Helicobacter pylori virulence genes detected by string PCR in children from an urban community in northeastern Brazil. J Clin Microbiol. 2013;51:988-989. [PMID: 23254125 DOI: 10.1128/jcm.02583-12]

Surveillance of Helicobacter pylori resistance over 22 Years (2000-2021) in Northern Spain

OBJECTIVES

Helicobacter pylori gastritis is considered an infectious disease, regardless of symptoms and stage of disease. Most consensus documents recommend empirical therapy based on local antimicrobial susceptibility patterns. We aimed to provide clinically useful information about primary and secondary antimicrobial resistance to antimicrobials commonly prescribed for H. pylori.

METHODS

Overall, 31,406 gastroduodenal biopsies and 2,641 string tests from patients over 15 years of age were plated on selective media, isolating H. pylori in 36.7% of biopsies and 50.7% of string tests. Susceptibility testing could be performed in 96.6% (12,399/12,835) of H. pylori isolates. Polymerase chain reaction (PCR) was also used to detect H. pylori and its resistance to clarithromycin, providing susceptibility data for 112 patients with negative culture results.

RESULTS

Resistance to amoxicillin and tetracycline was unusual (0.6% and 0.2%, respectively). Rates of primary resistance to clarithromycin and metronidazole remained steady over the 22-year study period, at around 14% for clarithromycin and 30% for metronidazole, while primary resistance to levofloxacin tripled (from 7.6% in 2000 to 21.7% in 2021, P < 0.001) and increased with patient age. Notably, 1.8% of isolates were multiresistant to clarithromycin, metronidazole, and levofloxacin. Overall, secondary resistance rates were higher (P < 0.0001) than primary resistance rates for clarithromycin (42.5% vs 14.1%), metronidazole (40.9% vs 32%), and levofloxacin (21.5% vs 17.1%).

CONCLUSION

Determination of susceptibility for H. pylori by culture and/or PCR in patients undergoing endoscopy could facilitate the implementation of tailored therapy and guide the choice of empirical therapy when susceptibility testing cannot be performed, potentially helping limit the emergence of antimicrobial resistance.

Clarithromycin-resistant H. pylori primary strains and virulence genotypes in the Northeastern region of Brazil

The increase of H. pylori resistance to clarithromycin is a concern. This study evaluated the prevalence of H. pylori’s primary resistance to clarithromycin and its association with virulence factors in adult dyspeptic patients and asymptomatic children. The gastric mucosa from patients (153 gastritis, 24 gastric cancer, 21 peptic ulcer) and gastric juice obtained by string test from 24 H. pylori and 23S rRNA positive asymptomatic children were included. The clarithromycin resistance was assessed by TaqMan RT-PCR 23S rRNA point mutations, A2142G and/or A2143G, and H. pylori virulence markers by PCR. Overall, the clarithromycin resistance was 14.4% (32/222), 14.2% in adults, and 12% in children, whereas origin, gender, and disease were not distinctive factors. The most prevalent point mutation was A2143G (62.5%). The point mutation was significantly less frequent in cagA-positive (11.4%) than in cagA-negative (23.6%) strains (p=0.03 OR = 0.4 95%CI = 0.19 - 0.91) as well as in cagE-positive (10.2%), cagE-negative (21.2%) (p=0.03 OR: 0.4 I.C:0.20-0.91). No difference was found in iceA or vacA alleles genotypes. Primary resistance to clarithromycin was lower than that reported in Southeast Brazil. The cagA and cagE positive H. pylori samples have few point mutations suggesting that individuals infected with virulent strains may be more susceptible to anti-H. pylori treatment.

Helicobacter pylori virulence genes

Helicobacter pylori (H. pylori) is one of the most important human pathogens, infecting approximately half of the global population. Despite its high prevalence, only a subset of H. pylori infected individuals develop serious gastroduodenal pathology. The pathogenesis of H. pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host, environmental and bacterial virulence factors. H. pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment, movement towards the gastric epithelium, and attachment to gastric epithelial cells. These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H. pylori infection, causing chronic inflammation and tissue damage, which may eventually lead to the development of peptic ulcers and gastric cancer. Numerous studies have focused on the prevalence and role of putative H. pylori virulence genes in disease pathogenesis. While several virulence factors with various functions have been identified, disease associations appear to be less evident, especially among different study populations. This review presents key findings on the most important H. pylori virulence genes, including several bacterial adhesins and toxins, in children and adults, and focuses on their prevalence, clinical significance and potential relationships.

oipA "on" status of Helicobacter pylori is associated with gastric cancer in North-Eastern Brazil

Background

Although, outer membrane protein OipA of Helicobacter pylori has been associated with gastric mucosal damage and gastroduodenal diseases, studies evaluating gastric cancer patients are scarce. We investigated whether the functional oipA “on” status was associated with gastric cancer in the North-eastern Brazil, region with high prevalence of gastric cancer.

Methods

We included samples from 95 H. pylori positive subjects (23 patients with gastritis, 24 with gastric cancer, 32 first-degree relatives of gastric cancer patients and 16 children). oipA was assayed by polymerase chain reaction (PCR) and DNA sequencing. cagA and vacA status were evaluated by PCR.

Results

Overall 81.1% of the H. pylori strains had functional oipA. In adults, the oipA “on” status (OR = 9.20; 95%CI = 1.45–58.48, P = 0.02) and increasing age (OR = 1.08; 95%CI = 1.03–1.14; P = 0.003) were independently associated with gastric cancer in a logistic model. The oipA “on” status (OR = 14.75; 95%CI: 2.53–86.13, P = 0.003) was also associated with first-degree relatives of gastric cancer patients when compared with gastritis. The frequency of oipA “on” status did not differ between children and adults (P = 0.87). The oipA “on” status was significantly correlated with the presence of cagA and vacA s1 m1.

Conclusion

oipA “on” status was independently associated with gastric cancer and first-degree relatives of gastric cancer patients in North-eastern Brazil.

[Prevalence of Helicobacter pylori cagA, vacA, and iceA genotypes in children with gastroduodenal diseases]

OBJECTIVE

To investigate the prevalence of cagA, vacA, and iceA genotypes in the isolated strains of Helicobacter pylori (H.pylori) from children with gastroduodenal diseases in Jiangxi, China, as well as the association between cagA, vacA, and iceA genotypes and the type of gastroduodenal diseases.

METHODS

The samples of gastric antral mucosa were collected from 316 children with gastroduodenal diseases in Jiangxi, and a total of 107 strains of H.pylori were isolated. The genomic DNA of these strains was extracted, and PCR was used to determine the ureA, cagA, vacA, and iceA genotypes.

RESULTS

Of all the 107 isolated strains of H.pylori, the detection rates of ureA and cagA genes were 100% (107/107) and 94.4% (101/107) respectively. The overall detection rate of vacA gene was 100% (107/107), and the detection rates of vacAs1a, vacAs1c, vacAm1, and vacAm2 genes were 74.8% (80/107), 25.2% (27/107), 29.9% (32/107), and 69.2% (74/107) respectively, with both vacAm1 and vacAm2 genes detected in 0.9% (1/107) of all H.pylori strains. In the chimera of vacA gene, the detection rates of vacAs1a/m1, vacAs1a/m2, vacAs1c/m1, and vacAs1c/m2 genes were 26.2% (28/107), 51.4% (55/107), 3.7% (4/107), and 17.8% (19/107) respectively (P<0.001). The detection rates of iceA1 and iceA2 genes were 79.4% (85/107) and 9.3% (10/107), respectively (P<0.001), and both iceA1 and iceA2 genes were detected in 7.5% (8/107) of all strains. The detection rates of the genotypes of H.pylori showed no significant differences between the peptic ulcer, chronic gastritis, and duodenal bulbar inflammation groups (P>0.05).

CONCLUSIONS

The dominant genotypes of H.pylori are cagA, vacAs1a/m2, and iceA1, and there are mixed infections with H.pylori strains of different genotypes in children with gastroduodenal disease from Jiangxi, China. The genotypes of H.pylori are not associated with the type of gastroduodenal disease.

[Prevalence of Helicobacter pylori cagA, vacA, and iceA genotypes in children with gastroduodenal diseases]

OBJECTIVE

To investigate the prevalence of cagA, vacA, and iceA genotypes in the isolated strains of Helicobacter pylori (H.pylori) from children with gastroduodenal diseases in Jiangxi, China, as well as the association between cagA, vacA, and iceA genotypes and the type of gastroduodenal diseases.

METHODS

The samples of gastric antral mucosa were collected from 316 children with gastroduodenal diseases in Jiangxi, and a total of 107 strains of H.pylori were isolated. The genomic DNA of these strains was extracted, and PCR was used to determine the ureA, cagA, vacA, and iceA genotypes.

RESULTS

Of all the 107 isolated strains of H.pylori, the detection rates of ureA and cagA genes were 100% (107/107) and 94.4% (101/107) respectively. The overall detection rate of vacA gene was 100% (107/107), and the detection rates of vacAs1a, vacAs1c, vacAm1, and vacAm2 genes were 74.8% (80/107), 25.2% (27/107), 29.9% (32/107), and 69.2% (74/107) respectively, with both vacAm1 and vacAm2 genes detected in 0.9% (1/107) of all H.pylori strains. In the chimera of vacA gene, the detection rates of vacAs1a/m1, vacAs1a/m2, vacAs1c/m1, and vacAs1c/m2 genes were 26.2% (28/107), 51.4% (55/107), 3.7% (4/107), and 17.8% (19/107) respectively (P<0.001). The detection rates of iceA1 and iceA2 genes were 79.4% (85/107) and 9.3% (10/107), respectively (P<0.001), and both iceA1 and iceA2 genes were detected in 7.5% (8/107) of all strains. The detection rates of the genotypes of H.pylori showed no significant differences between the peptic ulcer, chronic gastritis, and duodenal bulbar inflammation groups (P>0.05).

CONCLUSIONS

The dominant genotypes of H.pylori are cagA, vacAs1a/m2, and iceA1, and there are mixed infections with H.pylori strains of different genotypes in children with gastroduodenal disease from Jiangxi, China. The genotypes of H.pylori are not associated with the type of gastroduodenal disease.

Frequency of virulence genes in mixed infections with Helicobacter pylori strains from a Mexican population

BACKGROUND

Helicobacter pylori (H. pylori) is associated with gastroduodenal diseases. Virulence of clinical isolates is related to clinical outcome. Moreover, with microdiversity studies in clinical isolates from a single patient, but from a different origin (antrum or corpus), it is possible to demonstrate that there are simultaneous mixed infections.

AIMS

To genotype H. pylori strains with multiplex PCR, according to their clinical virulence, and in this manner know the frequency of each genotype and relate it to clinical outcome in order to prevent the development of severe diseases.

METHODS

A total of 210 patients with gastric alterations were studied. Virulence classification of H. pylori strains was carried out with multiplex PCR and 127 strains were identified as H. pylori by PCR (glmM and cagE). Genotype and clinical outcome were evaluated with the Fisher's exact test. In addition, RAPD-PCR was performed as a fingerprinting method to analyze mixed infections.

RESULTS

The cagA, vacAs1, and vacAm1 genes were detected in all the clinical isolates. Strains were classified as: type i, 40.15% (51/127); type ii, 22.04% (28/127); and type iii, 28.4% (36/127), but two new different genotypes were also detected: (1) babA2+, cagA+, vacAs1+, 6.29% (8/127) and (2) babA2+, cagA-, vacAs2/m2+, 3.14% (4/127). The cagE gene was detected in type i strains.

CONCLUSIONS

The Fisher's exact test did not support a significant association between clinical outcome and genotype. The main circulating genotypes in the Mexican population studied were: cagA+, vacAs1, and vacAm1. Multiplex PCR can be used as a screening test for H. pylori strains. Furthermore, the cagE gene is a good marker for identifying cag-PAI positive strains.

Antral gastritis caused by Helicobacter pylori infection in the pediatric age group is associated with increased mesenteric lymph node dimension observed by ultrasonography

BACKGROUND

To find out if transabdominal ultrasonography (US) may have a predictive role for detection of antral gastritis and Helicobacter pylori (HP) infection in the antrum of pediatric age group.

METHODS

A total of 91 (63.6%) patients and 52 (36.4%) controls were allocated into two groups as follows: Group 1 (n=91): patients with complaints and endoscopic findings consistent with gastritis and documented HP infection; Group 2 (n=52): patients with complaints and endoscopic findings consistent with gastritis in the absence of documented HP infection. These two groups were compared in terms of demographics and biggest mesenteric lymph node detected, muscularis mucosa thickness, submucosal thickness, muscularis propria thickness, and total gastric wall thickness.

RESULTS

The two groups exhibited no statistically significant difference with respect to age (P=0.747), and presenting symptoms (P=0.982). However, the mesenteric lymph node dimension was significantly increased in Group 1 (P=0.039). Median mesenteric lymph node dimension was 12.9 (±15.4) mm in Group 1, while 11.0 (±12.8) mm in Group 2. No significant difference was observed between groups in terms of muscularis mucosa thickness (P=0.243), submucosal thickness (P=0.174), muscularis propria thickness (P=0.356), and total gastric wall thickness (P=0.223).

CONCLUSIONS

Antral gastritis caused by HP infection in the pediatric age group is associated with increased mesenteric lymph node dimension observed by US.

Persistent and transient Helicobacter pylori infections in early childhood

BACKGROUND

Helicobacter pylori, the main cause of peptic ulcer disease and gastric cancer in adult populations, is generally acquired during the first years of life. Infection can be persistent or transient and bacterial and host factors determining persistence are largely unknown and may prove relevant for future disease.

METHODS

Two cohorts of healthy Chilean infants (313 total) were evaluated every 3 months for 18-57 months to determine pathogen- and host-factors associated with persistent and transient infection.

RESULTS

One-third had at least one positive stool ELISA by age 3, with 20% overall persistence. Persistent infections were acquired at an earlier age, associated with more household members, decreased duration of breastfeeding, and nonsecretor status compared to transient infections. The cagA positive strains were more common in persistent stools, and nearly 60% of fully characterized persistent stool samples amplified cagA/vacAs1m1. Persistent children were more likely to elicit a serologic immune response, and both infection groups had differential gene expression profiles, including genes associated with cancer suppression when compared to healthy controls.

CONCLUSIONS

These results indicate that persistent H. pylori infections acquired early in life are associated with specific host and/or strain profiles possibly associated with future disease occurrence.

CagA phosphorylation EPIYA-C motifs and the vacA i genotype in Helicobacter pylori strains of asymptomatic children from a high-risk gastric cancer area in northeastern Brazil

Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric diseases. Virulence factors such as VacA and CagA have been shown to increase the risk of these diseases. Studies have suggested a causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown to be geographically diverse. We investigated the number of CagA EPIYA motifs and the vacA i genotypes in H. pylori strains from asymptomatic children. We included samples from 40 infected children (18 females and 22 males), extracted DNA directly from the gastric mucus/juice (obtained using the string procedure) and analysed the DNA using polymerase chain reaction and DNA sequencing. The vacA i1 genotype was present in 30 (75%) samples, the i2 allele was present in nine (22.5%) samples and both alleles were present in one (2.5%) sample. The cagA-positive samples showed distinct patterns in the 3&#8217; variable region of cagA and 18 of the 30 (60%) strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C motifs. We confirmed that the studied population was colonised early by the most virulent H. pylori strains, as demonstrated by the high frequency of the vacA i1 allele and the high number of EPIYA-C motifs. Therefore, asymptomatic children from an urban community in Fortaleza in northeastern Brazil are frequently colonised with the most virulent H. pylori strains.

Detection of genotypic clarithromycin-resistant Helicobacter pylori by string tests

AIM

To evaluate the utility of the string test to detect genotypic clarithromycin-resistant Helicobacter pylori (H. pylori) by polymerase chain reaction (PCR)-restriction fragment length polymorphism.

METHODS

Patients undergoing endoscopic examinations were enrolled in the present study. String tests were done on the next day of endoscopy. Segments of 23S rRNA were amplified from DNA obtained from string tests. PCR-restriction fragment length polymorphism was accomplished by restriction enzymes BbsI and BsaI recognizing the mutation site A to G at 2143 or at 2142 of 23S rRNA domain V, respectively.

RESULTS

One hundred and thirty-four patients with H. pylori infection underwent string tests. To compare phenotypic resistance, 43 isolates were successfully cultured in 79 patients in whom 23S rRNA was successfully amplified. Of five patients with clarithromycin-resistant H. pylori, 23S rRNA of H. pylori isolates from four patients could be digested by BsaI. In 38 susceptible isolates, 23S rRNA of H. pylori isolates from 36 patients could not be digested by either BsaI or BbsI. The sensitivity and specificity of the string test to detect genotypic clarithromycin resistance were 66.7% and 97.3%, respectively. Positive and negative predictive values were 80% and 94.7%, respectively.

CONCLUSION

String test with molecular analysis is a less invasive method to detect genotypic resistance before treatment. Further large-scale investigations are necessary to confirm our results.

Association among H. pylori virulence markers dupA, cagA and vacA in Brazilian patients

Background

Only a few Helicobacter pylori-infected individuals develop severe gastric diseases and virulence factors of H. pylori appear to be involved in such clinical outcomes. Duodenal ulcer promoting gene A (dupA) is a novel virulence factor of Helicobacter pylori that is associated with duodenal ulcer development and reduced risk for gastric carcinoma in some populations. The aims of the present study were to determine the presence of dupA gene and evaluate the association among dupA and other virulence factors including cagA and vacA in Brazilian patients. Gastric biopsies were obtained from 205 dyspeptic patients (100 children and 105 adults). DNA was extracted and analyzed for the presence of H. pylori and its virulence factors using the polymerase chain reaction method.

Results

Patients with gastritis tested positive for H. pylori more frequently. The dupA gene was detected in 41.5% of them (85/205); cagA gene was found in 98 isolates (47.8%) and vacA genotype s1/m1 in 50.2%, s1/m2 in 8.3%, s2/m2 in 36.6%, s2/m1 in 0.5% and s1/s2/m1/m2 in 4.4%. We also verified a significant association between cagA and dupA genes [p = 0.0003, relative risk (RR) 1.73 and confidence interval [CI] = 1.3–2.3]. The genotypes s1/m1 were also associated with dupA gene (p = 0.0001, RR: 1.72 and CI: 1.3–2.2). The same associations were found when analyzing pediatric and adult groups of patients individually.

Conclusion

Ours results suggest that dupA is highly frequent in Brazilian patients and is associated with cagA gene and vacA s1/m1 genotype, and it may be considered an important virulence factor in the development of gastric diseases in adults or children.

Helicobacter pylori in pediatrics

This review concerned the important pediatric studies published between April 2012 and March 2013. Symptomatology in Helicobacter pylori-positive children is nonspecific, except for those suffering from peptic ulcer diseases. Investigation of H. pylori status in children and adolescents with sideropenic anemia is recommended, and it is the aim of several studies worldwide. Associations of H. pylori with plasma ghrelin levels as well as the negative association of H. pylori with atopic disease were interesting objectives for several studies this year. Success rates of sequential therapy tended to be lower in recent studies than in previous trials, which probably reflects the increase in macrolide resistance. A beneficial effect of probiotics was reported although not all trials supported this result in children. Intrafamilial transmission and young age could be major risk factors associated with reinfection in children.