RESUMEN
Background: Helicobacter pylori is a pathogenic bacterium that infects a significant number of individuals. At present, therapeutic strategies to eradicate this bacterium depend on our knowledge of its resistance to antimicrobials. Aims: To evaluate the primary resistance of H pylori to metronidazole (Mtz), clarithromycin (Cla), and tetracycline (Tet) in symptomatic out-patients. Material and Methods: Fifty independent isolates of H pylori were obtained by endoscopy-assisted gastric biopsy from patients attending the University of Chile Clinical Hospital, that previously had not been treated with an eradication regime against this bacterium. The minimal inhibitory concentration of each antimicrobial was determined by agar dilution method. Results: Forty five and 27 percent of the isolates were found to be resistant to Mtz and Tet, respectively; the majority of these resistant isolates were from patients older than 21 years. Twenty percent of isolates were resistant to Cla; these were distributed evenly among different ages. Thirty two percent of the isolates were resistant to two or more of the antimicrobials. Conclusions: The high frequency of naturally occurring, antimicrobial-resistant strains of H pylori poses a national and world-wide problem for public health.