Primary culture of Helicobacter pylori from gastric biopsies obtained by endoscopy

Objetive: To determine the feasibility of Helicobacter pylori bacteria culture in Costa Rica through documentation of sample collection, comparison of histopathological diagnosis, and description of diagnoses associated with isolates obtained with rapid urease results.

Methods: Descriptive investigation involving patients between the ages of 35 and 70 years, of both sexes, who attended the Digestive Endoscopy Service of the Hospital Clínica Bíblica between February and June 2019 for a gastroscopic study. Gastric biopsies were obtained for histopathological diagnosis, rapid urease test, and Helicobacter pylori culture. For the latter, biopsies were transported in a semisolid transport medium, the tissue was macerated and cultured on Skirrow agar and Helicobacter selective agar; one plate of each medium was incubated at 37 °C in microaerophilia for 48 hours to 10 days. Culture positivity was determined by observation of colonial morphology and the bacteria were identified by the microscopic new analysis, Gram staining, and biochemical tests (catalase, urease, and oxidase).

Results: Forty-four patients were included (age: 50.6 ± 10.0, 54.5% male). Helicobacter pylori were recovered in biopsies from 27 patients (61.4% success rate). Bacterial recovery was similar in Skirrow and Helicobacter selective media. The weekly recovery success rate increased during the study to reach 100% success at week 11. The culture was compared with rapid urease in 27 patients and the agreement between the two methods was Cohen’s kappa coefficient of 0.48. Culture detected the bacteria in 56% of patients, rapid urease in 37%, and the combination of both techniques allowed detection in 60%. The most frequent endoscopic diagnosis in patients with positive culture was erythematous gastritis and superficial chronic gastritis and the predominant histopathological diagnosis was chronic gastritis with gastric atrophy. The diagnosis by culture coincided with the detection of toluidine blue in 80.4% of the cases.

Conclusions: Helicobacter pylori culture can be implemented in Costa Rica. This study had a bacterial recovery rate of 61.4%. Combining the culture method with the rapid urease test and histological detection contributes to an accurate and timely diagnosis. Based on the protocols described in this research, we recommend that each laboratory standardize the conditions that allow a good recovery percentage and an implementation adapted to their routine activities.