High Prevalence of Clarithromycin Resistance and cagA , vacA , iceA2 , and babA2 Genotypes of Helicobacter pylori in Brazilian Children

Abstract

We isolated 45 Helicobacter pylori strains from 217 child patients. Resistance to clarithromycin, metronidazole, amoxicillin, and tetracycline was detected in 27%, 13%, 4%, and 0% of strains, respectively. The A2143G mutation was the most prevalent (67%) among clarithromycin-resistant strains. In addition, strain genotyping revealed a significant association between gastritis severity and the simultaneous presence of cagA, vacA s1m1, iceA2, and babA2 genes.Helicobacter pylori infection is found worldwide and constitutes a public health concern in many countries. Previous epidemiological studies have shown a high prevalence of H. pylori infection in Brazil (2,20,24). H. pylori infection, generally acquired in childhood, persists asymptomatically for decades in most individuals.Amoxicillin, tetracycline, metronidazole, and clarithromycin are frequently used, combined with proton pump inhibitors or bismuth salts, for the treatment of H. pylori infections (25). However, antibiotic resistance is frequently associated with eradication failure (3, 16). Resistance to metronidazole and clarithromycin is population dependent, and several studies suggest that clarithromycin resistance is higher in strains isolated from children than in strains isolated from adults (10). In Brazil, the prevalence of clarithromycin-resistant strains in adults is reported to be from 7 to 10% (15, 18). However, little is known about the prevalence of clarithromycin-resistant H. pylori infection in Brazilian children.The primary aims of this study were to determine the prevalence of clarithromycin-resistant H. pylori strains in children, to identify those isolates via rapid methodology, and to examine the severity of gastritis caused by the antibiotic-resistant H. pylori isolates. Metronidazole, amoxicillin, and tetracycline resistance was also studied. Furthermore, the study aimed to genotype the vacA and iceA genes and to detect the cagA gene in gastric biopsy specimens, since recent studies found a high frequency of cagA-positive and iceA2-positive strains as well as a strain with the vacA signal region genotype s1 and middle region sequence m1 among pediatric H. pylori isolates in Brazil (6,7,11,23). This is also the first investigation of babA2 gene prevalence in Brazilian children.A total of 217 consecutive child patients, aged 1 to 18 years (mean age, 10 years) (105 girls and 112 boys), who underwent Gastric biopsy specimens were processed for histological examination and evaluated according to the updated Sydney system of classification and grading of gastritis (4).Antral gastric specimens were transported in sodium thioglycolate broth (Difco, Detroit, MI) in an ice bath and ground before submission to DNA extraction and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis with primers specific to the H. pylori 23S rRNA gene (17). The QIAmp tissue kit (Qiagen) was used for DNA extraction. Point mutations related to clarithromycin resistance in the 23S rRNA amplicon were investigated in all H. pylori isolates by PCR-RFLP usin...

Frequency of Helicobacter pylori blood-group antigen-binding adhesion 2 and sialic acid binding adhesion genes among dyspeptic patients in Tabriz, Iran

“…The association of babA2 gene with different clinical outcomes has been shown in several studies. [13][14][15] Our findings are not in agreement with the study conducted by Arevalo-Galvis et al, who reported 57.0% of isolates were babA2 positive and more often found in patients with duodenal ulcer. Furthermore, other South American studies report that this gene frequency range from 46.0 to 82.3%.…”

“…14 Garcia et al, showed babA2 gene frequency in the Brazilian population is high, and is in association with various upper gastrointestinal diseases. 15 In Costa Rica, the prevalence of babA2 was 73.7%, which was higher than in Western studies (38.0-43.0%), but lower than that of Asian studies, also in Japanese patients (96.8%). 5 In Mexico, similar to our study, babA2 frequency is low (21.7%).…”

“…Thus, our present clinical and experimental data do not confirm previous experimental studies that represent a key role of babA2 in the pathogenesis of ulcer disease. 14,15 It is important to note that there is substantial allelic variation in babA2 gene and additional adherence gens. The association of babA2 gene with different clinical outcomes has been shown in several studies.…”

cagE as a biomarker of the pathogenicity of Helicobacter pylori

“…Similar percentages were found by studies conducted in Colombia and in Brazil. In the latter, only the iceA gene was discordant 38,39 . In patients with enanthematous gastritis, the combination of babA2/vacAs2m2/ iceA2 was detected in 22.6% (7/31).…”

Non-invasive detection of Helicobacter pylori virulence genotypes ureA, vacA, cagA and babA2 among asymptomatic Egyptian infants

“…The current data is consistent with the results reported in Poland (Maciorkowska et al, 2007) and Shanghai (Zhou et al, 2010) where the s1m2 was the most prevalent genotype. In contrast, other predominant vacA genotypes were reported in Brazil, Slovenia, the Mid-western United States (s1m1), and Spain (s2m2) (Podzorski et al, 2003;Homan et al, 2009;Agudo et al, 2010;Garcia et al, 2010).…”