietary salt intake, smoking, and drinking, besides heterogeneity of H. pylori strains [5].
The bacterial virulence factors such as cagA (cytotoxinassociated gene A) and its pathogenicity island (cag PAI) and vacA (vacuolating cytotoxin A) are associated with more severe inflammation of the gastric mucosa, conferring a greater risk of developing gastric carcinoma and a poorer clinical outcome of the infection [6,7]. In general, it is observed that colonization by the bacteria causes a severe systemic immune response, inducing the production of proinflammatory cytokines, reactive oxygen species (ROS), and reactive nitrogen species (RNS), activation of NF-κB (transcription factor nuclear factor), cellular proliferation, and survival factors [6,7]. All these changes can alter cellular homeostasis and trigger the malignant progression cascade to gastric cancer, such as chronic gastritis, atrophic gastritis, intestinal metaplasia, dysplasia, and gastric adenocarcinoma [8].
The gastric cancer incidence and mortality rates remain globally high, especially in Asia and Eastern Europe and also in developing countries of South America [5]. It is the fifth most common cancer type worldwide and the third leading cause of cancer-related death, occurring mainly in China, Japan, and Korea [1,9]. In Brazil, it ranks fourth in incidence and second in death rate [10].
H. pylori is often acquired in childhood due to fecaloral and oral-oral transmission and is associated with socioeconomic conditions, particularly sanitary conditions, socio-demographic subgroups, high household density, low education levels, and rural residence [1,11].
Although most infected individuals are asymptomatic, if not treated, H. pylori infection may persist for decades in its hosts and promote the development of gastrointestinal diseases [12]. Thus, H. pylori eradication is considered a first-line treatment to achieve the eventual regression of acute and chronic inflammation and to prevent malignant progression [5]. Considering that a reduction in the prevalence of H. pylori can contribute significantly to a decline in the incidence of gastric cancer, a better understanding of its epidemiology may help developing prevention and intervention programs for this infection, which in turn will result in a decrease of the incidence of this neoplasm.
Brazil is a very large country, with great regional differences as to the quality of life and health. Some epidemiologic studies have reported great variation in the prevalence of H. pylori according to the region investigated, showing a higher prevalence in the north of the country compared to the south [13][14][15][16]. The aim of this study was to determine the prevalence of H. pylori infection and risk factors in pediatric and adult patients seen at a public hospital in São José do Rio Preto, SP, Brazil. Hospital-based studies are important to predict population estimates and establish programs for the prevention and control, information for population, and treatment of H. pylori infection. Demographic and clinical-pathological features such as age, gender, place of residence (rural or urban), H. pylori diagnosis, endoscopy diagnosis according to the Sydney system [17], therapy for H. pylori infection eradication, alcohol consumption (nondrinkers or social consumption x everyday drinkers), and smoking (current smoker or former smoker x non-smoker) were collected from the medical records. The standard triple therapy for bacterium eradication consisted of amoxicillin (1 g), clarithromycin (500 mg), and omeprazole (20 mg), all twice daily for seven days. All this information was stored in an Excel database, using codes without identifying the individuals.

Materials and Methods
2.1. Statistical Analysis. Descriptive analysis was used for calculating the mean age and other parameters evaluated. Fisher's exact test was also used to determine the association between H. pylori infection and the parameters gender, age, residence, alcohol consumption, smoking habits, treatment, and eradication. Mean values were compared using the T test. Statistical analysis with a significance level of p < 0 05 was performed using GraphPad Prism software v.6.01. Table 1 shows the distribution of demographic and clinicalpathological characteristics of subjects with dyspepsia who underwent UGE. In the 2406 medical records evaluated, the prevalence of H. pylori infection considering all age groups was 35.4% (852). The mean age of H. pylori positive (Hp+) and H. pylori negative (Hp−) individuals was similar (47 ± 15 years versus 48 ± 17 years). However, when the subjects were stratified by age group, there was a higher prevalence of H. pylori infection in adults between 40 and 60 years (p < 0 001).
Of the 852 Hp+ individuals, the medical records contained information about the bacterial eradication therapy for 245, of which 80% (196) claimed to have correctly carried out the proposed treatment. Of the 196 subjects who followed the treatment, 83.5% (127) had the bacterium eradicated, as confirmed by a negative result in a second endoscopy examination.
Considering the individuals who underwent UGE, only 1.8% (15) of the Hp+ group versus 2.5% (39) of the Hp− group had a normal stomach according to the endoscopy diagnosis, while most had some type of gastric lesion (Hp+ = 98.2% versus Hp− = 97.5%). In both groups, the most common lesions diagnosed according to the Sydney system were gastritis and pangastritis, besides other less frequent gastric lesions such as polyps and peptic ulcers; intestinal metaplasia was observed in one subject of the Hp+ group.
In another analysis, we analyzed only children and adolescents aged less than or 18 years, corresponding to 3.2% (77/2406) of all assessed medical records (Table 3). In this group, only 19 individuals were Hp+, with a prevalence of 24.7% of bacterial infection. The mean age in the Hp+ group (16.2 ± 1.9 years, range 10-18years) was similar to that of the uninfected group (15.2 ± 2.3 years, range 9-18 years, p = 0 12). Regarding gender, the prevalence of females was higher among both infected (89.5%) and uninfected subjects (75.9%). Most of them (94.7% of Hp+ and 89.1% of Hp−) were of urban origin. In the Hp+ pediatric   group, endoscopy showed 100% of individuals with endoscopic lesions, while in the Hp− group 97.5% (51) it showed some type of gastric lesion, and 2.5% (7) of them had a normal mucosa. As to the endoscopic classification of gastritis (Table 4), the Hp+ pediatric individuals showed mainly pangastritis (66.7%) followed by antral gastritis (33.3%), while the Hp− individuals had mostly antral gastritis (58.8%) followed by pangastritis (41.2%). Regarding the intensity of the lesions, while the Hp+ pediatric individuals showed mainly moderate lesions, the Hp− subjects had mostly mild lesions; however, the differences between the groups were not significant. Regarding the category, both groups showed mainly enanthematous gastritis.

Discussion
Our study evaluated clinical-epidemiological features of H. pylori infection in both the adult and pediatric population of the Brazilian Southeast region, in a city of the São Paulo State inland. The overall infection prevalence was 35.4%, occurring mainly in adults over the age of 40 years. We did not detect any significant differences between the infected and the noninfected groups regarding gender, place of residence, tobacco smoking, alcohol intake, and endoscopic diagnosis. However, the H. pylori positive individuals showed a higher frequency of pangastritis, lesions of severe intensity, and erosive lesions.
H. pylori prevalence estimates show a great variation globally, with rates varying from 15.1% in developed countries (Australia) to 87.7% in developing countries (Nigeria) [1,18]. In addition, there are great regional variations within the same country [1,19]. For 2015, it was estimated that approximately 4.4 billion individuals were infected by H pylori worldwide [1]. However, in the last decades, due to improvements in sanitation, health, sociocultural conditions, and eradication methods, a decline of the H. pylori infection prevalence has been observed in different countries, concomitant with a decrease of the peptic ulcer disease and gastric cancer [1,18]. These findings reinforce the idea that bacterial eradication in areas of high gastric cancer prevalence reduces the risk of this neoplasm [2]. Our results are within the range reported for developed countries of North America (37.1%) and Europe (34.3%) [1].
In Brazil, epidemiological studies to estimate the H. pylori prevalence among children and adults have shown different rates according to the regions and time periods assessed. In the Northeast and Midwestern regions, higher prevalence rates are reported (63%-96%) [13,14]. In contrast, in the Southeastern region, lower rates are reported, as for São Paulo (SP) 76.3% and Rio de Janeiro (RJ) 59.5% [13]. However, in the cities of the São Paulo State inland, elevated frequencies, over 85%, have been detected [13]. In contrast, recently Frugis et al. [20] observed a significantly decreased H. pylori prevalence in a private healthcare service of São Paulo, going from 19.3% in 2004 to 14.1% in 2014, concomitantly with improvements in health and socio-cultural conditions. In line with these findings, our results show a low prevalence rate of H. pylori infection in the region of São José do Rio Preto, as compared to other cities in Brazil and other countries ( Table 5).
São José do Rio Preto is located in the Northwestern part of the State of São Paulo and is the State's 12 th biggest city. Its HDI (Human Development Index) was 0.797 in 2010, as measured by the IBGE (Brazilian Institute of Geography and Statistics), an index similar to Rio de Janeiro (0.799) and São Paulo (0.805) [21]. This index shows very good living conditions and health quality, with demographic and social indicators similar to developed cities.
Considering the relevance of H. pylori infection in childhood, we also evaluated children and adolescents. In this group the prevalence of the bacterium was lower, i.e., 24.7%. Another study, conducted in a public hospital in São Paulo, detected a seroprevalence of 35.6% in children, which increased with age, reaching 58.3% in those aged over 12 years [15] However, in children aged 4-11 years from Salvador (BA), the seroprevalence of H. pylori was found to be 28.7% [22], similar to our study. In the Salvador city study, the authors also observed that H. pylori infection was associated with increasing age and variables indicative of poor hygiene and crowded living conditions. Queiróz et al. [23] compared the prevalence of H. pylori infection in children of Belo Horizonte (Brazil), Santiago (Chile), and London (UK) and observed a higher prevalence in Latin America (35%) than in the UK (7%). In contrast, a review made in the city of Porto (Portugal) showed high prevalence of infection in children between 4-5 years (26%) and in adolescents (66%), with rates increasing to 73.9% between 18-30 years and exceeding 88% in individuals over 40 years of age [24]. These findings are consistent with recent estimates showing that Portugal has higher rates of H. pylori infection (86.4%) [1]. On the other hand, although Africa also shows a high prevalence rate (79.1%) [1], recently Awuku et al. [25] observed a low prevalence (14.2%) of H. pylori infection among children in a rural environment in Africa, associated with increasing household numbers, female gender, source of drinking water other than pipe  and borehole, open-air defecation, and younger age. These findings corroborate that the prevalence of H. pylori infection is highly variable in different regions and related to socioeconomic status and hygiene and sanitary conditions. Thus, improvements in these factors should contribute to the prevention of H. pylori infection in childhood and consequently in adults.
Regarding clinical and pathological factors associated to H. pylori prevalence, we did not detect significant differences in gender, smoking and drinking habits, or other features such as place of residence and endoscopic diagnosis between the Hp positive and Hp negative groups. However, we observed that the prevalence of H. pylori increases with age, as reported by other studies [15,22,24,26]. Regarding gender, some studies show that the infection by H. pylori is virtually the same in both genders [19,27,28], as found in the present study, but it can be positively associated with alcohol consumption [19,28].
When we evaluated the endoscopy classification of gastritis considering all age groups, in both infected and noninfected individuals, the H. pylori positive patients showed mainly pangastritis of moderate or severe intensity and of the erosive category, whereas in the H. pylori negative individuals enanthematous antral gastritis of moderate or mild intensity was more frequent. All the H. pylori positive children and adolescents showed endoscopic lesions, more frequently pangastritis of moderate intensity. In a community of northern Canada, Cheung et al. [28] also detected a high prevalence of gastric lesions among H. pylori positive individuals, mainly chronic gastritis (100%), acute gastritis (94%), gastric atrophy (21%), and intestinal metaplasia (11%) with inflammation of moderate (47%) and severe (47%) intensity. In a pediatric population, Queiróz et al. [23] reported an association between H. pylori infection with gastric endoscopy findings such as the presence of antral and corpus erythema and antral nodularity, as well as with the degree of antral and corpus active and chronic inflammation in the H. pylori positive children.
Another important aspect of our study was the finding of an 83.5% eradication rate after H. pylori therapy, confirmed by a second endoscopy after treatment. This value is below the recommended efficiency rate, supposed to achieve ≥90% eradication [29]. However, the cure rate after standard triple therapy plus bismuth as a first-line treatment for H. pylori infection has shown great variation globally: 55-94% [29]. In Latin America, after initial treatment, a mean eradication rate of 72.2% (ranging from 30.2% to 100%) has been observed. In Brazil, the eradication success rate ranges from 60.4% to 100% [30]. It should, however, be pointed out that the eradication rate has decreased over time to below 80%, due mainly to multiple antibiotic resistance and patient compliance [12,31,32]. According to Gisbert and MacNicholl [29], scoring over 85% eradication rate may require two or more optimization strategies. The standard therapy employed in the patients treated in the present study consisted of the classical triple regimen composed of clarithromycin, amoxicillin, and a protonpump inhibitor for seven days. However, quadruple therapy in combination with bismuth compounds or sequential/ concomitant therapy has been recommended by European guidelines for a longer period of time (14 days) for highresistance individuals [29,33]. Prolongation of treatment to 14 days improved the eradication success rates in patients with resistant strains, increasing the cure rates. Moreover, the concomitant therapy has been found to be more effective than the standard triple and sequential therapy for H. pylori eradication [29]. This data reinforces the importance of H. pylori treatment and eradication, leading to reversion of acute and chronic inflammation and possibly to reversion of preneoplastic lesions and prevention of malignant progression [12,31].
A limiting factor of our study is that it was performed in a sample of patients with dyspeptic symptoms who underwent upper gastrointestinal endoscopy, thus a hospital-based study, which may not reflect the pattern in the general population. Therefore, it is an important further community-based study with a large number of individuals to obtain more accurate data on the prevalence of H. pylori in the general population.
In conclusion, our data show that the prevalence of H. pylori detected in a public healthcare service in São José do Rio Preto (SP) is similar to that expected for developed countries, showing growing rates with increasing age. Moreover, considering that the infection occurs in childhood, screening programs for detection and prevention in the pediatric population are important to reduce the prevalence of H. pylori infection in adults. Thus, further studies are needed, to cover a larger geographic extension in Brazil, since the bacterial infection is widely distributed. They should also allow a better understanding of its epidemiology by analyzing the various environmental and socioeconomic conditions likely to influence its prevalence in each population group.

Data Availability
The manuscript did not use the data generated by the public databases. All data of the patients were collected from the medical records of Hospital João Paulo II. All this information was stored in an Excel database, using codes without identifying the individuals, and they are stored under the custody of the responsible researcher (AES).

Conflicts of Interest
All authors declare no conflicts of interest.

Authors' ContributionS
AES, ACTC, GWM, and RA conceived the study. EPT, FFM, MPD, and LOMG collected the data from the medical records. MAP and VSB analyzed the data. AES and MAP wrote the manuscript. All authors read and approved the final manuscript.