H. pylori Resistance to Antibiotics
from: Helicobacter pylori (Edited by: Lyudmila Boyanova). Caister Academic Press, U.K. (2011)
H. pylori resistance to antibiotics emerges most often from point mutations but also from efflux mechanisms, natural transformation, altered membrane permeability and, probably, β-lactamase. The resistance, especially that to clarithromycin and quinolones, often causes treatment failures. For this reason, if national or regional primary resistance rates are ≥15-20% for clarithromycin and ≥40% for metronidazole, the agents should be avoided for primary therapy of the infection unless susceptibility testing of the strains is carried out. Clarithromycin resistance-associated A2143G point mutation most often predicts eradication failures. Moreover, heteroresistance in H. pylori strains has been reported for metronidazole, clarithromycin, amoxicillin and quinolones. From <10% to >37% of the strains exhibit mixtures of genotypes. Importantly, both clarithromycin and quinolone resistance rates have grown sharply in many countries and multidrug resistance has been found in <5% in Europe and >14% in Brazil and South Korea. High primary resistance rates to clarithromycin (20->40%) and fluoroquinolones (20->33%) have been reported mostly in developed countries. Conversely, high primary resistance to metronidazole (≥76%), amoxicillin (6->30%) and tetracycline (≥15%) has been observed in some developing countries. Primary resistance and its evolution often depend on the country and national antibiotic consumption, patient characteristics such as age, sex, disease, prior antibiotic use and comorbidity, strain characteristics such as virulence as well as other factors. Post-treatment resistance rates have been usually much higher, often >3 times for clarithromycin and clarithromycin + metronidazole and ≥1.5 times for metronidazole and quinolones, compared with those of the primary resistance. In brief, a worrying evolution of antibiotic resistance in H. pylori and disturbing multidrug resistance hamper more and more the success of the eradication of the infection. Knowledge on current H. pylori resistance patterns and evolution at global and local levels is highly important to show the efficacy or need for changes in treatment regimens and to improve the overall eradication success that also means the cure of the individual patient read more ...