Comparison of Two Standardizations Used in Antibiotic Susceptibility Testing in Helicobacter pylori

Helicobacter pylori is a bacterium that is widespread in the world's population and constitutes a risk factor for the development of gastric cancer. One possible cause of treatment failure is antimicrobial resistance, indicating the importance of susceptibility testing.

Aims: The aim of this study was to compare the Helicobacter pylori susceptibility results obtained by two international standardization indicating the more reliable methodology to be used by laboratories.

Study Design: Transversal study.

Place and Duration of Study: Department of Gastroeterology, Hospital de Clínicas de Porto Alegre (Brazil), between January 2014 and July 2014.

Methodology: 50 isolates of Helicobacter pylori stored at -80°C were used in the execution of the susceptibility tests preconized by the British Society for Antimicrobial Chemotherapy (BSAC), British origin, and CDS Method of Australian origin.

Results: The minimum inhibitory concentration (MIC) values ​​for amoxicillin and clarithromycin in both standardizations were equivalents (κ=1.0000; p<0.001). However, the sensitivity of the British methodology was lowest (Sensitivity=85%). The Australian technique promoted more intense growth of H. pylori on the agar surface, allowing a more accurate reading of the inhibition zones of antibiotics (MIC).

Conclusion: Thus, CDS Method offered greater sensitivity and clarity in the interpretation of MIC in only three days of incubation.