High Prevalence and Recent Increase in Multidrug-Resistant Helicobacter pylori in Bulgarian Patients: Pros and Cons of Culture-Based Susceptibility Testing

We investigated the anti-Helicobacter pylori activity of five antibiotics against isolates from 226 symptomatic adult patients during two periods (2024–2026 and 2022–2023). Antibiotic susceptibility testing (AST) was performed by MIC test strips and/or a validated disk diffusion method for tetracycline. Overall resistance was 58.8% for metronidazole, 57.1% for clarithromycin, 41.2% for levofloxacin, 9.3% for amoxicillin, and 3.5% for tetracycline. Resistance rates to 1, 2, and 3–5 antibiotics (the latter defined as multidrug resistance, MDR) were 28.8%, 33.6%, and 23.9%, respectively. In 2024–2026, metronidazole and clarithromycin resistance prevalence exceeded 62%, and four patients/isolates had quadruple/quintuple resistance. In the second period, MDR rates were twice as high as in the first period, reaching 27.1% and 29.9%, respectively. Culture-based AST can detect resistance due to various mechanisms in H. pylori and determine exact (low or high) resistance levels. Briefly, we found high resistance rates to metronidazole, clarithromycin, levofloxacin, and MDR during the last few years, possibly due to high national antibiotic consumption. Phenotypic AST is useful for choosing individualized/tailored eradication regimens in treated patients in countries/regions with high H. pylori resistance/MDR. In the era of growing antibiotic resistance, culture-based AST is important and, therefore, should not be neglected.