Minimal inhibitory concentration (MIC) values and different point mutations in the 23S rRNA gene for clarithromycin resistance in Helicobacter pylori.

摘要

Clarithromycin is recognised as the key antibiotic for Helicobac-ter pylori treatment, since it has the most powerful bactericidal effect in vitro compared to other available molecules. Unfortunately, primary clarithromycin resistance is increasing worldwide, and it is regarded as the main factor reducing the efficacy of eradication therapy. Clarithromycin resistance assessment is currently performed by agar dilution method or Epsilometer (E-test). Both these tools require bacterial culture, are time-consuming and show a low sensitivity, even in expert hands. To overcome these limitations, different polymerase chain reaction (PCR)-based approaches have been developed. These innovative methods have shown that three-point mutations (A2143G, A2142G, and A2142C) are responsible for more than 90% of clarithromycin resistance cases in Western countries. To date, only few studies yielding conflicting results have evaluated the relationship between minimal inhibitory concentration (MIC) values calculated by the E-test, and the presence of different point mutations detected at PCR [1-4]. In detail, two studies found an association between the A2143G point mutation and high MIC values, whilst two further studies found high MICs associated with the A2142G point mutation. On the other hand, we previously observed a lower H. pylori eradication rate in the presence of the A2143G point mutation as compared to either A2142G or A2142C, suggesting that such a mutation could be associated with higher MIC values [5]. On this basis, we aimed to further assess the MIC values associated with different point mutations.