Table 1.

Susceptibilities of S. pneumoniae ATCC 49619 (parent strain) and norfloxacin-selected mutants to fluoroquinolones and efflux pump substrates

CompoundRange of (median) MICs (μg/ml)
Parent strainPresumptive efflux mutants (n = 5)Non-efflux mutants (n = 18)
Norfloxacin416–32 (16)16–32 (16)
Norfloxacin + reserpine44–8 (4)16   
Ciprofloxacin0.52–4 (2)2–4 (2)
Sparfloxacin0.50.25–0.5 (0.5) 0.5 
Moxifloxacin0.120.12–0.25 (0.12) 0.12
Ethidium bromide416–32 (16) 4   
Acriflavine432 4