T. Alarcon et al., Clarithromycin resistance stability in Helicobacter pylori: influence of the MIC and type of mutation in the 23S rRNA, J ANTIMICRO, 46(4), 2000, pp. 613-616
Thirty clarithromycin-resistant Helicobacter pylori strains (MIC range 8-64
mg/L) were subcultured in a drug-free medium and the MIC was determined ev
ery five passages to detect in vitro stability of resistance. Three out of
the 30 (10%) lost their resistance after 10, 13 or 18 subcultures (MIC decr
ease from 8 to 0.008, from 16 to 0.064 and from 32 to 0.016 mg/L). The effe
ct of four macrolides at subinhibitory concentrations on the development of
resistance was studied in H. pylori NCTC 11638 and TIGR 26695. A change in
the MIC was observed only when NCTC11638 was exposed to 0.5 x MIC of eryth
romycin for 20 days.