An installation producing sterile bottles by blow molding starting from preforms (12), includes a sterilizing treatment unit (26), a thermal conditioning unit, a molding unit, where the sterilizing treatment unit (26) includes an atomizing device (36) provided with a nozzle (38) which sprays, onto each preform (12), in laminar-flow form, a stream (F) of vaporized sterilizing product at the interior of the preform (12) and along a mean axis of spraying (A2) of the nozzle (38), where this axis is generally parallel to the axis (A1) of the preform (12) during treatment and is radially off-center with regard to the axis (A1) of the preform (12).