Helicobacter Pylori: Old And New Challenges In The Microbiological Diagnosis

Background and AimHelicobacter pylori (HP) is an oncogenic agent, involved in preventable upper digestive malignant or premalignant conditions. The use of antibiotic therapy to eradicate HP infection, as indicated by guidelines, may be ineffective if resistance to them is unknown. The aim of this work was to cultivate HP from gastric biopsies and to perform antibiotic susceptibility testing.Materials and MethodsBetween June and December 2018, a sample of patients with suggestive gastric symptoms consulted at the 2nd Medical Clinic in Cluj-Napoca, Romania, who exhibited positive HP fecal antigen and agreed to undergo gastric endoscopy and prelevation of biopsy specimens for bacterial culture, have been included in this study. Biopsy specimens collected for bacterial culture were transported to the laboratory for cultivation. Special growth conditions have been ensured: microaerobic atmosphere, selective media, and longer growth time compared to other bacteria (1014 days). For all isolated strains antibiotic susceptibility testing was performed using E-tests for clarithromycin, levofloxacin, metronidazole, amoxicillin and disc diffusion method for tetracycline and rifamycin.ResultsTwenty-six adult patients (7 men, 19 women) underwent gastric endoscopies and gastric biopsies during the recruitment period. After sample processing and culture, only 8 strains of HP were obtained, despite the fact that all investigated patients presented positive HP fecal antigen.One strain was resistant to 3 antibiotics, two strains were resistant to 2 antibiotics, 4 strains to one antibiotic. Six of the eight isolated HP strains were resistant to metronidazole (75%), three were resistant to levofloxacin (37.5%), one was resistant to amoxicillin (12.5%) and one was resistant to clarithromycin (12.5%).ConclusionsIsolation of HP after gastric biopsy allows for antibiotic susceptibility testing, however, successful cultivation of HP raises a number of difficulties. Given the small number of HP strains isolated so far in this study, the above figures regarding antibiotic resistance are a very rough and preliminary approximation that will be refined as our study continues.