Clinical efficacy of triple therapy in Helicobacter pylori-associated duodenal ulcer

Standardization of disk diffusion test and its clinical significance for susceptibility testing of metronidazole against Helicobacter pylori

“…With the three interpretive categories used, the eradication rates for susceptible, intermediate, and resistant strains were 95.9, 62.5, and 52.6%, respectively. It has been observed that once treatment fails, emergence of metronidazole resistance in the organism is almost inevitable (3,27). In the present study, only 4.1% of susceptible strains were not eradicated while the rate of noneradication of intermediate strains was 37.5%; all of these became metronidazole resistant.…”

“…However, emergence of primary resistance and acquired resistance to these kind of drugs in H. pyloni may lead to treatment failure (3,7,10,11,21,27). Thus, evaluation of H. pylotn susceptibility to metronidazole before treatment appears to be important.…”

“…In other European countries, the resistance rate varied from 7 to 49% (8). The difference in the rates reported may reflect the variation in metronidazole usage between countries, since use of metronidazole alone can easily induce resistance to the drug in H. pyloni (11,14,24 A MIC of 8 ,ug/ml has been used in previous studies as a breakpoint to differentiate susceptible and resistant strains (11,13,18,27). In the present study, three interpretive categories were defined; strains with metronidazole MICs of less than 4 ,ug/ml were defined as susceptible, strains with metronidazole MICs between 4 and 8 ,ug/ml were defined as intermediate, and those with metronidazole MICs of greater than 8 ,ug/ml were deemed resistant, since strains with metronidazole MICs between 4 and 8 ,ug/ml can be more easily selected to become metronidazole resistant (24 Fig.…”

“…It is generally accepted that strains of H. pylorz with metronidazole MICs of more than 8 iLg/ml are resistant to metronidazole (11,13,18,27). However, there are no generally accepted criteria for the inhibitory zone size that differentiates susceptible and resistant strains in the disk diffusion test, although several studies have used this technique (4,7,9,12,13,(15)(16)(17)22).…”

Culture ofHelicobacter pylori under aerobic conditions on solid media

“…The MICs of metronidazole for 22 of the 23 isolates tested were measured under aerobic and microaerophilic conditions in duplicate using a conventional plate dilution method described previously (7,8).…”