Helicobacter pylori culture as a key tool for diagnosis in Colombia.

INTRODUCTION: The presence of H. pylori in the stomach is associated with gastric pathologies. However, its diagnosis through culture methods is challenging because of its complex nutritional requirements and microaerophilic conditions for optimal growth. The preferred method for rapid diagnosis of H. pylori is the Rapid Urease Test (RUT) from human biopsies, which relies on the high activity of the urease enzyme present in H. pylori. However, RUT cannot say much more information about H. pylori. This makes evident the need for bacterial culture to know essential information such as the strain type, the kind of infection present and the bacteria's antibiotic susceptibility. METHODOLOGY: Gastric biopsies from 347 patients were used for H. pylori isolation. We correlated the culture results with the RUT and histological grading used at Hospital Universitario Fundación SantaFe de Bogotá (HU-FSFB), Colombia. The concordance between techniques was determined by the Cohen's Kappa coefficient (K). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were also calculated. RESULTS: The culture standardization was successful, and it could be applied for diagnosis in the clinical practice. H. pylori was positive by culture in 88 (26.34%) patients. The concordance of RUT and culture was strong (K= 0.805), and between histology and culture was moderate (K= 0.763) as well as for the gold standard defined and culture (K= 0.80). CONCLUSIONS: We present evidence that RUT and histological methods will be better interpreted for diagnosis of H. pylori if combined with bacterial isolation in cholesterol enriched culture.

Evaluation of Helicobacter pylori Infection and Clarithromycin Resistance in Strains From Symptomatic Colombian Children.

The aim of the study was to determine the current prevalence of Helicobacter pylori in symptomatic Colombian children and evaluate the presence of mutations associated with clarithromycin resistance. Biopsies from 133 children were analyzed. The gastric fragment was used for urease test and reused for polymerase chain reaction sequencing of the 23SrDNA gene. Mutations were detected by bioinformatic analysis. Polymerase chain reaction sequencing established that H pylori infection was present in 47% of patients. Bioinformatics analysis of the 62 positive sequences for 23SrDNA revealed that 92% exhibited a genotype susceptible to clarithromycin, whereas the remaining strains (8%) showed mutations associated with clarithromycin resistance. The low rate of resistance to clarithromycin (8%) suggests that conventional treatment methods are an appropriate choice for children. Recycling a biopsy that is normally discarded reduces the risks associated with the procedure. The 23SrDNA gene amplification could be used for a dual purpose: detection of H pylori and determination of susceptibility to clarithromycin.