Mutant selection window of four quinolone antibiotics against clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis

Finally, The MIC value and the mutation status in the QRDR did not change after 14 passages in antibiotic-free medium. In conclusion, our findings suggest that the increased use of levofloxacin may contribute to the increased quinolone-resistance of S. pneumoniae and M. catarrhalis.