Ceftazidime/avibactam alone or in combination with aztreonam against colistin-resistant and carbapenemase-producing Klebsiella pneumoniae

Abstract

MIC 90 values obtained for macrolides (erythromycin, azithromycin, clarithromycin) also ranged from 0.5 to 1.0 mg/L.Interestingly, decreasing susceptibility to azithromycin was observed within the ST1 isolates in comparison with non-ST1 isolates.All ST1 isolates showed MICs from 0.25 to 1 mg/L while 96% of non-ST1 isolates did not have MICs .0.25 mg/L.These data correlate with the previously recognized relationship between STs and azithromycin susceptibility of clinical Legionella isolates. 8It was found that rifampicin is the most active drug against isolates with an MIC 90 of 0.032 mg/L under in vitro conditions.In contrast, doxycycline was found to be the least active drug, with an MIC 90 of 2.0 mg/L.In summary, the in vitro activity of the tested antibiotics against the German clinical isolates was in agreement with results from other studies. [8][9][10] The introduction of routine susceptibility testing seems necessary for better understanding of the development of antibiotic resistance in vivo within the L. pneumophila population.The obtained MIC values can be used as a reference for defining ECOFFs and establishing the clinical breakpoints by EUCAST.