Preincubation of pneumococci with beta-lactams alone or combined with levofloxacin prevents quinolone-induced resistance without increasing intracellular levels of levofloxacin.
Preincubation of pneumococci with sub-MIC concentrations of ceftriaxone (1/16x MIC), cefotaxime (1/8x MIC), and meropenem (1/4x MIC) alone or combined with levofloxacin (1/8x MIC) over 6 h prevents the emergence of levofloxacin-resistant mutants after 96 h of incubation but does not affect the intracellular accumulation of levofloxacin in two penicillin-resistant pneumococcal strains, suggesting a link between the mechanism of action of beta-lactams and the emergence of quinolone-induced resistance in pneumococci.
Cottagnoud
Philippe
P
Department of Internal Medicine, Inselspital, Freiburgstrasse, 3010 Bern, Switzerland. pcottagn@insel.ch
Johnson
Maggie
M
Cottagnoud
Marianne
M
Piddock
Laura
L
D000890:Anti-Infective Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003470:Culture Media; D004347:Drug Interactions; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D064704:Levofloxacin; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation; D015242:Ofloxacin / Q000494:pharmacology*; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D047090:beta-Lactams / Q000494:pharmacology*
D000890:Anti-Infective Agents; D003470:Culture Media; D047090:beta-Lactams; D064704:Levofloxacin; D015242:Ofloxacin