Hypermutability in clinical isolates of is uncommon and is unrelated to ciprofloxacin resistance

S. Aathithan (1) , G.L. French (1)

1 Division of Immunology

We investigated hypermutability in and its association with ciprofloxacin resistance and mutations in the quinolone resistance-determining region (QRDR). Sixty-four strains of isolated in London, UK, between 1995 and 2002 with widely differing ciprofloxacin minimum inhibitory concentrations (MICs) and known and sequences were tested for mutation frequencies by selection with rifampicin. Only three hypermutable (frequency ≥10) strains were identified, with ciprofloxacin MICs of 0.25, 8 and 64μg/mL. There was no relationship between hypermutation and the ciprofloxacin MIC or QRDR mutations. Screening selected strains with streptomycin did not reveal any hypermutators, and screening with ciprofloxacin identified only two of the three hypermutators identified by rifampicin. Hypermutation in is uncommon and does not contribute to accumulation of QRDR mutations or directly to ciprofloxacin resistance.

Mots clés: Enterobacteriaceae; Random hypermutation; Fluoroquinolone resistance

S. Aathithan, G.L. French. Hypermutability in clinical isolates of is uncommon and is unrelated to ciprofloxacin resistance. International Journal of Antimicrobial Agents, 2010, 36 (3), pp.239. ⟨10.1016/j.ijantimicag.2010.04.010⟩. ⟨hal-00608988⟩