Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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Indexed in KCI, KoreaMed, Synapse, DOAJ
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pISSN 2288-0585 eISSN 2288-6850

Evaluation of Frozen Antibiotics for Antimicrobial Susceptibility Testing of Helicobacter Pylori

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 1999 June Volume 2, Issue 1, pages 49-53.

Evaluation of Frozen Antibiotics for Antimicrobial Susceptibility Testing of Helicobacter Pylori

Lae Hee Chun, M.D., Jung Oak Kang, M.D., Sun-E Kim, M.D. and Ile Kyu Park, M.D.

Department of Clinical Pathology, College of Medicine, Hanyang University, Kuri, Korea


Background:Antimicrobial susceptibility testing of Helicobacter pylori(H. pylori) is not yet standardized but broth dilution or agar dilution are considered as standard methods. In the broth microdilution method, antibiotic dilutions of different concentrations are made each time, but most of it is discarded because only small volumes of dilutions are used. To improve this tedious procedure and the waste of reagents, antibiotic solutions in 96-well microplates were frozen at -20℃ to evaluate their useful storage periods.

Methods:Various concentrations of metronidazole(MTZ) and clarithromycin(CLR) solutions were divided into ten plates of 96-well microplates, sealed and stored at -20℃. The broth microdilution susceptibility test was done with fresh and preserved antibiotic dilutions each month on 5 occasions for 4 strains(initial minimum inhibitory concentration(MIC) for MTZ 1, 4, 16, 64 ug/mL, initial MIC for CLR <0.125, <0.125, <0.125, 32 ug/mL) of H. pylori. The difference of MIC values of more than ±2 log2 dilution was considered significant.

Results:For both MTZ and CLR, the difference of MIC values of fresh and frozen antibiotic solutions was within ±1 log2 dilution and the results of susceptibility test were the same for 7 months.

Conclusions:Various concentrations of frozen MTZ and CLR solutions could be used for at least 7 months for the antimicrobial susceptibility testing of H. pylori. (Korean J Clin Microbiol 1999;2:49~53)


H. pylori, Antimicrobial susceptibility test, Metronidazole, Clarithromycin, Preservation.