High secondary resistance to quinolones in German Helicobacter pylori clinical isolates

The aim of this study was to update data on levofloxacin/ciprofloxacin and triple resistance (resistance to metronidazole, clarithromycin and levofloxacin/ciprofloxacin) in Helicobacter pylori clinical isolates and to identify the impact of prior eradication therapies on their development.

We tested the antimicrobial susceptibility to amoxicillin, metronidazole, clarithromycin, levofloxacin/ciprofloxacin, tetracycline and rifampicin of 5296 clinical H. pylori strains isolated between 2006 and 2011. Information on prior eradication therapies was gathered and their impact on the development of antimicrobial resistance, in particular to levofloxacin/ciprofloxacin and triple resistance, was analysed.

From 2006 onwards, both levofloxacin/ciprofloxacin and triple resistance have steadily increased and peaked in 2011 with 29.1% and 18.6%, respectively. Unsuccessful prior eradication attempts proved a major risk factor for resistance development. Patients who had undergone unsuccessful eradication attempts harboured levofloxacin/ciprofloxacin- and triple-resistant isolates significantly more often than untreated individuals (26.7% and 18.1% versus 10.6% and 1.6%). Levofloxacin/ciprofloxacin and triple resistance occurred significantly more often in patients who had received quinolones when compared with patients who had not (44.5% versus 23.1% and 28.7% versus 15.6%). We did not observe any significant differences in resistance rates in the different German federal states.

Resistance to levofloxacin/ciprofloxacin and triple resistance have continuously risen and reached worrying numbers. Hence we strongly advise against the use of quinolones in empirical second-line therapies for H. pylori without prior susceptibility testing and/or a carefully taken patient medical history.