Comparison of Two Standardizations Used in Antibiotic Susceptibility Testing in Helicobacter pylori
Simone Ulrich Picoli *
Universidade Feevale, Institute of Health Sciences, ERS 239, Number 2755, Novo Hamburgo, Rio Grande do Sul, CEP 93525-075, Brazil
Bruna Rafaella Becker
Universidade Feevale, Institute of Health Sciences, ERS 239, Number 2755, Novo Hamburgo, Rio Grande do Sul, CEP 93525-075, Brazil
Luiz Edmundo Mazzoleni
Universidade Federal do Rio Grande do Sul, School of Medicine, Porto Alegre, RS, Brazil
Erli Neuhauss
Centro Universitário UDF, Brasília, Distrito Federal, Brazil
João Carlos Prolla
Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Gastroenterologia e Hepatologia, Porto Alegre, RS, Brazil
*Author to whom correspondence should be addressed.
Abstract
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.
Keywords: Helicobacter pylori, microbial sensitivity tests, reference standards, minimum inhibitory concentration, amoxicillin, clarithromycin