Helicobacter pylori susceptibility to fosfomycin, rifampin, and 5 usual antibiotics for H. pylori eradication.

The aim of the study was to assess Helicobacter pylori resistance to fosfomycin, rifampin, and 5 other antibiotics. Susceptibility of 50 consecutive H. pylori strains was tested by E test and breakpoint susceptibility testing method. Overall and primary resistance rates were amoxicillin 2.0 and 0%, metronidazole 34.0 and 31.2%, tetracycline 2.0 and 2.1%, levofloxacin 18.0 and 16.7%, rifampin 12.0 and 10.4%, and fosfomycin 8.3 and 6.5%, respectively. Clarithromycin resistance was >20.0% in all patients (22.0%) and in untreated subjects (20.8%). Rifampin resistance was higher than those usually reported. Quinolone resistance rose from 2005-2007 (8.7%) to 2012-2013 (18.0%). High double/multidrug resistance rates (overall 22.0% and 20.0% in untreated adults), including a 5-fold resistance, were found. In conclusion, fosfomycin and rifampin resistance rates were much lower than that of metronidazole and slightly lower than those of clarithromycin and levofloxacin. MICs90 of both fosfomycin and rifampin were lower than those of clarithromycin and metronidazole. Thus, in countries of high/increasing H. pylori resistance and multidrug resistance, both rifamycins and fosfomycin could be helpful in rescue regimens.

Two-decade trends in primary Helicobacter pylori resistance to antibiotics in Bulgaria.

Evaluating long-term trends in antibiotic resistance can predict earlier the short-term changes in resistance patterns. The aim of the present study was to compare primary resistance rates in 501 Helicobacter pylori strains in 2007 to 2009 to those in 1990 to 1995 (179 strains) and the antibiotic MICs to detect the 20-year resistance evolution. In 2007 to 2009, strains from children exhibited lower resistance rates to metronidazole (16.4%) and ciprofloxacin (2.7%) than those from adults (27.3% and 10.3%, respectively). In 2008 to 2009, more children (29.3%) harbored clarithromycin-resistant strains compared to the adults (17.4%). Overall clarithromycin resistance rate (19.4%) in 2007 to 2009 was much higher than that in 1990 to 1995 (6.2%). MIC(90) of erythromycin in 1990 to 1995 was 142.2-fold lower than that of clarithromycin in 2007 to 2009. Clarithromycin MIC(90) increased >42-fold since 2001 to 2004. Quinolone resistance rate increased 7.7-fold, being 9.2% in 2007 to 2009 versus 1.2% in 1990 to 1995, with a 5-fold increase in MIC(90). Conversely, the amoxicillin resistance decreased from 3.2% in 1996 to 1999 to 0.4% in 2007 to 2009. The MIC(90)'s of tetracycline remained stable but MIC(50)'s of both metronidazole and tetracycline before 1996 decreased about 4-fold to 2007 to 2009. In conclusion, associations between the resistance evolution and patients' age groups as well as the national outpatient antibiotic use have been found. H. pylori resistance to antibiotics showed many long-term changes, with a more rapid evolution for clarithromycin than for the other antibiotics. Metronidazole and tetracycline did not show a resistance evolution but exhibited a decrease in MIC(50) since 1990. The significant increase in ciprofloxacin resistance was found only by extending the study period to 20 years.