Can aerospan cause bacterial infection if i have a spacer? also what diff between aerospan & dulera (formoterol and mometasone)?

No: If any infection it would fungal, to avoid that either with a spacer or without, drink water or gargle after adminstring the medicine, the difference between aerospan ( flunisolide); an inhaled corticosteroid (ICS) and dulera (formoterol and mometasone) (mometasone/formetrol) is that the latter is a combo medicine, containing an ICS and LABA ( Long Acting Beta Agonist)1;