Emergence of a Helicobacter pylori isolate with reduced susceptibility to tetracycline in Germany

Abstract

antibiotic. All 50 isolates tested were susceptible to amoxicillin/ clavulanic acid (MIC90 6/3 mg/L; range 2.5/0.125–6/3 mg/L) and doxycycline (MIC90 1.5 mg/L; range 0.19–4 mg/L). For co-trimoxazole (MIC90 4/76 mg/L; range 0.047/0.893–6/114 mg/L), 78% of the isolates were susceptible, 16% were intermediate and 6% were resistant. Overall, 70% of the isolates were susceptible to ciprofloxacin (MIC90 2 mg/L; range 0.064–2 mg/L). Doxycycline and amoxicillin/clavulanic acid have been shown to be effective when used alone for the treatment of localized melioidosis or as maintenance therapy following septicaemic melioidosis. The rate of resistance to co-trimoxazole in the present study is lower than that described in Thailand (13%), while Ho et al. reported lower susceptibility (8.5% of 71 isolates) to ciprofloxacin compared with our findings. The use of fluoroquinolones for treating melioidosis has generally been controversial because of high in vitro MICs for some strains of B. pseudomallei, which exceed levels that can be achieved in serum. However ciprofloxacin is still used in the treatment of melioidosis because it has bactericidal activity, a prolonged postantibiotic effect and has good penetration into phagocytic cells, which might eliminate or inhibit the production of glycocalyx. Our in vitro studies indicate that of the four antibiotics tested doxycycline and amoxicillin/clavulanic acid are the preferred oral prophylaxis to be considered or further explored in our local context.