pylori infection. In children, especially in the youngest, the usefulness of the diagnostic test based on the detection of H. pylori-specific IgG antibodies (serum, urine, whole blood, saliva) is controversial due to their low sensitivity. Okuda et al. [35] evaluated the accuracy of two urinary IgG antibodies tests (Urine-HpELISA test and Rapid urine-HpAb) obtaining sensitivity and specificity of 91.9% and 96.9% for Urine-HpELISA and 78.4% and 100% for Rapid urine-HpAb and recommended these methods as simple, low cost, rapid, and reliable for screening of H. pylori. Histopathologic find more studies are still important to identify mucosal lesions. Carvalho et al. analyzed histopathologic lesions in 96 Brazilian

children with H. pylori infection. 70.5% had moderate-to-severe chronic active gastritis. Intestinal metaplasia was not found, Trichostatin A molecular weight and gastric atrophy was not significant. 61.9% had pangastritis, and H. pylori density was higher in the antrum than in the corpus [36]. Molecular methods have been used for different purposes: detection of H. pylori in gastric biopsies compared with conventional methods, detection of virulence genes, both in biopsy specimens and in specimens other than biopsies obtained using less invasive methods (string test) or noninvasive methods (stool samples). Ou et al. [37] found that the fluorescent quantitative PCR test was more sensitive than conventional methods alone or in combination (p<0.01). A nested

PCR had a sensitivity of 93.0% and a specificity of 100% compared with the 13C-urea breath test (UBT) on gastric DNA obtained by a string test in asymptomatic children [2]. Baskovich et al. [38] also detected a surprisingly high number of new cases with H. pylori by PCR, in both the normal biopsies and test cases, suggesting that PCR could detect colonization in asymptomatic patients. The sensitivity and specificity of the glmM gene compared with UBT was 42.6% and 100%, respectively, in stools of patients with dyspepsia [1]. Multilocus sequence typing MLST of total DNA extracted from fecal specimens to genotype H. pylori was successfully Janus kinase (JAK) used by Osaki et al. [21]. Antibiotic resistance is

the major cause of failure in the treatment of H. pylori infection. Most of the studies worldwide confirmed an increase in macrolide resistance, while metronidazole resistance either decreased or remained stable. In a prospective multicentre European study, primarily comprised of adults, Megraud et al. [39] found a 31.8% resistance rate to clarithromycin and 25.7% to metronidazole in the 311 H. pylori isolates from children from eight countries included in the study. The increase in clarithromycin resistance in many countries (especially in Western/Central and Southern Europe) has prohibited its empirical use in standard therapeutic regimens. Hojsak et al. [40] found a 17.9% resistance to azithromycin, 11.9% to clarithromycin, 10.1% to metronidazole, and 0.